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POLTIPS-3 User Guide - National Oceanography Centre

1. 15 Why do some days only Nave three 4442252 16 Why is the phase of the moon shown on atide tabl amp sill si 16 Equal Interval Pred tions cc cccccccecccenceeeeeeescneneeeeeeescaeeeeeeeeesscaeeeeeeeesscneeeeeeeeeeeeessaenaeeeeess Locations with unusual tidal characteristics Formetting the List ViGW cceccccceceecceneeeeeeeesceaneeeeeeescaaeeeeeeeeaeeessaeseeeeeessceeseeeeeeessenneeeeeess Saving tidal data to disk or the 1 6 ae TIS COS Cie Y SULL LTL Wising the Clipboard zo n a n n m Thi el Ste SH CS Aa LA AYA AYALARA L ernie Graphs Of the tide a a D Al Formatting the graph view EN Switching between the different A PAEA Selerting a port for Showing the location of a port on the 28 Page2 Saving your tide table StH 35 Using your OWN harmonic 4 165 37 About Harmonic Constants Deta
2. ns Wizard Ste E 21x The Text Wizard has determined that your data is Fixed Width If this is correct choose Next or choose the Data Type that best describes your data iginal data type Choose the file type that best describes your data C Delimited Characters such as commas or tabs separate each field Fixed width Fields are aligned in columns with spaces between each field Preview of selected data 1 ALBERT BRIDGE 2103 08 2001 01 39 3103 08 2001 08 36 0 39 4103 08 2001 13 56 5 73 5 6 7 Units METRES TZ GMT only Datum Chart Di 5 70 03 08 2001 21 11 0 29 E Ej Einish 4 Excel will suggest some columns by putting the date and timein one and the heightsin a second one Accept these by dicking next ns Wizard Step 2 of 3 2x This screen lets you set field widths column breaks Lines with arrows signify a column break To CREATE a break line click at the desired position To DELETE a break line double click on the line To MOVE a break line click and drag it ata preview m p m ALBERT BRIDGE TZ MT only Units METRES Chart Dat 03 08 2001 01 39 5 70 03 08 2001 08 36 0 39 0370872001 13 56 5 73 0370872001 21 11 0 29 Cancel lt Back Finish Page 41 5 Clidk finish to accept the default settings for each column 6 You will probably need to widen column A
3. Page50 Frequently Asked Questions aboutT ides The Applications Group at the Proudman Oceanographic Laboratory are often contacted by people vventing to know about tides For this we compiled a Frequently Asked Questions page for the POL web site Thisis included bdow 1 What is a tide Thisis not as obvious as it may sound it is not just the rise and fall of the water in our s s and oceans tides are only one of the contributing factors in this rise and fall A tideis the regular and predictable movement of water caused by astronomical phenomena the way the earth moon and sun movein rdation to each other and the forceof gravity These are the values that you can seein tide tables Movement of water caused by meteorolog cal effects for example winds and atmospheric pressure changes are called surges These are not easily predictable and require powerful computers and sophisticated software to predict just 36 hoursin advance These are the reasons why tide table predictions do not always agree with observations POL develops storm surge modds for flood forecasting that have been run at the Met Office since 1978 A large positive storm surge can add afew metres to the predicted weter level There is also wave movement which is purdy wind generated and impossible to predict accurately Therefore statistical values are used such as sigificant weve height which is the average of the hiqnest one third of Waves 2
4. Mean Low Water Springs MLWS average level of low water during periods of spring tides Mixed Tide tides that are neither totally semidiurnal or diurnal however one or the other is usually predominant Nenp Tides tides that usually occur around the time of the first and last quarters of the moon and have a smaller than average tidal range Semidiurnd Tides tides that have two hich waters and two low waters every 24 hours 50 minutes N rly all the tides around the UK re of this type Page58 Shdlow Water Influence a value that indicetes how much shallow water effects influence the overall tide Seetable belovv Value Desciption less than 0 1 small influence tide should havea typically nusoidal profile 0 1 to 0 2 moderate influence tide may show dightly unusual feetures particularly during neap tides 0 2 to 0 3 si mificant influence tide is complex and wil probably have more than 4 tides per day see the section on locetions with unusual tides on page 17 greeter than 0 3 very significant influence tide will have a very unusual profile possibly switching between semidiurnal and diurna tides Will certainly show more than 4 tides per day see page 17 Spring Tides tides that usually occur one or two days after new and full moon and have a larger than average tidal ranges Surges the moverrent of weter caused by meteorological effect eg Wind atmospheric pressure changss The
5. The diagrams bel ovv show atypical tidal curve for three places round the UK co t Lowestoft Portland TTT II m I I II In some parts of the world there is only one high and one low water each day diurnal for example in Karumba Australia In other places it veri es between semi diurnal and diurnal as in Musayid in the Arabian Gulf 8 What are spring tides and neap tides When the eerth moon and sun arein line during new and full moon the bulgss of water caused by the moon and sun occur in the same place on the eerth s surface The lunar tideand the solar tide are reinforcing each other which leads to higher than average high tides and lower than average low tides These are called spring tides When the earth moon and sun form aright ange at 90 the high water caused by the lunar tide coinddes with the low water of the solar tide This produces lower than average high waters and higher than average low waters which are celled neap tides They occur approxi medy 7 days after spring tides 9 W hy are they called spring and neap tides means low that 15 an essyone Spring tides be confusing because they have nothing to do with the season It is not exactly known Where the word spring comes from in this context but there are two possible origins One possible
6. Thisis possibly the most common question staff at the laboratory are asked and it could be somethingto do with the fact that many reference books explain it incorrectly Most people think the moon rotates round the earth In reality the earth and the moon rotate about a common centre just inside the earth s surface indiceted by the light blue dot on the diagram At this position the two forces acting gravity towards the moon and a rotational force away from the moon are perfectly in balance They have to be otherwise the earth and moon would not stay in this orbit indicates centre of rotation the Earih Moon system The rotational force Gravity is sironger s stronger than than the rotational gravity force The tidegenerating force is the difference between these two forces not just gravity as most people think On the surface of the earth nearest the moon gravity is gete than the rotational force and so there is a net force towards the moon causing a bulge towards the moon On the opposite side of the earth gravity is les as it is further from the moon so the rotational force is dominant Hence there is a net force away fromthe moon It isthis that creates the second bulge away from the moon Page52 5 W hy are the tides not the same all round the coast of Britain You might expect that as Britain passes under the bulge of water time of high water would be roughly the same for all points on the coast but it isn t
7. noted that for twicedaily tides the maximum tidal rangss occur just after the full and new moon and how in March and September they were likely to be even larger still Strabo c54 BC to AD 24 also noticed that thetidal rangein the Perdan Gulf wes greetest when the moon is furthest from the plane of the equator and are small and irregular when the moon passes through the equatorial plane Of course not all facts about the tide were scientifically correct Aristotle is edited with the lavvth t no animal die unless the tide is going out This legend persisted for along time and even as recently as 1595 Parish Regstersin Hartlepool recorded the phase of the tide along with the date and time of each death By the mid 17 century many theories were being proposed to explain the movements of the tide Galileo 1564 1642 stated that tides were caused by the motion of the Earth around the Sun and its own rotation on its axis inducing motionsin the sa which were modified by the shape of the seabed This is to what actually happens than Descartes 1596 1650 theory that space is filled with an invisible matter celled Ether which is compressed as the moon passed overhead and pushes down on theoceans However Kepler 1571 1630 wes the first to state that the Moon exerted a gravitational attraction on the weter In the years that followed and as the laws of planetary motion and Qavitation became accepted Kepler s idea of the tid
8. Lord Kelvin and George Darvin around 1910 however the most complete algebraic expansions were completed by Dr Arthur Doodson left in 1921 then secretary of the Liverpool Tidal Institute and from 1946 to 1960 Director at Bidston In 1924 the Liverpool Tidal Institute under the directorship of Professor Proudman at Liverpool University relocated to Bidston Observatory and the first tide predicting machine wes installed This machine could be programmed with the harmonic constants for any location and used to predict the tides for any date and time A yearlytide table took nearly a week to produce Five years later the Liverpool O bservetory of the Mersey Docks and Harbour Board and the Tidal I nstitute of the U niversity of Liverpool amal gamated becoming the Liverpool Observatory and Tidal Institute Dr Doodson now associate director continued his ground breaking research into new methods for the analysis of tides Two tidepredicting machines were now in use the only two in the British Empire and the tidal expertise of the institute received worldwide acdaim During the Second World War valuable work wes carried out at the observatory The staff worked seven days a week from early morning to late at nicht analysing and predicting tides towards the wer effort Tidal predictions were swiftly predicted for the seas around Burma France and Holland During these years one of the tide predicting machines wes placed in ase
9. The problem is caused by the land that getsin the wey of the moving weter As the earth rotates the weter has to move to generate the high tides but because of the shape of coastlines and the variation in sea depth bathymetry there is alag Every location has a unique coastline and bathymetry that gives each location its unique tidal pattern 6 How often do high tides occur In UK waters approxi metely every 12 hours 25 minutes You may wonder why it is not exactly 12 hours but you must remember that the moon is also orbiting around the eerth By thetime a point on the earth s surface has rotated from point x to point y 12 hours the moon has also moved a small amount so the earth hasto rotate for an extra 25 minutes from point y to point zto be under the high water bulge 7 Are there alvvays tuvo high tides a day No Although most places in Britain experience approxi metely two tides a day semi diurnal there are some places which experience what is known as adoublehiqh water eg Southampton or doublelow water eg Portland This is caused by the shape of the coastline and the bathymetry sea depth Even for vvell behaveci locations when you look at a tidetable you will see that some days only have 3 tides Thisis because the average time between high weter and low weter is 6 hours 12 minutes and not exactly 6 hours Therefore on certain days the fourth tide actually gets pushed across into the next day Page53
10. points but in its own units to allow greeter precision in specifying the size To convert from point size into POLTI PS 3 font size multiply by approxi metely 12 Point Size POLTIPS 3 Size Point Size POLTIPS 3 Size 20 pt 240 11 pt 132 16 pt 192 10 pt 120 14 pt 168 9 pt 108 12 pt 144 8 pt 96 The predsesralingis 12 085 but multiplyingby 12 5 for all paint sizes bdow 24 Appearance tab This tab allows you to adjust some of the more common properties that affect the appearance of the tide table High and Low Water Custom Tide Table Format k xi Font Appearance Advanced Tides Show IV High Waters IV Low Waters Months per page Days of the week IT Moons phases Columns per month IV Port location latlong Time and height units Title Lines FREE si De C3 64 C3 C4 r Relative positioning offset Date H ps Date V 4 Time jo y Height F C None C Dash r Column Lines Single C Double C None C Dash r Footer Lines C None Cancel C Single Double C Single C Dash Double Page32 Tidees llovvs you to select whether you went just high waters just low waters or both of them default You can also turn both of them off although this would not leave much in the way of data Show Q ves you the option of displaying the days of the week the location of
11. 02 05 11 Aberdovey 5232 N 04 03 W41 Aberporth 52 08 N 04 33 W 4 2 In the above example Aberdaron will be plotted on the map at 52 48 North 4 43 West The first number after the position indices at what zoom level the port should be displayed 1 always displayed 2 3 4 means that it is only displayed as you zoomin further The last number on the line indicates where the text is written rdative to the location marker see the example bdow Thisis used to prevent the names of ports in dose proximity overlapping Uses position 3 Positi Position 3 ition 2 osition osition Ri Position 5 6 Position 1 Uses position 5 o Uses position 1 Position 6 Position 8 a Bosition T Uses position 7 To beableto dick on a port and have it automatically selected in the input dialog box the port name in the lationgb file and the index dak file must be the same although it is not case sensiti ve Page40 Using the data in Microsoft Excel 97 If you paste the data into Microsoft Excel all the information will be placed in thefirst column of the spreadsheet To make the data more useable you really need the date and time in one column and the leveisin another column To do this follow these steps 1 5862 column A bydickingon the letter amp the top of the colum 2 Fromthe Data menu select Ted to Columns Step 1 of 3 of thetext to columns wizard appears 3 Sadet Fixed Width for the original data type and dick the next button
12. a period of 12 hours 25 minutes The second exampleindudes M2 and S2 the prindpal lunar and solar constituents and a prediction made with this will how asimple gpringneap variation Thefinal example is of areal port not disdosed as it is for sample purposes only and uss old data and contains 17 harmonic constants Accessing the sample ports included with POLTIPS 3 If you have a UserData licence the entries for these three sample ports will already be set up in the NDEX DAT file If you havea customised POLTIPS 3 licence these ports are not listed in the INDEX DAT file To access them you will need to place an entryin the index file for them to appear in the POLTIPS 3 input dialog box or copy the file INDEXUSR DAT over thelNDEX DAT file Licence Restrictions Users with a standard POLTIPS 3 licence cannot use this feature Users wth a customised version of POLTIPS 3 will be able to make predictions using their own constants for the same period as their licence Users with a U serData licence for POLTIPS 3 will usually have a 10 year licence this will have been specified when you purchased the softwere Showing your port on the map Page39 If you wish for your port to appear on the map you can insert an additional line per port into the file laklong bd which isin the POLTIPS 3 directory U se one of the existing linesin the file to line up the data as shown in the following example Aberdaron 52 48 N 04 43 W 41 Aberdeen 57 09 N
13. bdow When you make any changss to the settings dick dther the Apply button to see the effect of the changss without dosing the dialog box or the OK button to accept the changes and dose the dialog box Once you have dicked Apply you can no longer select cancel you will need to change the settings back manually Font tab High and Low Water Custom Tide Table Format E x Font Appearance Advanced r Font Selection Typeface Name Size Bold Italic Title Arial izl ps Subtle fa m 7 Month fail vil lin ARS Date Arial Narrow zl 15 F da Data Arial Narrow 2 H Footer fail mpo T C Page31 This tab allows you to select the font size weight and italic properties for each of the 6 parts of the tidetable All the fonts installed on your sytem should be listed in the drop down list under typeface name Titlerefers to the top line of thetide table used for the port name Subtitle is the line directly belovv the title used to display the time zone latitude longtude and the year Month is the font settings for the month headings Date is the settings for the date value Datarefers to the font used for the main tidal data as wal as the time and units headings and the day of the week Footer is used for the datum statement and the footer text that appears at the bottom of the tide table In POLTIPS 3 thefont size is not specified in the conventional unit of
14. label Predictions to Chart Datum Y Axis scaling Plot style Automatic C Markers C User defined Lines 1 2 to m C Markers lines axis scaling Marker size Automatic Large Weekly C Small Cancel C Daily C Six hourly Grid lines C Hourly W Grey background If the X axis timeaxis scalingis set to automatic then POLTIPS 3 will select the appropriate one based on the period of time displayed on the screen When vieving a high and low water prediction it is advisable only to use markes for the plot style as using lines simply joins the points together rather than showing the actual hape of the tide You must use an equal interval prediction to get a sensble plot of the tide between the turning points Switching between the different views You can switch between list view tide table view and graph view by selecting the appropriate view from the output menu or by dickingon one of the three output buttons on the toolbar M Using the map POLTIPS 3 can display a map of the UK and the ports smply by seting Input Show Map or clidkingon the toolbar button When the map is first displayed only a selection of the ports availablein POLTIPS 3 are hown However you can zoom in to a male area of the coast using either the zoom buttons on the toolbar alal or using the left mouse button to drag a rectand e over the area of the map you are interested in Page26 alo Edt View Inp
15. of Venus to earth is still more than 100 times further away than the moon Hence the tidal force is approxi mately 0 000054 times that of the moon That equates to a movement in sen level of less that a quarter of a millimetre one hundredth of an inch The next most sqnificant planet isJupiter where the tidal force is 10 times less again So as you can see the effect of the planets on the tide can safely be ignored Even if all the planets line up such that their effects are combined the additional force would be minuscule During 3rd May 2000 Mercury Venus Mars Jupiter and Saturn lined up with the sun and moon At the time a rumour circulated that the collective gavitational pull would initiate earthquakes tidal waves and volcanic eruptions something which of course never happened 14 How can tide tables be produced so accurately There are many different steps involved in obtaining the final numbers that go into atidetable Beforeatidal prediction can be made for a port a long sequence of tidal observetions for that port are neaded called atime series This time series will indude all the astronomical effects and local coastline depth effects which make up thetide as well as the weather induced effects called the surge see question 1 Asshown in questions 6 and 8 there are certain frequencies that are known to occur in the tide Some of these are listed below Page55 e 12 hours 12 00 00 repeated pattern cyde due t
16. of the current date Hardware Requirements The minimum requirements for POLTIPS 3 isa PC running Windows 95 98 NT4 ME or 2000 not Windows 3 1x with about 5MB of free hard disk space The recommended minimum is 200M Hz Pentium with 32MB or more of memory Page7 Prediction Methods Harmonic constants are useri for computing predictions for standard ports with time and height differences used for the secondary ports Some standard ports have additional tida terms called Shallow Water Corrections Harmonic Constants and Standard Ports A set of harmonic constants exists for most of the main ports around the coast These are celled standard ports and POLTIPS 3 can compute equal interval predictions as vvell as high and low weters Sets of harmonic constants usually exist only for locations where there has been a tide gauge and a suitable period of observed data to analyse for example ports on the National Tide Gauge Network or locations of particular scientific interest A few standard ports have quite a complex tidal pattern that cannot be accuratdy reproduced just using harmonic constants These ports have additional factors called shallow water corrections used to make small adjustments to the high and low water times and haichts Equal interval predictions cannot be mede for ports with shallow water corrections Secondary Ports There are many locations around the coast where long periods of tidal observations do not exi
17. the port as a latitude and longitude the moons phases and the time and unitsof ha cht metres or fect on the tide table It is advisableto always have the units of height shown if you intend to publish the tide table If you turn this off you should ensure that it is displayed dsewhere on the page Months per page lets you select between 1 to 4 months per page of the tidetable If you want to use larger font sizes then you may want to select less than the default of 4 months per page 3 pages per year to allow space for the larger fonts Columns per month give you the choice of 1 to 4 columns per month The default and probably the most useful is 2 columns per page Relative positioningallows you to ENGLAND WEST finely adjust the positioning of the data MT Lat 5123 within its box The box isthe a allocated area on the tide table which 1 11 an v lge contains the 4 tides for a particular tu l wo te T date one date boxe is shown shaded in 2 ad n 17 026 47 o the illustration on theright Thesize 2 m s s me 05 ai of the box can very depending on the g os 131 4g ove 2a go is gx number of columns per month and the number of months per page therefore the rdative positioning values are specified as a percentage rather than an absolute measurement The Date H Timeand Height values are the horizontal positioning of the three values It specifies the position of the ri
18. the tide Combined with POL sinternationally renowned reputation for accuracy POLTIPS is one of the most powerful tidal prediction programs aveilable W hat s New in Version 3 e Improved user interface e Improved map display with simple scrolling and zooming e High water only or low water only predictions e Instant next 7 days this month or this year predictions e Improved standard tide table display Hourly height tide table format Custom tide table layouts to create your own unique look e Save predictions as text files to disk Copy unlimited size predictions to the dipboard Use POLTIPS with your own harmonic constants customised and U sData licence only o Tidal statistics for locations Formatting for the standard list output e Select metres or feet as your preferred unit e Select accuracy of 1 2 or 3 decimal places e Latest data sets for the most accurate predictions Page6 VV hat are the differences betvveen the Standard Customised and UserData versions of POLTIPS Due to the different requirements of the wide veriety of POLTIPS users we have created three different versions of POLTIPS 3 They are basically the same program but have certain restrictions imposed The standard version can be bought with athe a three or five year licence and contains around 700 UK ports This has asligntiy reduced accuracy over both the POL in house predictions and the Customised version of POLTIPS 3 Usersof the sta
19. to see the data as the date and time will not fit within the default column width A B G D E 01 01 2002 02 49 01 01 2002 08 20 01 01 2002 15 13 01 01 2002 20 48 02 01 2002 03 33 02 01 2002 09 05 02 01 2002 15 57 02 01 2002 21 33 03 01 2002 04 15 111 03 01 2002 09 50 12 03 01 2002 16 38 13 03 01 2002 22 18 14 04 01 2002 04 54 is 04 01 2002 10 37 16 04 01 2002 17 18 1 11 3 44 19 3 23 16 3 44 1 25 3 11 31 AVONMOUTH TZ GMT only Units METRES Datum Chart Datum 7 Once you have the data in this form you will be able to use many of the excel functions to derive additional statistics and informetion about the tide produce frequency distributions or use the chart wizard to produce graphs 16 14 v t bag AVS RESETS TEN 12 tter oot tee 0 0 00 K 10 5 2 8 Series1 6 g 2 996969 0 T T T T 30 12 2001 04 01 2002 09 01 2002 14 01 2002 19 01 2002 24 01 2002 29 01 2002 03 02 2002 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Page42 Time andTide Tides are the alternating rise and fall of the surface of the sess and oceans They are due mainly to the gauitational attraction pull of the moon and sun on the rotating earth Two hich and two low tides occur daily around Britain and with average weather conditions scientists can predict their movements with condderable accura
20. type of prediction you can see how the tide changes over time Equal interval predictions are only available for standard ports not secondary ports s page 8 If you ak POLTIPS 3 to compute an equal interval for a secondary port you will be asked whether you would like to use the reference standard port or whether you would like to change to high and low waters for your sdected port Select the option you require to continue or cancd the prediction More information required x The location you have selected is a secondary port The only information POLTIPS has available for secondary ports are time and height difference of high and low water relative to a standard port usually a nearby location and one with similar tidal characteristics Please select one of these options to continue or click cancel Compute the high and low waters for the selected location C Compute the requested interval for the reference location Continue with selected option Cancel prediction The list view for equal interval predictions is the same as for high and low waters however the time intervals are equally paced The tide table view for equal interval predictions is completed y different from the high and low water tide table and is available only when the interval is set to 60 minutes this is often called an hourly height table Page 16 Note that all times for equal interval predictions are gven in GMT UT only Brit
21. use in POLTIPS 3 not the standard 1 000 ODN licence 2 000 odas 2 3 SAMPLE M2 AND S2 Each port has a minimum of 4 lines of 3 000 header information and then a list of the 1 000 ODN harmonic constants onepertine as 2 000 a0 shal shown in the example bdow 1 000 0 0 36 Page38 The first line has a singe value that indicates the number of harmonic constants for the port the second line hasthe port name which in the example is SAMPLE M2 ONLY The third line contains the datum shift to get from mean s level to chart datum sometimes called Z The fourth lineisthe height of Chart Datum rdative to Ordnance Datum and the name of the Ordnance Datum used eg ODN ODL ODB ODD As chart datum is normally belovv Ordnance Datum this value is usually negative Thisis followed by one line per harmonic constant i e if you specified there were 10 harmonic constants there should be 10 extra lines Each line has 3 values separated by one or more spaces The three values required for each harmonic constant are the amplitude in metres the phase lagin degrees and set for GMT UT and the harmonic constant number see table of harmonic constants on page 61 If you havea customised licence or aU serData licence then there will be a sample USERCON DAT file induded gving three examples the first two matching those shown above The first one contains just a inge M2 constant so any prediction made will look like a basc sine weve with
22. waters and the lowest low vveters Extreme Leas the term used to describe leves higher than HAT or lower than LAT caused by meteorolog ca conditions These can only be derived statistically and are usually quoted as the still water level that is likely to appear once every so many years Example of Extreme Levdsfor Dover Highest Astronomical Tide 7 23 10 yeer extreme level 7 74m 100 year extreme level 8 21m 1000 year extreme level 8 80m 10000 yeer extreme level 9 47m Extreme level information is available from POL for many coastal and offshore locetions Flood Tide the landward tidal flow from low water to high water The Flood timeisthe time between low weter and the following high weter GMT UT see Time Zones belovv Harmonic Constants the amplitude and phase of the various harmonic constituents that can be added together to calculate the overall tide See How can tide tables be produced so accuratdy in the Frequently Asked Questions section of this manual for more details Every location has a unique set of harmonic constants which are derived from tidal analysis of observations for that location Hamonic Constituents the tide is influenced by many factors and each one of these be represented mathematically by one or more simple sine weve functions Each one of these mathematical waves 15 Page57 called a harmonic constituent of thetide There are about 150 common har
23. 01 1200 11 94 1139 10 84 0640 3 29 M 1712 285 Tu 1826 2 33 Th 1803 2 95 F 1257 10 21 2306 10 67 4 1904 371 2 0523 3 11 17 0028 11 25 2 0000 10 56 17 0133 9 80 1129 10 57 0645 264 0619 3 18 0740 3 96 Tu 1751 3 18 VV 1253 11 22 F 1233 10 45 Sa 1412 970 3 2350 10 28 1912 2 92 1853 3 32 2028 4 18 3 0605 3 43 18 0126 10 64 0105 10 25 18 0300 9 72 1220 10 26 0739 3 20 0720 3 54 0929 399 W 1839 3 46 Th 1355 10 68 Sa 1355 10 32 Su 1542 9 85 2015 337 2014 3 54 2210 378 4 0047 10 05 19 0235 10 37 4 0236 10 39 19 0423 10 33 0700 3 69 0853 3 49 0904 3 54 1048 3 26 Th 1330 10 20 F 1508 10 51 Su 1523 10 77 M 1657 10 57 1946 3 59 2133 3 45 2158 3 07 2318 297 0205 10 17 0348 10 54 0358 11 14 0324 11 21 5 0819 371 20 1013 3 29 5 1038 279 20 1147 24 F 1449 10 59 Sa 1620 10 75 M 1638 11 60 Tu 1751 11 36 2116 3 29 2248 3 10 2317 2 25 6 0323 10 78 21 0453 11 06 6 0508 12 10 21 0013 2 26 0954 3 20 1120 2 80 1154 1 98 0612 11 94 Sa 1559 11 34 Su 1721 11 23 Tu 1745 12 48 W 1237 191 2236 2 58 2349 2 59 1835 11 94 0430 11 67 0547 11 66 0029 1 54 0101 182 7 1109 2 42 22 1215 231 7 0611 12 98 22 0652 12 40 Su 1702 12 17 M 1812 11 70 w 1305 33 Th 1323 6 In the illustration above the window has been resized to make the text deere Thetide table pagss is always sizeci to fill the width of the window however because the window is not usually the same shape as a piece of paper you will not be able to see dl the tide table amp once You can scroll up and
24. 2 12 08 39 15 53 12 07 44 17 01 12 06 32 18 04 13 08 38 15 55 13 07 42 17 04 13 06 29 18 06 14 08 37 15 57 14 07 39 17 06 14 06 27 18 09 15 08 36 15 59 15 07 37 17 08 15 06 24 18 11 16 08 35 16 01 15 07 34 17 10 16 06 21 18 13 17 08 33 16 03 17 07 32 17 13 17 06 19 18 15 18 08 32 16 05 18 07 30 17 15 16 06 16 18 17 21 16 07 10 7 27 17 17 ne 412 90 Nm 2 Note that all times for sunrise and sunset are hown in GMT only Page29 Page30 Custom tide table format One of the new features to POLTIPS 3 usually available only on the customised and U serData licence is the ability to customise your own high and low water tide table layout To access this make a high and low water prediction as normal and then select Output Custom Tide Table HLW The default layout for custom tide tables looks like the picture bel ovv ani M BOT ven moe opt Mic Saj simimipi lella 2 ENGLAND WEST COAST AVONMOUTH GMT Lat 51 30 N Long 2243 W Year 2002 January February March Apri i al 1 16 1 1 tS 16 2 4117 a 7s 2 vl k 25 17 4 3 16 3 18 ag age nl wom 2 u p 19 4 q L x 4 19 i 5 20 615 5 20 55 120 4 5 20 a E 51 neat hs To changethis layout select Output Format Tide Tableto bring up the dialog box shown below As there are many settings that can be changed they have been slit across three tabs called Font Appearance Advanced shown
25. Files cs Pista Da T Accessing the sample ports ind uded with 1 5 39 39 Show ng your port on the aa a aa E aAa E KA AEE TE EEEE EEA EETA 39 Usingthe data in Microsoft Excel 97 41 Time and Mes asasan a Aaaa ad Aya 43 4 If gravity is aways pulling towards the moon what causes the bulge on the opposite side of the 52 5 Why are the tides not the same all round the coast of Britain 53 6 How often do high tides seere 7 Arethere aways two high tides a day 8 What are spring tides and neap tides 14 How can tide tables be produced so 55 15 Whee can I find out more information about tides 56 E eces ATU PA EA A EE AA AA TA A A A A AA Ta TATA 57 Page3 Warranty and Liability 1 If the licence disk or CD ROM is defective POL will replace it at no charge provided the defective item is returned within thirty 30 days from the date of despatch from POL 2 POL will refund the purchasing price provided al
26. HWS see dossary Mean High Water Neps MHVVN see dossary Mean Low Water Neps MLWN see dossary Mean Low Water Springs MLWS sce dossary TideType dives the value which indicates whether the tide is semidiurnal diurnal or mixed see dossary Shdlow Waer Influence like thetide type this is a value that indicates how much shallow water effects influence the overall tide Values greeter than 0 2 indicates a port that shows unusual tidal characteristics especially during neap tides see dossery Statistics for the Selected Period Highest Tidein period the hiqnet level thetide reaches in the sdeded time period Lowest Tidein period the lowest level the tide reaches in the selecteci time period Largest Tidal Rangein period the biggest difference that occurs between a high water and an adjacent low water in the sdected time period Average Flood time the average time taken for the tide to come in i e average time between alow water and its adjacent high water Average Ebb time the average time taken for the tide to go out i e average time between a high water and its adjacent low water Quickest Flood time the fastest time that thetide comesin in the selected time period Page23 Graphs of the tide In addition to the list view and thetidetable view POLTIPS 3 can display the tide as a gaph How this graph looks depends on whether you display ahigh and low water prediction or an equal interv
27. How far ahead can the tide be predicted Since the tide is caused by the astronomy of the earth moon sun system which is known very accuratd y and can be predicted well into the future the tides also be predicted wal into the future So if you want to plan your sailing dub events for the year 2005 get in touch and for a mall fee the Applications Group will provide you wth the tide table When trying to predict well into the future we have to take into account the rise in goba sea level The further into the future we try and predict the more significant this effect can become Page51 3 W hat causes tides Tides are caused by the effects of gravity in the rth moon sun system and the movement of those three bodies within the system If you imagne that the earth is completely covered in water there are two bulges of water one towards the moon and another on the opposite side see question 4 The rise and fall in sa level is caused by the earth rotating on its axis underneath these bulges of water There are two tides a day because it passes under two bulges for each rotation 24 hours see question 7 This is called thelunar tide Two bulges of water are also caused by the sun called the solar tide and these can either reinforce or partially cancd out the lunar tide to give spring and neap tides see question 8 4 If gravity is always pulling towards the moon what causes the bulge on the opposite side of the earth
28. POLTIPS 3 User Gulde Proudman Oceanogaphic Laboratory Biciston Obsenvetary Bidston Prenton Merseyside CH43 7RA t 151 653 8633 f 0151 653 8345 apdictimsapd acuk Pagel Contents Warranty and Liability ranei tein eine SAR 4 Introdudion The Applications Group POLTIPS 3 tidal predictions software VVhieEs N MVinVersi ona ih Sakic SER ran DISSE RS L r SS 6 What are the differences between the Standard Customised and U serData versions of POLTIPS Publishingtidal prediction on the Internet 6 7 Praid n M Ahs aaia roar raa 00 es 8 Conventions used in this menual 222ss seere EEN 8 Installing and starting POET IPS o cceeeccececeeeeeeceeeeeeeeeeecceeeeeeeeesceaeeeeeeeescceeseeeeeesseeseeeeeeneees 9 Howto install POLTIPS 3 Please read before i Stall 9 Manual installation Of MOONS phases 9 Howto start POLTIPS 34 nit AET Ports with complex tidal patterns ad THE POETIPS 3 WIMGOW Setting the parameters for the 1 8 13
29. This kind of geographical effect is very important and because of it you should use local tide tables available from tackle shops when possible Cromer Lowestoft and Aldeburgh are fairly dose to each other on the Eat Andian coast However high tide is hours apart at these places This is predsey the opposite to Southend and Herne Bay which face each Page44 other across the mouth of the Thames Their tides differ by only afew minutes Without detailed geographical information it is impossible to predict these differences so tay with local tide tables Geography also affects the tidal range Looking at tide tables for all of Britain its dear that the height of the tide varies around the country For example the spring tidal range at Avonmouth is 12 2m 40ft while at Lowestoft it s only 1 9m 6ft Weather which can havea profound effect on the tide isimpossble to predict when calculating tide tables Strong Winds and abnormal atmospheric pressure are two of the main causes of altered tides For example astrong wind blowingon to land has the effect of piling up the water Gvinga higher than predicted tide Page45 Page46 A History ofTidal Prediction It has long been known that there is arelationship between the movement of water in our sess and oceans and the position of the sun and moon Pytheas of Marseilles in the 5 Century BC wes the first credited with linking the tides to the position of the moon Plinythe Elder AD 23 79
30. a tides removed and compare them to a prediction with all thetides Alternatively compare the turning points to a gaph of a prediction mede amp a 10 minute interval for the same period 18 Output precision and units Datums The output precision on the list view and the tide table view can be set to 1 2 or 3 places the default being 2 Note that although the data can be output to 3 decimal places it does not imply that the data is accurate to 3 decimal places as there are many factors that can influence the tides see Time and Tide on page 41 To change the precision of the output select Output Precision You also have the option of switching the units used for the sea leva between metres default or feet Select Output Unitsand select the unit you require Note if you select feet for the units the value isa ded ma value and not fect and inches eg 4 5 means 477 4 6 and not 4 5 What is a Datum When messuring the hd ght of something you must specify what that height is measured rdativeto For example if you hold a ball out in front of you over a desk the height of the ball is say 70cm above the desk However if someone comes and takes the desk away you could say the height of the ball is 145am above the floor You have two different heights even though you have not moved your arm What has happened is that the datum has changed In the first case the datum wes the desk and in the secon
31. al prediction To bring up the graph of theti de select Output Graph or dick on the graph button on the toolbar The picture belovv shows how one month of high and low weters mignt look When you view the graph of a high and low water prediction blue diamonds indicate the time horizontal axis and height vertical axis of the In the picture bdow you can deerly see the springneap tidal ode New Preckcton POUTIPS v ini xi Fie Edt Vew Input Ouput Misc Hep B S sel alsmi llas 9 High and Low Waters for AVONMOUTH Time Zane GMT only Predictions to Chart Datum You zoomin to any section on the gaph by holding down the left mouse button and dragging from left to right across the graph You will see the area you are selecting change colour and when you rdeese the mouse button the sdected area will be scaled to fill the window You can also usethe buttons on the toolbar to zomin and out You can scroll left and right within the limits of the prediction usingthe left and right arrows on the keyboard or the toolbar If you view the gph of an equal interval prediction you get a continuous line showing the shape of the tide To get an accurate graph itis advisable to use an interval of 15 minutes or less for the prediction Bdow shows how a5 minute prediction for 2 days mignt look Page24 POLTF Fe Edt View Input Output Mec Help mi ARN lola
32. cret underground room in the Observetory grounds for security ressons Photographic facilities were obtained so that further copies of the predictions could be quickly provided in the event of their loss at sea Page48 In 1946 Dr Doodson took over as Director at Bidston and the Tide Prediction Service expanded It was hd ped by the construdion of alarge 42 constituent Doodson Lege predicting mechine in 1949 This mednine is still in working order at Bidston and can still predict thetideto an incredible accuracy The Doockon g machine wes the In 1961 shortly after the advanced tideprediction madine retirement of Dr Doodson the cf its day It uss up to 42 harrruric Liverpool Observatory and constituents to predict for any location Tidal Institute wes renamed The University of Liverpool Tidal Institute and Observatory In 1969 the Institute became a component body of the Natural Environment Research Council and wes renamed the Institute of Coastal Oceanography and Tides I COT It wes around this time that an ambitious marine research programme wes embarked upon with a Sqnificant increase in staff 1970 saw the installation of the institute s first mainframe computer an IBM 1130 This speeded up the computation of tide tables immensdy a yearly table now teking less than an hour to compute Thereduction of human intervention also meant that errors were less frequent so less time wes spent checking the results for t
33. ction takes you through what you need to know to produce your first printed tide table Setting the parameters for the prediction Before you can compute the tides you need to tell POLTIPS 3 where you would like the tide table for the duration of the tide table and the type of prediction Sdect Input Tidal Predictions to bring up the dialog box shown below Tidal Predictions s Port Name r Start date NO PORT SELECTED Bi zl El 4 End date P dr are 4 7 days This Month This Year ALLINGTON LOCK ALLOA Type of prediction AMBLE High and low waters AMLWCH x ANNAN WATERFOOT C Enuel interval H R ANSTRUTHER EASTER APPLECROSS C High waters only APPLEDORE C Low waters onl ARBROATH y ARDGLASS Statistics ARDNAVE POINT gt Cancel Show on map Adjust for British Summer Time BST First select the port you require from the list of ports You can ather scroll down thelist using the arrows and scroll bar or just start typing the name in the box and the list will scroll automatically to the right place Once you see the port name in thelist dick on it Now set the start and end date of the prediction you requirein the date boxes either by typingin the number directly or using the up and down arrows next to each box Alternatively just dick on one of the three preset buttons to meake a prediction for the next 7 days the current month or the current year The dates will be fi
34. cy Both moon and sun affect the tides but since the moon is much doser to the earth 240 000 miles instead of 93 000 000 miles it has more than twice the effect of the sun even though it is much smaller So to understand tides it is best to start with the moon and the lunar tide before looking at the effect of the sun As everyone knows the moon orbits around the earth However the earth isnot fixed rigdlyin space and asthe moon orbits it attracts the earth round in a monthly orbit of its own So the earth has a small orbit caused by the moon in addition to its annual one round the sun It isthe gavitational pull of the moon on the earth that keeps the earth in its monthly orbit Thisis just the same as when you whirl a weight round on a piece of string It is only by constantly pulling on the string that you prevent the object from flying off If you stop pulling completdy by letting go on the string the object does fly off Gravity acts in the same way as you pulling on the string and prevents the earth from flying off However unlike the string the attractive pull of gravity gets weaker as the distance between the objects increases and it becomes stronger of course the dose they get The earth is large so the pull of gravity on the side of the earth nearer the moon 15 tronger than the pull on the side of the earth farther from the moon The pull of the moon s gravity is just enough to keep the earth in its monthly orbit bu
35. d the datum wes the floor Likewise tide heignts must be measured to a specified datum the two most common being Chart Datum and Ordnance Datum athough some ports use a datum specific to that location for example a dock sll These are called special datums Chart Datum This isthe most common datum 4924 on tide tables and is defined as the datum of soundings on Admiralty Charts It is usually set to correspond to the lowest leva to which a tide can fall under normal conditions called the Lowest Astronomical Tide or LAT therefore making all the predicted tide level values positive However this is not always the case and for some ports the surveying authority has set chart datum above LAT Chart Datum does not conform to any uniform tidal level asit is based on the tidal range at the location Therefore it is not a suitable datum for comparing leas at more than one location Page19 Ordnance Datum Ordnance datum is sometimes referred to as land survey datum and isa horizontal plane It is used when the absolute heights along a stretch of Coastline nead to be compared The datum used for the British mainland and some of the dose offshore idands is called Ordnance Daum Newyn as it is based on the average value of mean sen level at New yn for the six year period from 1915 to 1921 to the subsequent risein mean sea level this datum is now about 0 2m below mean sea level at Newyn For locations not on the British mainla
36. down to see the rest of the page using the up and down arrows on the keyboard or the toolbar To move onto the next page of the tide table usethe left and arrows or page up and page down on the keyboard To print thetidetable select File Print or dick the print button on the toolbar Fromthe print dialog you can select which pags of the tide table you wish to print and the number of copies as well has being able to change all the settings specific to your printer Page 15 W hy do some days only have three tides The average ti me between successive turning points is 6 hours and 1272 minutes i e four tides take 24 hours and 50 minutes meaning the tide moves on by 50 minutes each day About every 7 or 87 day one of the tides moves across midnight into the next day leaving only three turning points on that day Why is the phase of the moon shown on a tide table The tide is directly rdated to the phase of the moon Springtides usually occur 1 to 2 days after new and full moon and neap tides 1 to 2 days after the first and third quarter The moon symbols are shown to enable easy identification of gorings and neaps A NewMoon B First Quarter C Full Moon D Third Quarter Equal Interval Predictions An equal interval prediction is one that gvesthe height of the tide at certain equally spaced time intervels for example every 15 minutes or every hour rather than at the specific time of high and low water Using this
37. e When the installation program asks for a destination folder to install POLTIPS into accept the default folder otherwise the automatic licence and font installation will not work POLTIPS 3 wil beinstaled on your computer s hard disk the default location is c Program Files POLTIPS 3 and an icon will be created automatically on the programs menu of your Start Button and on your desktop Manual installation of moons phases font The moon symbols font should install automatically provided you have installed POLTIPS into the default location and your Windows folder is ather c windowsor c winnt If the font did not install you can install it manually by copying the moonsymitif file from the floppy disk into the fonts folder inside your windows folder How to start POLTIPS 3 To start POLTIPS 3 dick on the start button select Programsand then Poltips3 Alternativdy doubledick the icon on your desktop Page9 Ports vvith complex tidal patterns Some ports have unusual tidal characteristics e g Bournemouth Cowes Poole Portland Southampton and Weymouth If you use POLTIPS 3 to do predictions for any of the above ports please read the saction Locations with unusual tidal characteristics on page 17 Page10 The POLTIPS 3VVindovv ol rediction POLTIPS 3 File Edit View Input Output Misc Help aia gt alm The picture above shows how the POLTIPS 3 should first look when you start the pro
38. e 51 entitled How can tide tables be produced so accurately If you have your own sets of harmonic constants for a location you can use POLTIPS 3 to compute tidal predictions based on these harmonics for any date and time within your licenced period These harmonics could have been obtained from either a tidal analysis carried out for you by POL derived from the POL Tida Analysis Software Kit TASK or from some other source To use this feature you must have either a POLTIPS 3 customised licence or a POLTIPS 3 UserData licence A UserData licence usually runs for 10 years Data Files To incorporate your own harmonic constants into POLTIPS 3 you must modify two files in the POLTI PS directory on your hard disk Unless you changed the default location when you installed POLTIPS this will be c Program Files POLTIPS 3 INDEX DAT If you have a customised licence this file will contain a list of the ports already induded in POLTIPS 3 however your licence will restrict access to most of them Thereisan example file called indeusr dat which can replace index dat that contains the additional three example ports induded with POLTIPS 3 Page37 If you have a U rData licence index d t will contain three sample ports only The indexfile contains one line per port and indudes the short port name three numbers a descriptive piece of text and the long port name optional The spacing of the information on the line i
39. e 87 2 MIN s Some harmonic constants have alternative names NE POL also NE POL also POL also nane known as narre known as nane known as 24 OQ MNK2 44 SOs MP3 104 MBz MSP2 30 OP2 MSK2 103 MAz MPS2 Page61
40. er Time BST for 7 months of the year which is GMT hour You can select BST byticking this box on the input dialog BST correction is only supported for high and low weter predictions and not for interval predictions Turing Points see hich and low waters Page60O Table of Harmonic Constants No Narre No Narre No Narre No Narre 1 Sa 30 2 59 2506 3IVINe 2 Ssa 31 Mb 60 MSKe s Me 3 Mim 32 MIKS2 61 2MN2S2 90 2MSNs 4 Msf 33 Az ez 3M SK 2 91 5 MF 34 L2 63 3MS2 92 6 203 35 T 64 MINK2S2 93 7 sigra 36 52 65 SNK2 94 2 MS s 8 Q 37 R2 66 2SK2 95 2MSKs 9 p rho 38 K2 67 2MS2N2 96 4MS10 10 O 39 MSN2 MQ 97 3M2S10 11 40 KJ 2 69 2MP3 98 AMSN z 12 M 41 2SMb 70 2MQ3 99 5MSi2 3 Xa chi 42 MO3 71 3MK4 100 AMpSiz 14 T pi 43 Ms 72 3MS4 101 MVS2 15 Pi 44 5 73 2MSK4 102 2MK2 16 S 45 Mis 74 3MIKs 103 MAz 17 Ki 46 Sks 75 104 18 Wi psi 47 MIN 76 3MOs 105 MSV2 19 1 phi 48 Ma 77 2 MN S6 106 SKMe 20 0 theta 49 SN 78 3MNS6 107 2MNS4 21 l 50 MS4 79 AMKe 108 MVa 22 50 51 MK4 80 4MSe 109 3MN4 3 OO 52 Sa 81 2MSNKe 110 2MSN4 24 OQ 53 Sky 82 2006 111 NA 25 MNS2 54 2MN6 3MSKe 112 NB 26 2N 55 Ms 84 4 113 MSOs 27 Hz vu 56 MSNe 85 3MSNs 114 MSKs 28 57 2066 86 MKLe 115 2MN gt 29 Vz nu 58 2MK
41. es became the most plausible It wesn t until Isaac Newton 1642 1727 and his law of gravitational attraction that everything fell into place Hewesthe first to correctly explain the soringneap gde and why equinoctial tides were larger than those at other times of the year Now tha tides were fully understood scientists started to look for methods to accurate y predict then for any date and time future and past Various methods have been devised for this and all start with having a good series of observed sealevds which are analysed to identify repeating patterns in thetide In 1832 Sir John Lubbock developed a method of analysis and prediction based on rdating the time and heignt of high and low weter to the time of Page47 lunar transit with corrections mede for lunar and solar dedination and distance However the method generally cons dered to be the most accurate for most but not al locations is caled Harmonic Analysis and Prediction The basis for harmonic analysis is that the tide can be represented bya finite number of simple harmonic terms each one a simple mathematical sine weve Each constituent either individually or in pairs corresponds to one of the astronomical phenomena to affect the tide Harmonic prediction involves amply calculating these harmonic waves for any point in time and adding the results together to get the overall tide Early development of Harmonic Analysis wes carried out by Laplace
42. gam Interaction with the program is done through the options on the program menu however more commonly used controls have a button on the toolbar to provide quicker access This screen also gives information on your licence and restrictions on the use of the software The first line gvesthe company name the software is licensed to Do not give copies of the software to other people as it will have your company name embedded within the software The licence duration isthe period for which predictions can be made Note that the softwere can be used outside of this period but it will only meke calculations for the years specified The third line specifies whether you have a standard customised or U serData licence see page 7 and whether this is a ingeuse licence or a network licence The last two lines specify whether the custom tide table feature is enabled see page 31 and whether you are licensed to use your own sets of harmonic constants with the software see page 37 Pagell Toolbar The buttons on the toolbar are ml sewe the prediction to a text file on the disk sl print the display currently on screen copy the prediction deta to the dipboard E aisplaythe mp set the input parameters for the prediction display the prediction in list formet display the prediction as atidetable IM display the prediction as a graph el l t laal scroll and zoom buttons about POLTIPS 3 Page 12 Using POLTIPS 3 This se
43. ght hand edge of the numbers as numbers are traditionally rigntaliqned In the illustration that shows the default values the date is right justified 26 of the wey across the box the times are 60 across and the hdqnts are 94 across Date V is the vertical positioning of the date It specifies the percentage down from the top of the box for the top of the date value This defaults to zero If you change the default fonts you will probably need to adjust these values to Page33 keep the data evenly spaced within the box It is best to play around with the rel ative positi oning values until you get something that looks good Title Lines Column Linesand Footer Linesare used to specify if you require lines drawn to separate the titles the columns of data and the footer This can be set to dndeline double line dashed line or no line Advanced tab Low Water Custom Tide Table Format 3 Font Appearance Advanced Port Name Shortname Long name Custom name AVONMOUTH Time Zone Text GMT GMT BST Datum Information C Shorttext Long text C Custom text Datum c s Chart Datum 6 50 me C Time Zone GMT BST Footer text Tides computed by POLT PS software developed atthe Standard Footer Proudman Oceanographic Laboratory The standard footer text must be used for all published tide tables This contains some of the more adva
44. ish Summer Time BST is not supported SL U o alti fe Bar npe ope Hp LISS l a SIMI 2 ENGLAND WEST COAST AVONMOUTH Tear ZONE Lae VN Leng PITW nis TRE JANUARY 2062 me 88280 yssssss zys Cap piight Samasa Rest As with thehich and low water tidetable the full width of the window is used meaning that you mey need to scroll up and down with the arrow keys or toolbar buttons to see the whole table When printing the hourly height tide table you must set the printer to landscape mode rather than portrait If you forget to change this you will get a warning message appear and printing will not continue until this has been changed Locations with unusual tidal characteristics Some ports experience unusual tidal patterns such as double high waters eg Southampton or double low waters eg Portland or Weymouth When POLTIPS 3 computes the high and low waters for such a port it may find that there are more than four turning pointsin any one day If this is the case the progam will display the following dialog box 2 One or more days has greater than 4 tides Would you like the program to try and remove these extra tides l If Yes is selected POLTIPS 3 will decide which are the primary high and low waters for the prediction and remove the extra ones If all the turning Pagel7 points are re
45. l items CD ROM licence disk and user manual is returned within thirty 30 days from the date of despatch from POL and provided that all seals remain intact No refund will be mede if the seal has been broken on any items 3 Thelatest vesion of POLTIPS 3 will be available to download from our web site 4 POL will endeewour to contact all registered custorrers preferably by email informing them that a new update has been placed on the web ready to download 5 POL will providetechnical support for POLTIPS 3 only to its registered users 6 VVedo not quarantee that the functions contained in POLTI PS 3 will meet your requirements or that the operation of the program will be either error free or appear precisely as described in any documentation describing POLTIPS 3 7 No responsibility can be accepted by NERC for any consequential loss or damage from any use that is made of POLTIPS 3 and output from POLTIPS 3 howsoever caused 8 All implied warranties terms representations and conditions induding by way of example only the implied conditions of satisfactory quality and fitness for any purpose of the information are excluded to the fullest extent permitted by law 9 ThisAgreement is governed by Engish law and the parties submit to the exdusive jurisdiction of the Engish courts Page4 Introduction The Proudman Oceanographic Laboratory The Proudman Oceanographic Laboratory POL isa component laboratory of the U K s Na
46. la 5 Minute Predictions for AVONMOUTH Time Zone GMT only 140 130 120 110 100 Predictions to Chart Datum When viewed in list view you gt 576 values however this is much easier to gasp when you look at it as a graph Notice that the intervals plotted on the time axis vary automatically depending on how much is displayed When viewinga month you only get the date of each Sunday displayed However with 2 daysin view you get every 6 hours Zoomin further and the graph will show every hour Formatting the graph view Many of the automatic settings on the gaph be changed for example you can remove the grey background from the graph for dearer printing Todo this select Output Format Graph From this di aog box it is possible to change various aspects of the graph the title along the top of the graph the text displayed along tine vertical Y axis the maximum and minimum velues for the vertical axis the interval for the time axis default is automatic o the size of the markers default is large whether you want gid lines shown on the graph e Whether you want the grey background on the gaph whether just markers just lines or both are used to display the graph defaults to markers only for high and low weters and lines only for interval predictions Page25 Format Graphical Output x Graph title 5 Minute Predictions for AVONMOUTH taxis
47. lled in automatically for you Then select the type of prediction you require from the choice of five types The default isto compute hich and low waters sometimes known as turning points however you select equal interval predictions and Page 13 List vievv specify the time interval in minutes default is 60 minutes You can also opt to just have the high waters the low waters or general tidal statistics for the location s page 21 Finally select if you want times adjusted for British Summer Time box ticked or to leave all timesin GMT UT unticked And that s it just dick compute and the results will be displayed in the Window If you sdected a long duration or you have a Slower computer you will see a progress indicator in the bottom left corner of the window and the calculation may take a few seconds Prediction POLTIPS v 3 1 lol x File Edit view Input Output Misc Help B N l kil Page 1 of high low water prediction for AVONMOUTH ime Zone GMT only Datum Chart Datum Date Time Level m 01 01 2001 04 48 2 78 01 01 2001 10 48 11 01 01 01 2001 17 12 2 85 01 01 2001 23 06 10 67 02 01 2001 05 23 3 11 02 01 2001 11 29 10 57 02 01 2001 17 51 3 18 02 01 2001 23 50 10 28 03 01 2001 06 05 3 43 03 01 2001 12 20 10 26 03 01 2001 18 39 3 46 04 01 2001 00 47 10 05 04 01 2001 07 00 3 69 04 01 2001 13 30 10 20 Prediction completeci When yo
48. lmanac publishers it Port name also has the option to Year 2001 generate tables of sunrise Cancel and sunset times either by selecting the port or spedifying the exact location in latitude and longtude and height above sea level To bring up the dialog box Page28 select Input Sunrise and sunset by port to select one of the coastal locations in POLTIPS or Input Sunrise and sunset by lak longto xil specify any location Location degrees d minutes Set the parameters in the dialog tude fo r and dick on the Compute Now Longitude p 4 b 5 i 7 a Year Height above sea level and sunset times will be 2001 b m displayed This be srolled in the same way as the tidetable using the arrow keys or toolbar buttons Sv 3 i lol x File Edit View Input Output Misc Help Bla almo Aliae s Sunrise and Sunset Times Times in GMT ABERDEEN Year 2001 January February March 1 08 47 15 36 1 08 08 16 36 1 07 02 17 40 2 08 46 15 38 2 08 06 16 38 2 06 59 17 42 3 08 46 15 39 3 08 04 16 40 3 06 56 17 44 4 08 46 15 40 4 08 02 16 43 4 06 54 17 47 5 08 45 15 42 5 08 00 16 45 5 06 51 17 49 6 08 45 15 43 6 07 57 16 47 6 06 48 17 51 7 08 44 15 45 7 07 55 16 50 7 06 46 17 53 8 08 43 15 47 8 07 53 16 52 8 06 43 17 56 9 08 42 15 48 9 07 51 16 54 9 06 40 17 58 10 08 41 15 50 10 07 48 16 57 10 06 38 18 00 11 08 40 15 52 11 07 46 16 59 11 06 35 18 0
49. monic constituents each directly tied in with astronomical influences on the tide Highest and Lowest Tide HAT and LAT The Hignest and Lowest Astronomical Tides are the highest and lowest leves that will normally be reached under normal meteorological conditions To calculate this the maximum and minimum values are taken froma continuous 19 year prediction POLTIPS 3 uses basic knowledge of the tides to reduce the time taken to compute HAT and LAT byonly predicting the tides around the spring and autumn equinoxes for the years from 1997 to 2015 both known yeers of extreme tidal levds See also the entry on Extreme Leds High and Low Waters thetimesin thetida ode when the tide reaches its maximum and minimum height respectively The time between successive high waters or successive low waters is about 12 hours 25 minutes for UK ports High and low weters are collectively known as turning points as it is the point in the cde when the tide turns from ebbing to flooding or vice versa Hourly Heights atypeof tidal prediction where the height of thetideis computed at an hourly interval in time and not just for the point of high and low weter Mean High Water Neps MHVVN the average level of high water during periods of neap tides Mean High Water Springs MHWS the average leve of high water during periods of spring tides Mean Low Water Neaps MLWN the average level of low water during periods of neap tides
50. nced settings Port Name will let you select between ather a short name the long name or custom text of your choice Examples of this Short name AVONMOUTH Long name ENGLAND WEST COAST AVONMOUTH Custom Avonmouth Port of Bristol The default is for long port name to be sdected Only the standard ports in POLTIPS 3 have a long port name If this is sdected for a secondary port the short name will be used Datum Information also has the option of short text long text and custom text The long text which is the default g ves the datum selected rdative to the other prind ple datum For example Short text Datum of Predictions Chart Datum Long text Datum of Predictions Chart Datum 6 50 metres bdow Ordnance Datum New yn Custom CHART DATUM 6 5m below Ordnance Datum NOTE Be wary of using custom datum statements in case you specify incorrect information Page34 Time Zone Te allows you to select between the following two formets Sdected Displayed if BST not Displayed if BST selected selected GMT GMT BST GMT GMT BST Time Zone GMT BST TimeZone GMT only Time Zone GMT BST Note that the text displayed is based on whether BST wes selected when the prediction was mede and not on which months are displayed on screen For example if you predict a whole year with BST sdected and opt to display two months per pags page one which wil contain January and February p
51. nd other horizontal datums exist Ordnance Datum Belfest O DB for Northern Irdand Ordnance Datum Dublin ODD for the Republic of Irdand and Ordnance Datum local ODL for more remote locetions European locations have their own landdeveling datum Datums in POLTIPS 3 When making a prediction in POLTIPS 3 the default datum is always Chart Datum unless a pedal datum is specified for the port usually given in the port name For most locations you can switch betw n Chart and Ordnance datum by selerting Output Datum and choosing the one you require The currently 32 eted datum is displayed on both the list view and the tidetable view Formatting the List View One of the main uses of xi the list viewis for getting Date separator Time separator p Field separator 2 R FE thetide data into another x 6 2 spaces R y n space Windows application such C space ert 2 1 space as Microsoft Excel C tab C none spreadsh t To allow for MOR danla Em ere pay Leading zero on dates OK more flexibility Asnumber isadi E ok v Leading zero on hours POLTIPS 3 will let you 55 Cancel change some aspects of this by sdecting Output Format List View Thisisonly available when the list view is selected for the current prediction This dialog gives you the capability to change the date and time separator characters and the field separator the characters between the date and time and the time and height Yo
52. ndard version are not licensed to publish the data in any form induding on the nternet however the tide tables can be distributed free of charge within a membership dub eg a sailing or fishing dub U srs cannot use the custom tidetable layouts or their own harmonic constants with the software Althougn the accuracy is dightly reduced compared with the customised version it is still suitable the majority of applications For consultancy or eng n ring use we recommend the customised version The customised version of POLTI PS 3 is purchased on an individual port basis with either a two or three year licence Usersare pernitted to publish the tide tables for resale in any number of books for which they own the complete copyright i e users cannot purchase this software and then sel the results on to third party publishers without written permission from POL See also the restrictions on Internet publishing bdow Userswill also be able to use the custom tide table layout and use their own harmonic constants subject to the same 2 or 3 year licence The UserData version of POLTIPS 3 is provided without any data sets It is for use by users who want to compute predictions using their own harmonic constants and is usually sold with a 10 yeer licence Publishing tidal prediction on the Internet Only users of the customised and U serData version of POLTIPS 3 can publish the results on the nternet Thisislimited to one month in advance
53. ngs for use with other tide tables for different years or locetions Sdect Page35 Output Save Custom Tide Table Formek and specify afilenamein which all the settings will be stored for later use When you use the program at a later date you cen calculate your tidal prediction as normal and then rd oad your tide table layout again using Output Select Custom Tide Table Format Custom Tide Table layout files use the file extension ctt Note that any custom datum statement or custom port name is not saved as part of the tide table layout If the layout wes applied to a prediction for a different port this information would be wrong Page36 Using your ovvn harmonic constants U sers of the standard version of POLTIPS are not licensed to use their own harmonic constantsin the program This feature will usually be disabled check the title screen of the program Do not attempt to use your own harmonic constants in the software unless you are confortable editing text files on your PC e are familiar with the basic concepts of harmonic prediction About Harmonic Constants The basis of all tidal predictions is a set of harmonic constants for the location of interest With these and the appropriate mathematics for calculating various astronomical parameters it is possible to predict the tide for any date future or past For more information on harmonic constants read the section in the Frequently Asked Questions about Tides pag
54. o the of the sun 12 25 14 164 cyde due to the gravity of the moon e 24 00 and 24 50 28 328 cycles caused by the differences in the two tidal bulges 27 2122 day gde caused by change in lunar dedination Moons andeto the Earth 27 5546 day caused by a regular change in the Earth Moon distance 29 5306 day oyde caused by the phases of the moon see question 8 Each of these cydes is cled a tidal harmonic constituent and POLTIPS uses in excess of 100 of themin calculatingatidetable You can see that the length of these cydes is known very acuratdy to the nearest 1000 of a second Therefore it is easy to find them in a sequence of observations using a method called tidal analysis Once each constituent is identified its size amplitude and time of arrival phase is tored These two values known as a harmonic constant are unique for every location The amplitude and phase for each constituent combined with the fixed sp d of that constituent allows us to predict its contribution to the Overall tide forward or backward in time almost indefinitely Adding up the effects of all the constituents at a given location lets us predict the overall tide at any timein the future or past Most tide tables just list the time and height when the water isat a maximum and minimum level in each tida ode Thisleads to approxi mately 2 hign waters and 2 low waters every 24 hours 50 minutes or 4 tides a day on most day
55. of data and services it offered wes greatly expanded to indude the results of the latest POL scientific research However oceanographic research tends to produce vest amounts of raw data with little meaning to anyone other than atrained oceanographer The Applications Group Page5 mission isto provide a valueadded service which includes ensuring that the customer gets the data they require in a form that is easily understood This is achieved by creating visual isetions of the data fully documented reports or by processing the raw data to derive new data sets that are of more value to usersin the real world The Applications Group also develops software that allows users to buy raw data that remains hidden behind a friendly user interface and carries out all the processing necessary to produce attractive and informative displays which cen be eesily printed or exported into other softwere POLTIPS 3 tidal predictions software POLTIPS is one such product developed by the Applications Group First releesecd in 1993 as a DOS product for PCs its success has led to successive refinements and the inevitable move to the Windows environment The third and latest version of POLTIPS is by far the most powerful and user friendly version to date Hidden behind the simpleto use interface is a powerful mathematical eng ne for computing the tides combined with sophisticated graphical layout tools for producing tide tables and graphs of
56. plication Provided the program supports text input the data should appear in the application Tidal Statistics From the Tidal Predictions input dialog box you can select to have POLTIPS 3 compute some general statistics about the tide at the selected locetion Page21 Tidal Predic 3 E x Port Name r Start date AVONMOUTH 1 zi 1 2001 ABERYSTWYTH ALBERT BRIDGE m End date ALDEBURGH ALDERNEY BRAYE 31 fiz 2001 ALLINGTON LOCK m m zi ALLOA AMBLE 7 day This Month This Year AMLVVCH d n ANNAN VVATERFOOT ANSTRUTHER EASTER APPLECROSS C High and low waters ARBROATH C Equelintervel V f mins ARDNAVE POINT High waters only m Type of prediction C Low waters only ARKLOW R i Click this Statistics option X Cancel Show on map T Adjust for British Summer Time BST Standard port Computing tidal statistics can take up to 30 seconds on a Pentium 200MHz PC File Edit View Input Output Misc Help S al el lri ialal el Tidal Statistics for AVONMOUTH Latitude 51 30 N Longitude 2743 W Port details Standard port Datum of Predictions Chart Datum 6 50 metres below Ordnance Datum Newlyn Highest Astronomical Tide HAT 14 65 metres HAT occurs at 08 50 GMT on 21 02 2015 Lowest Astronomical Tide LAT 0 21 metres LAT occurs at 15 05 GMT on 10 03 1997 Maximum Tidal Range possible 14 79 metres High Wate
57. quired then select No and all theturning points will be displayed Note that the tide table view cannot display more than 4 tides per day so you Will only see the first four tideson each day Warning If you deddeto remove the extra turning points a series of rules are used to try and identify which are the main hich and low waters These rules will work more rdiably if the prediction is for a period of at least 21 days However POLTIPS 3 still get it wrong for some locations which have a very complex tidal pattern eg Poole Weymouth and it is advisable to check that the correct tides have been removed by looking at a graph 5 Minute Predictions for POOLE TOWN QUAY Time Zone GMT only Main High VVater Triple 2 25 L S the firstione POLTIHS continueb to use thelfirst high water gt high water although novv the sebond E 00 ig the more significant 1 50 o Q o 0 50 0 25 0 00 13 1 2001 15 1 2001 17 1 2001 19 1 2001 The illustration above shows an example of when POLT IPS 3 has identified the first high water as the significant one but a few days later the second high water has become the more significant one At one point on the 19 January there is even a third high water To manually heck to see if POLTIPS 3 has removed the correct tides you should print out the results with the extr
58. r Spring MHUS 12 75 metres High Water Neap MHUN 0 69 metres Low Water Neap MLUN 4 16 metres Low Water Spring MLUS 1 09 metres Type 0 02 semidiurnal Shallow Water Influence 0 08 Selected Period 01 10 2001 to 31 10 2001 Highest Tide in this period 14 26 metres Lowest Tide in this period 0 30 metres Largest Tidal Range in this period 13 96 metres Average Flood time 5 hours 52 minutes Average Ebb time 6 hours 32 minutes Quickest Flood time 5 hours 20 minutes NM 2 Page22 The informetion calculated is Position the latitude and longtude of the port if available Port details Usually tates whether the port is a standard port with harmonic constants or a secondary port based on time and height differences vvith the reference standard port Datum of Predictions The height of Ordnance Daum rdative to Chart Datum and a description of how the Ordnance Datum 15 defined Highest Tide HAT the highest level thetideis likely to reach under normal meteorolodcal conditions and the date this occurs between 1997 and 2015 see dossary Lowest Astronomical Tide LAT the lowest level thetideislikdy to reach under normal meteorological conditions and the date this occurs between 1997 and 2015 see dossary Madmum Tida Range posible the largest difference that occurs between one high water and its adjacent low water during the period 1997 to 2015 Mean High Water Springs M
59. re called neaps Spring tides happen just after every full and new moon when the sun moon and earth arein line That s when lunar and solar tides line up and ranforce each other making a bigger total tide Nep tides occur when the moon isin the first or third quarter when the sun earth and moon forma right ange Thelunar high tide coinddes with the solar low tide and they partly out gving a smal total tide Because of the regular motion of the sun moon and earth spring tides occur roughly 36 to 48 hours after the full or new moons and for any gwan location always at roughly the same time of day For example at Liverpool the spring tides are generally around midnight and midday Not all spring tides are the same size Springs nearest the equinoxes 21 March and 21 September when day and night are of equal length all over the world are sligntiy bigger The explanation for this is very complex and won t be gven here Worldly Effects Back on earth tides are affected by more mundane things such as weather and the shape of the coastline In the upper reaches of estuaries the riverbed and shape of the estuary can distort the tidal pattern producing long flood times and short ebb times Though the time from hich tide to high tide isthe same usual rougnly 12 hours 25 minutes low tide is not half way between them At some places the flood tide rises quickly after a period of low water lasting maybe four or five hours
60. redictions will display GMT BST even though BST does not start until March Thisis for consistency across all pages of the tide table Footer Text enables you to change the line of text that appears bd ow the datum statement at the bottom of every page This defaults to the standard POL copyright message Although this can be changed within the program the condition for publication of tide tables produced by POLTIPS 3 is that it must have the standard copyright message in the footer If you change the footer text you will get the following warning when you dick OK IMPORTANT NOTICE x You have changed the footer text on the tide table Please note that you cannot publish tide tables without the standard footer text unless you have written permission from POL If you wish to publish tables without the standarci footer text you must first s k written permission from the Applications Group t POL All the settings are retained between predictions so if you set up a tide table layout you like you can predict multiple ports or periods of time and retain the settings If you want to use the layout at alater date you will need to save the settings to a file on disk see bdow Custom port name and custom datum statement changss are not stored between predictions as this information could potentially be wongif a new prediction is made Saving your tide table settings Once you get a tide table layout that you like you can save your setti
61. s very important see table belovv Characters Description 1to31 Short port name mex 30 characters 32 Port type 1 standard port induded by POL 2 secondary port using timey height differences 4 port created with users own constants 33 to 36 Number to indicete how to find the correct data for the port If port type equals 4 this number istheline number in the USERCON DAT file were the data for this port starts 37 to 41 If port type equals 1 or 4 it indicates whether this port is proneto double high value of 1 or double low value of 2 waters If unsure leave this Vaueas zero If port type equals 2 it is used to indicete the reference port 43 to 122 descriptive text optional however 80 spaces must be typed if no text is supplied This is displayed in the input dialog box when a port is sdected 123 to end of line long port name used by default on the hourly height tide table and optionally on the custom high and low waters tide table format max 72 characters Normally only standard ports have a long name although one could be added for any port in the index file As the padng of the information must be precise use an existing entryto line up the different pieces of information when inserting your own entry into theindex file USERCON DAT at This file is used to store all your own sets SAMPLE M2 ONLY of harmonic constants that you will want 3 000 to
62. s with 3 tides on every 7 or 8 day 15 W here can I find out more information about tides There are many books that cover the subject of tides but the reader should be awere of inaccuracies that often exist You should avoid books that talk about the second bulge on the far side of the earth being caused by either the moon s gavity pulling the earth away from the water or bythe spin on the Earth on its axis The daily rotation of the Earth on its ais has no effect on tides See page 52 If gravity is always pulling towards the moon What causes the bulge on the opposite side of the earth One excdlent book on the subject Tides Surges and Mean Sea Leva David T Pugh Published by John Wiley and Sons 1987 ISBN 471 91505 X It covers the subject in immense detail but is very mathematical and rather expensive to buy Page56 Glossary Dahums see section on Datums on page 19 BST seeTime Zones bdow Diurnal Tides tidesth t have only one high water and one low water every 24 hours 50 minutes This does not occur in UK waters Ebb Tide the seevverd tidal flow from high water to low water The Ebb time isthe time between a hidh water and the following low water Equinoctid Spring Tides the spring tides that occur doses to the pring equinox and autumn equinox Thetidal effect due to the sun isat a maximum since the dedination is zero These usually have the largest tidal range of the year i e the highest hich
63. se are not easily predicted requiring accurate weather forecasts and complex computer models of the sees and oceans Tide tables do not induded predictions of the surge and explains why they may differ from what is observed See question 1 of the Frequently Asked Questions page 51 Tidal Analysis the process of trating the amplitude and phase of each harmonic constituent from a period of tidal observations froma tide gauge This crestes a unique set of harmonic constants for that location Tidal Range the difference in height between high water and an adjacent low water Asthisisnot constant it is usually quoted as one of thefollowng men tida range the average difference between high water and adjacent low water mean spring range the average difference between Mean High Water Springs and Mean Low Water Springs e mean neap range the average difference between the Mean High Water Neaps and Mean Low Water Neaps TideType specifies whether the tide is semidiurnal diurnal or mixed The equation below is used to calculate a value that is used to decide this Value Tide type O K 0 0 to 0 25 Semidiurnal Value M45 1025to15 Mixed mainly semidiurnal 7 11 5t03 Mixed mainly diurnal greeter than 3 Diurnal Page59 Time Zones Tidal predictions aretraditionally mede to Greenwich Men Time also called Universal Time Thisisthe local timefor all UK ports However the UK switches to British Summ
64. source is a Scandinavian word meaning to leap Another possibility is that it is related to the natural feature of a spring which is a place where water wals up from the earth 10 W here are the highest tides in the world Burncoat H ead in the Bay of Fundy Canada has an average spring tidal range of 12 9 m The second largest tides in the world occur at Avonmouth in the Bristol Channd where the average spring range is 12 3 m The average spring tidal range is the average difference between high and low weters during spring tides Page54 11 Do the tides follow a repeated pattern No There are simil rities for example every 18 6 years we experience larger than average tides but they never actually repet 12 When during a year can we expect to find the largest tides A day or two after the full or new moon nearest to the equinoxes The spring equinox is usually the 21s March and the autumn equinox the 23rd September Some years have tides that are notably higher than other years 1997 wesa Sqnificant year as will be the year 2015 For really favourable conditions you Will haveto weit around until the year 3182 Even then thetides may only be 1 or 2 amhicher than in 1997 13 Do the planets have any affect on the tides The tidal force generated by a body in space is based on two things its mess and its distance from the earth and it isthe latter of these that is far more significant The nearest approach
65. st Predictions for such locations are computed by meking a prediction for a nearby mein port and then applying time and height differences to the high and low weters Each secondary port has 4 separate time differences depending on whether high or low waters are being predicted and on the time of day There are also 4 height differences for mean high and low water springs and neaps Equal interval predictions cannot be computed for secondary ports Conventions used in this manual File b Print means fromthe File menu select Print abcdefg memsyou typethis text in be x means hold down the shift key and press X cow x means hold down the control or ctrl key and press X Pages Installing and starting POLTIPS 3 How to install POLTIPS 3 Please read before installation Before installing POLTIPS 3 on your system please ensure that you have the CD andthe licence floppy disk If ather is missing contact the Proudman Oceanographic Laboratory Insert the POLTIPS 3 CD into your CD ROM drive TheCD should automatically run the installation program If this does not start after 20 seconds you will need to run the progam manually as explained below Click on Start and sed Run In thedialogbox type d setup Whered isthedrive letter of your CD ROM and dick OK Followthe on screen instructions Part way through you will be asked to insert the floppy disk containing the licence into your floppy disk driv
66. t it is a bit stronger on the surface of the earth facing the moon near side and weaker on the far side This means that on the near side the moon tends to pull anything that s free to move towards it In the same way on the far side there isn t quite enough gravitational pull so that anything that s free to move tendsto fly off away from the moon course though land isn t free to move the oceans are So on the n r side they are pulled into a bulge towards the moon and on the far side they pile up into a bulge awey from the moon Astheeerth pins different parts of the world move under the two bulges of high water and experience high tides gving the familiar two tides a day semi diurnal tides around Britain In some parts of the world local Page43 effects can mean only onetide a day diurnal tides for example in the South China Sea and parts of North Australia or even no tide t all Between the two bulges are two troudhs of low water produd ng two low tides a day The sun also creates a very similar though smaller effect the solar tide and it is the interaction of the lunar and solar tides that causes spring and neap tides Springs and Neaps Tides change in height with low water level and high water level varying throughout the month The tides build up to a maximum and fall to a minimum twice a month The tides with the biggest difference between high and low water are called pring and those with the smallest a
67. tural Environment Research Council NERC POL is based in Bic amp ton on Meeseysi de t thedd d rvatory Thenew Proudman building wes constructed in the nid 7Os to house the rapid of staff POL has provided a national and international tidal prediction service since 1924 in fact the modern methods of tidal prediction used throughout the world are based on the work of Dr Arthur Doodson in the 1920s and who later became Director of the laboratory Since then POL has continued to devdop and refine the analytical methods used to compute the tides Coupled with advances in modern computer hardware and softwere we now have the most accurate tidal prediction software available As the laboratory responsible for the installation maintenance and running of the UK s National Tide Gauge Network we have access to the most accurate and uptodate data which we utilise to derive harmonic constants used in the computation of tide tables Although some methods of tidal prediction use only a few harmonic constituents the Proudman Oceanographic Laboratory uses up to 150 harmonic constants for some main ports hence producing what POL bdieves to be the most accurate tidal predictions available The Applications Group The Proudman Oceanographic Laboratory has ance the 1920s had a team of tidal experts produce tide tables for organisations all over the world In 1992 the goup wes renamed the Applications Group and the range
68. u can also specify whether the month is displayed as a number or 3 letter abbreviated word and whether you Page20 require leading zeros on the dates and time only the hours as the minutes always use a leading zero The options set in this dialog box are also used when tide data is copied to the clipboard or saved into a text file see the next section Saving tidal data to disk or the clipboard Althoug POLTIPS 3 has a powerful and sy to use set of features there mey be times when you need to export the data into another Windows application POLTIPS 3 gives you two vveys to do this save the list View to a text file on your hard disk e copy and paste via the dipboard Saving a file to disk Make your prediction as normal and ensure that you have sdected list view Make any changss to the layout using the Format List View dialog then sdect either Sene as Tet File dick on the save button on the Enter the filename and dick the save button to save the prediction to disk This can now be loaded into any Windows application that will read in a plain ASCII text file eg notepad Word Excel Using the Clipboard A quicker way of getting data into another application is to usethe Windows dipboard Make your prediction as normal then select Edit Copy dick the copy button on the toolbar Esl or type em C Now simpiy switch to the application you want to put the tidal data into and select pashe from the edit menu of that ap
69. u make a prediction it is aways initially displayed in what is called the list view see picture This gives one high water or low water per line As high waters and low waters always alternate unless you selected high waters only or low waters only in the dialog box it should be obvious which isa high water and which is alow water To scroll up and down through the prediction use either the page up and down keys on your keyboard the up and down cursor keys or the up and down arrows on the toolbar At anytime you can switch back to the list view from one of the other Views using Output List View or dickingthe toolbar button Page14 If you save a prediction to disk or copy it to the dipboard it isthelist format that is useci even if you are viewing another format on screen You can also choose to print the data in this format however for any duration longer that a week or two it would generate quite a few pages of output A moresensible format for printingis the tide table formet Tide table view The tide table view outputs the prediction in a more traditional tide table layout as shown below and is sdected with Output Tide Table or dickingon the tide table toolbar button E Z xi Fle Edt Www pt Output Hep oqsa l a MTN lerias 2 GMT Datum Chart Datum Year 2001 January February Time m Time m Time m Time m 1 0448 278 1 6 0601 2 05 1 0537 2 80 1 6 0030 10 34 1048 11
70. ut Output Misc Help l l 2 BINION llaa As you zoomin more ports will be displayed and the zoomlevel will be displayed in the status bar along the bottom of the window as Zoom level 1 through to Zoom leve 5 all ports shown Fie Edt View Input Output Misc Hep Bio ifa 1 11s1 dala 13 Zoom Level 4 most ports shown The reason for the blue shaded crosshatching is to indicate the largest square area that can be digolayed in the window This allows consistency between the screen and printouts as the non shaded area is the only part guaranteed to appear on both It also remains consent as the window is resized Page27 Selecting a port for prediction To usethe map to select a port zoominto the area so that the port name is visible and dick on the small diamond next to the port name with the rit mouse button TheTidal Predictions dialog box will appear with the port name dready sd ected Showing the location of a port on the map If you have the Tidal Prediction dialog box on screen and went to locate where a particular port is select the port from the list and dick on the Show on Map button The dialog will disappear and switch to the map view with the selected port centred in the window and the zoom level st appropriately to show the surrounding ports Sunrise and sunset times As POLTIPS is used by Sunrise and sunset times xj some a
71. yping mistakes In 1977 the institute wes renamed yet again to the Proudman Oceanographic Laboratory in honour of Professor Proudman It continued to develop its world enowned reputation in tidal prediction by developing new analytical methods for locations that had a reputation for being difficult to predict accurately By this time ocean research had moved on to encompass the much harder to predict surge component of sen level the change in level due to meteorologicel effects such as wind and atmogpheric pressure The Page49 computer model run twice a day at the UK Meteorological Officeto predict surges around the coat was devel oped by sdentists at POL In 1992 the Tidal Computetion and Statistics Section became known as the Applications Group and the work branched out to indude offshore tidal predictions based on sophisticeted computer simulations of the worlds sess and oceans In 1994 the first version of the POLTIPS tidal prediction package wes rdeesed for the PC and could predict a yearly tide table in less than 10 minutes The latest Windows version of the software to which this user guide accompanies can cerry out the same task in less than 5 seconds on a typical modern PC It isincredible to think how far we have come over the last 80 years with the help of computing technology And even though we know alot about the tides wearejust begnningto fully understand the other processes that go on within our sees and oceans

POLTIPS-3 User Guide - National Oceanography Centre

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