MARS CLIMATE DATABASE v3.0 USER MANUAL
Contents
1. 111 31 deg Local Time 16 22 Mars hours Temperature 218 4 K Pressure 5 303E 02 N m 2 Density Low Avg High 1 224E 02 1 269E 02 1 315E 02 kg m 3 Departure COSPAR NH Mean 211 18 1 HLS 1 x Density perturbation 0 84 of mean value Eastward Wind 2 5 m s Northward Wind 5 5 m s Time rel to TO 0 0 sec 0 000 sols Ls 98 9 deg Height 10 00 km 13 45 km Scale Hgt H p 9 96 H rho 9 96 km Latitude 22 000 degrees West Longitude 48 000 degrees Sun Latitude 25 00 deg Mars Orbital Radius 1 640 AU Sun Longitude 111 31 deg Local Time 16 22 Mars hours Temperature 193 8 K Pressure 2 055E 02 N m 2 Density Low Avg High 5 279E 03 5 529E 03 5 1 79E 03 kg m 3 Departure COSPAR NH Mean 18 4 14 5 10 7 Density perturbation 0 16 of mean value Eastward Wind 9 5 m s Northward Wind 3 4 m s Time rel to TO O O sec 0 000 sols Ls 98 9 deg Height 20 00 km 23 45 km Scale Hgt H p 8 98 H rho 8 98 km Latitude 22 000 degrees West Longitude 48 000 degrees Sun Latitude 25 00 deg Mars Orbital Radius 1 640 AU Sun Longitude 111 31 deg Local Time 16 22 Mars hours Temperature 174 7 K Pressure 7 O71E 01 N m 2 Density Low Avg High 2 008E 03 2 103E 03 2 198E 03 kg m 3 Departure COSPAR NH Mean 23 6 5 20 0 5 16 4 5 13 list user specified filename Mean density High value of density Low value o2. wind Meridional North South wind Atmospheric density Boundary layer eddy kinetic energy Table 1 Variables stored in database mean data files Standard deviation 2 D or 3 D CO ice cover sdco2ice kg m Surface emissivity sdemis none Surface temperature sdtsurf K Surface pressure sdps Pa Atmospheric temperature sdt K Zonal East West wind sdu ms Meridional North South wind sdv iis 3 Atmospheric density sdrho kg m Table 2 Variables stored in database standard deviation data files 4 2 e The data in the MCD are written using the Data Retrieval and Storage DRS library developed for the Program for Terrestrial Climate Model Diagnosis and Intercomparison or PCMDI see Detailed Design Document for more details The library available from the Lawrence Livermore National Laboratory World Wide Web server http www pcmdi llnl gov drach DRS html is provided on CDROMA1 along with the database See below some instructions on how to install the library if it is not yet available on your system DRS works on the following systems DEC ALPHA HP IBM NSL SGI SOL SUN Os and Solaris UNICOS We also recommend that you install the Grid Analysis and Display System GrADS which is an excellent system for displaying graphical output from geophysical datasets GrADS can read DRS files and display their contents us ing a few easy instructions GrADS can be down loaded from the Institute for Global Env
3. 266 2 266 8 267 3 Emissivity 0 95 0 95 0 95 CO2 Ice kg m 2 0 0 0 Pseudo height 10log sigma 40 Pseudo height 10log sigma 100 120 140 Tempercture K 160 180 200 220 2 40 03 0 035 0 04 0 045 0 05 0 055 0 06 0 065 0 07 Std Dev Mean Density Pseudo height 10log sigma 80 60 40 Pseudo height 10log sigma 200 180 160 140 120 100 80 60 40 Zonal Wind m s 20 0 20 10 10 Meridional Wind m s Figure 1 Sample output from pro der 1 site file gs an afternoon profile at the Viking Lan 20 MCD MCS dust Ls 90 120 Profile location lon 00 lat 75 local time OOhrs Mean data with confidence limits at 1 standard deviation Surface Pressure Pa 447 462 477 Surface Temperature K 145 6 145 8 146 Emissivity 0 85 0 85 0 85 CO2 Ice kg m 2 447 498 549 80 80 Pseudo height 10log sigma Pseudo height 10log sigma 40 40 204 el d E 20 126 129 132 135 138 141 144 147 150 153 0 03 0 04 0 05 0 06 0 07 0 08 0 09 0 1 0 11 0 12 0 13 0 14 Temperature K Std Dev Mean Density 140 140 g 120 g 120 E E SI gr a a 100 100 2 2 eo eo l l 80 80 D D pe 2 o o 60 o 60 2 2 o o 5 E o 40 o 40 a a a a 20 20 20 0 20 40 60 80 100 120 140 160 180 50 40 30 20 10 0 10 20 30
4. CD ROM is mounted at the time of running the program CD ROM 1 for access to the MGS and dust storms dust scenario and CD ROM 2 for the other dust scenarios if the CD ROM is mounted as dev cdrom then create the link ln s dev cdrom data EMCD DATA This link is required by the mcdgm program as it stands see 5 3 In the at memcd subroutine the path to the directory can be set using the dset variable eg dset dev cdrom data although by default the subroutine will use EMCD DATA if dset is not initialized or setto 5 If DRS is not available on your system you must install the DRS library a In the drs 1ib directory type make f Makefile machine where machine is either SUN HP UNICOS IBM or SGI for example make f Makefile SUN b Edit Makefile machine to set values for INSTALL LIB direc tory to contain libdrs a and INSTALL INC directory to contain the in clude files usually the same c type make f Makefile machine install d In the emcd directory edit Makefile to initialize the variable DRS_INC and LIB DIR with the address corresponding to INSTALL LIB and IN STALL INC respectively More information can be found in drs lib README and in the DRS docu mentation in drs doc Because It was desirable to declare all the variables used in drsdef h one of the include files supplied with the DRS
5. F N Cunnold D M Jeffries W R III and Johnson D L 1995 The NASA MSFC Global Reference Atmosphere Model 1995 Version GRAM 95 NASA Technical Memorandum Lewis S R and Collins M 19992 Mars Climate Database v2 0 User Manual Eu ropean Space Agency Technical Report Lewis S R and Collins M 1999b Mars Climate Database v2 0 Detailed Design Document European Space Agency Technical Report Lewis S R Collins M and Forget F 2001a Mars Climate Database v2 3 User Manual European Space Agency Technical Report Lewis S R Collins M and Forget F 2001b Mars Climate Database v2 3 Detailed Design Document European Space Agency Technical Report Lewis S R Collins M Read P L Forget E Hourdin E Fournier R Hourdin C Talagrand O and Huot J P 1999 A Climate Database for Mars J Geophys Res 104 24 177 24 194 Read P L Collins M Forget F Fournier R Hourdin F Lewis S R Talagrand O Taylor EW and Thomas N PJ 1997 A GCM climate database for Mars For mission planning and for scientific studies Adv Space Res 19 1213 1222 24
6. and a larger variance capture There have also been numerous small improvements and error corrections to the climate database access software since version 1 0 was released which are now all incorporated into version 3 0 3 Contents of the Mars Climate database The contents of each subdirectory of the MCD are summarized here docs This directory contains files in various formats which can be used to print further copies of the documentation User Manual user manual ps or pdf of the database V3 0 Detailed Design Document detailed design ps or pdf of the database V3 0 Programmer s guide for the atmemcd FORTRAN subroutine program guide ps pdfor doc Postscript or pdf versions of the scientific reference articles Lewis et al 1999 and Forget et al 1999 describing the Mars climate database V1 0 and the General Circulation models used to compile it are also provided emcd This contains FORTRAN source code for the climate database access softwares see Sections 5 3 and 5 2 and the README file in the directory the ATMEMCD subroutine the MCDGM interface and a test program Also included is sub directory testcase containing a simple tool to test the results from the soft ware after installation grads Some sample GrADS scripts which plot MCD data see Section 5 5 data The full MCD dataset derived from model runs The database is split between 2 CD ROMs CD ROM 1 includes a directory data cont
7. in FORTRAN or C by using the DRS library This gives the most flexibility for particular applications e g when one wantto handle global fields although it does demand a greater understanding of how the database and variability models if they are required should be used Some examples of programs included in atmemcd F or mcdgm F source files which open and read the database files are given along with some useful general purpose routines Fourthly control files instructions and example scripts in the mcd grads sub directory are provided for accessing the database using GrADS GrADS is a freely available package for access manipulation and display of earth science data which runs on many computing platforms This provides a very easy method of examining and plotting mean and standard deviation data from the MCD in a variety of formats It is not straightforward at present to use the variability model or orographic wave model from within a GrADS script though GrADS or any other visualization package could of course be applied to the output from either of the first two access methods when these features are required A second disadvantage is that GrADS requires a uniform vertical grid Since the database has been stored in terrain following o levels c p ps where p is the pressure and p is the surface pressure which varies as a function of position and time in order to retain the model s high resolution near the surface this means th
8. observations and the physi cal laws which govern the atmospheric circulation and surface conditions on the planet The MCD contains simulated data temperature wind density pressure radiative fluxes etc stored on a 5 x 5 longitude latitude grid from the surface up to an approximate altitude of 120km above 120 km pressure and density can be estimated using the database access softwares Five dust scenarios have been used with three main scenarios which provide data throughout the Martian annual cycle 1 a best guess thought to represent the moder ately dusty planet Mars as observed by Mars Global Surveyor without the major dust storms 2 a very clear year and 3 a relatively dusty year made by generalizing the Viking Lander dust opacity observations to the entire planet outside the dust storm periods The second and third annual scenarios are provided to bracket the possible global conditions on Mars outside global dust storms which are thought be highly vari able locally and from year to year The final two scenarios 4 a moderate global dust storm and 5 an intense global dust storm are provided during the period during which such global events are known to occur Fields are stored 12 times a day for 12 Martian seasons to give a comprehensive representation of the annual and diurnal cycles The user is referred to the Detailed Design Document for further information and the published article entitled A Climate Datab
9. one value of a 3 D field from the MCD Uses trilinear interpo lation to translate the database fields to the user specified longitude latitude c level and time The subroutine get si can be called first to translate geometric height into the c levels used in the MCD profi Reads a vertical profile from a 3 D field on model c levels Uses bilinear interpolation to translate the database fields to the user specified longitude and latitude and time get si Solves the hydrostatic equation to find the value of o the MCD vertical coordinate corresponding to the user specified height above the surface height Conversion between radius from the centre of the planet height above the zero datum areoid and height above the local surface Given any one of the above this routine finds the other two mars ptime This routine converts local time at a particular west longitude and turns it into database prime meridian time universal time e eofpb This routine computes a large scale EOF perturbation to a variable den sity surface pressure temperature zonal wind and meridional wind grwpb This routine computes a small scale gravity wave perturbation to a vari able density temperature zonal wind and meridional wind 5 5 Using GrADS GrADS can be used for simple manipulation and display of mean and standard devia tion data from the MCD and for more complicated calculations of derived quantities e g vorticity GrADS can also be useful for
10. quickly translating portions of the DRS format files into other formats 17 N B Some GrADS routines in particular hdi vg and hcur1 which compute hor izontal derivatives assume that the data relates to the Earth if they are used for calcu lating derived quantities from the database results from them should always be multi plied by a factor of approximately 1 88 to account for the relative radii of the Earth and Mars The dates used for the GrADS scripts are in Earth format and are arbitrary but the universal time of day is correct with one hour corresponding to 1 24 of a Martian Solar day a Martian Solar day is 88775 2 seconds so here 1 hour is actually about 3699 seconds In the database 00 00 is midnight and 12 00 is noon at 0 longitude in True Solar Time A simple interactive GrADS session to plot the seasonal average surface tempera ture for season 4 from the Viking scenario simulation may run like this ga open viksO5me Scanning description file viksO5me Data file viksO5me dat is open as file 1 LON set to 0 360 LAT set to 88 125 88 125 LEV set to 0 9995 0 9995 Time values set 2001 1 1 0 2001 1 1 0 ga set mpdraw off ga display ave tsurf t 1 t 12 Averaging dim 3 start 1 end 12 Contouring 150 to 230 interval 10 ga To produce hard copy type enable print filename gx then display the data which you require and type print when you have what you want A clear command wil
11. 40 50 60 70 80 90 100 Zonal Wind m s Meridional Wind m s Figure 2 Sample output from profile gs a profile in the Southern polar night 21 The longitude first and last latitude and local True Solar Time are supplied as arguments If the latitude range given is too small it is expanded to include several database gridpoints otherwise profile gs could be used The longitude should be given in degrees East and the time in hours 00 24 This script must be edited to select a dust scenario and season and to change the title accordingly GrADS should be run in portrait mode zonal tuv gs Plots the zonal mean and diurnal time mean temperature zonal and meridional velocity for one season in a In c latitude coordinate system GrADS should be run in portrait mode for this script Sample output from this script is given in Figure 3 zonal sdtuv gs Plots the zonal mean standard deviation of temperature zonal and meridional velocity for one season GrADS should be run in portrait mode for this script GrADS is a popular and powerful public domain software package for displaying meteorological variables You are referred to the manual for a description of all the features available Also note that as GrADS is widely used there may be scripts already written to perform the particular task you are undertaking It may be worth a search of the Internet and related newsgroups for GrADS scripts The World Wide Web page at http grads iges
12. ADS from drawing outlines of countries on the Earth although the scripts here will all do this explicitly when necessary this could be achieved with a command aliased tograds pc set mpdraw off which would run GrADS in portrait mode with no map outlines The scripts which are provided in the mcd grads subdirectory are briefly de scribed below The scripts have been commented and they should provide a useful starting point anim tsurf gs A simple animation of the diurnal cycle of surface tempera ture means during one season Useful for a quick check that the data have been read correctly a warm region local afternoon should be seen to propagate from East to West across the map map ps gs Plots maps of the diurnal mean surface pressure and its non diurnal standard deviation GrADS should be run in portrait mode for this script map windt gs Plots maps of the diurnal mean near surface wind and surface temperature GrADS should be run in portrait mode for this script profile gs This script gives the mean and confidence limits at a chosen number of standard deviations for surface variables and also plots the vertical profile of three dimensional variables from the Mars Climate Database It is important to note that the standard deviation merely represents the variability between profiles at that location and the same local True Solar Time of day dur ing that season It does not include any diurnal variability this is r
13. MARS CLIMATE DATABASE v3 0 USER MANUAL ESTEC Contract 11369 95 NL JG S R Lewis M Collins AOPP and F Forget LMD April 2001 Abstract This documentis the User Manual for version 3 0 of the Mars Climate Database MCD a database of atmospheric statistics compiled from General Circulation Model GCM numerical simulations of the Martian atmosphere This document replaces previous documents which described version 2 3 2 0 and 1 0 Version 3 0 is a major update to the database compiled from a new version of the LMD AOPP General circulation model Compared to previous versions 1 it covers a wider range of altitude from 0 to 120 km with 32 layers in the vertical 2 it uses improved topography and thermal inertia surface maps from Mars Global Surveyor 3 it includes a new dust scenario to describe the distribution of air borne dust in the atmosphere based on recent observations from Mars Global Surveyor 4 it provides radiative fluxes at the surface and at the top of the atmo sphere The software and subroutines used to access the database are similar to the V2 3 subroutines with a few improvements also outlined in this document For descriptions of the contents and structure of files details of the dust distribu tion scenarios and descriptions of the variability models see the Detailed Design Document Lewis et al 2001b and the published article entitled A Climate Database for Mars by Lewis et al 1999 More detai
14. aining the MGS and dust storms scenarios CD ROM 2 includes a directory data containing the Viking relatively dusty and low dust scenarios To have a complete database the entire contents of each directory data on CD ROM 1 and CD ROM 2 could be copied to the same place on hard disk see 4 2 drs This contains the DRS library with some documentation used to read the database files See sections 4 1 and 4 2 The file structure of the data directory is discussed in the Detailed Design Docu ment for the MCD Lewis et al 2001b Tables which show the variables available are reproduced here for convenience mean data files me contain 12 seasonal mean values corresponding to 12 Solar times of day for the variables shown in Table 1 and standard deviation data files sd contain seasonal standard deviation values of the variables in Table 2 4 Installation 4 1 Software Requirements e The MCD is primarily designed to operate in the UNIX environment on a work station Access software is written in FORTRANTT for which a compiler is needed EDorib CO ice cover co2ice kg m Surface emissivity emis none Surface temperature tsurf K Surface pressure ps Pa LW thermal IR radiative flux to surface fluxsurflw W m SW solar radiative flux to surface fluxsurf_sw W m 2 LW thermal IR radiative flux to space fluxtop w W m SW solar radiative flux to space fluxtop sw Atmospheric temperature K Zonal East West
15. ase for Mars by Lewis et al 1999 This document provides the user of the MCD with a description of how to access the data in the database Descriptions of the models and of the validation procedure are available in other documents relating to the project The MCD can also be accessed in a variety of data formats using the World Wide Webathttp www lmd jussieu fr mars html 2 Differences Between Version 3 0 and Previous Versions of the MCD e The main difference between version 3 0 and 2 3 are mostly related to the con tent of the database files due in particular to improvements made in the models The general circulation models used to compile the database run with a higher resolution of 3 75 x 3 75 For simplicity and to reduce the size of the database the data were stored on 5 x 5 grid used to compile the database 1 The models and the derived database cover a greater range of altitude from 0 to 120 km with 32 layers in the vertical 2 The models use improved surface properties data from the Mars Global Surveyor spacecraft including the accurate topography from the Mars Ob server Laser Altimeter and the new thermal inertia map from the Thermal Emission Spectrometer 3 The database includes a more realistic dust scenario to describe the dis tribution of airborne dust in the atmosphere based on recent observations from Mars Global Surveyor 4 The database now includes solar and thermal infrared radiative flu
16. at it is not possible for GrADS to display data on a true height co ordinate without writing external routines to read the entire database convert to height coordinates by integrating the hydrostatic equation for each profile add the height of the local surface above the geoid interpolate onto a uniform height coordinate grid and then re write the database and control files in this new form This process is per fectly feasible using the FORTRAN routines supplied with the MCD but requires disk space to store the new data and results in losing nearly all the high vertical resolution near surface information For simple data visualization this is not worthwhile and the data can be looked at on sigma surface In practice two kinds of grads ct 1 files are provided The ones of the form name ct1 will yield graphic on 0 p ps surface with c varying from 1 surface to near 0 upper layer The ones of the form name a ctl access the same data but provide a pseudo height vertical coordinate instead of sigma which may be more convenient for quick plotting very roughly for Mars z 101n c km and so a In o axis is adequate for most plots Note that the pseudo height is based on a 10 km scale height and is particularly inaccurate in the upper atmosphere See table of layers in Detailed Design Document The fortran access software calculates height more accurately by integrating the hydrostatic equation If accurate height is a priorit
17. ation for surface pressure e Large scale perturbations due to the motion of baroclinic weather systems These perturbations are correlated in longitude and altitude e Perturbation equal to n times the standard deviations for all the variables 10 A comprehensive explanation of the perturbations is included in the Detailed De sign Document 5 22 How to use atmemcd subroutine A Programmer s Guide is available for those who wish to include the atmemcd subroutine in their program Forget et al 20012 A simple program using the atmemcd subroutine named test emcd is provided in the emcd directory The program first has to be compiled The Unix command make can be used gt make test emcd test emcd Then just answer the questions Inthe emcd test case sub directory a tool to test that atmemcd is running ac curately on your computer using test emcd is provided Please read emcd testcase README for further information To compile your own program you can use make like for test emcd by adapt ing the file makefile just mimic what is done for test emcd 5 3 MCDGM the MarsGRAM Style Interface 5 3 1 Interactive Mode Given the widespread use of MarsGRAM in the community a MarsGRAM style inter face is supplied with the MCD The software for this is contained in the emcd directory and the main program is called mcdgm It now uses the atmemcd subroutine The program first has to be compiled The Unix
18. command make can be used make mcdgm The MCDGM interface performs in a very similar way to MarsGRAM version 3 5 with regards to input and output and is self explanatory in its usage A sample interactive session is shown here mcdgm 11 Mars Climate Database Version 3 0 Enter Enter list Enter and maximum number of positions all integers numbe fil e name fil e name r ol month day of f posit 7 20 1976 4 for EOL ions tabulated output to read positions MarsGRAM month 4 digit year style interface full output listing CON for screen listing from TRAJDATA Enter zero file Enter initial GMT Time in Hours Minutes Seconds all integers 12 50 00 Date 7 20 1976 Julian Date 2442980 0 GMT Time 12 50 0 0 Ls 98 9 degrees for this date Select dust scenario 1 MGS dust scenario 2 Viking dust scenario 3 Low dust scenario 4 Dust storm tau 2 5 Dust storm tau 5 1 Enter perturbation model 1 none 2 large scale 3 small scale 4 large scale and small scale 1 Enter seed teger lt 30 000 1 Select x cod Code and y code P for random number generator arameter any positive in for plotable output versus desired parameter s ceo 10 01 5 CO Po S m m Longit Time Time Areocentric Hour Angle Height Height above local
19. distribution before they are used this permits use of implicit noneinroutines which make use of DRS a header file drsdeclare h has been added in emca to do this 5 Accessing Data 5 1 Choosing a Method of Database Access There are four main ways of accessing data from the MCD which have been imple mented to date Firstly if you know FORTRAN the best way to retrieve environmental data from the Mars climate database at any given locations and times is to use the subroutine mode of the software supplied with the Mars Climate Database In practice one only has to call a main subroutine named atmemcd from within any program written in FORTRAN A simple example of such a program test emcd which can be easily modified is provided This mode was developped with a particular attention to trajec tory simulation application but It should also be used for other purpose A atmemcd programmer s guide is available in a separate document Secondly an interface MCDGM is supplied with the Mars Climate Database as a set of FORTRAN source code in the emcd The MCDGM interface performs in a very similar way to MarsGRAM version 3 5 It is intended to make the database as easy to use as possible for those with prior experience of MarsGRAM as well as providing possible access for all users to the complete database It can be run in interactive or batch mode Thirdly it is possible to access the database directly from within any program written
20. epresented in the twelve means contained in the mean data file for different times of day nor any small scale variability nor any information about correlation and scales of variability within or between individual profiles the last two points are ad dressed by the main database software The longitude latitude and local True Solar Time are supplied as arguments The longitude should be given in degrees East and the time in hours 00 24 This script must be edited to select a dust scenario and season and to change the title accordingly A metafile named using the plot parameters is written profile lon lat hr where lon is the longitude lat the latitude and hr the local time selected which can then be viewed with gxt ran or converted to postscript for printing with gxps or gxeps GrADS should be run in portrait mode Sample output from the profile gs script is shown in Figure 1 for summer afternoon profiles near the Viking Lander 1 site and for contrast Figure 2 shows night time profiles in a winter polar region at the same time of year section lat gs This script is similar to profile gs except that a range of latitudes can be given to produce a sigma latitude section through the database 19 gx MCD MGS dust Ls 90 120 Profile location lon 48 Mean data with confidence limits at 1 Surface Pressure Pa 686 16hrs standard deviation lat 22 local time 710 734 Surface Temperature K
21. f density Percentage density standard deviation Large scale density perturbation Small scale gravity wave density perturbation East West zonal wind Density scale height North South meridional wind Pressure Mean ground temperature Mean atmospheric temperature Maximum ground temperature Minimum ground temperature Tabulated output see text Table 3 Output files produced by the MCDGM interface software Density perturbation 9 5 0 03 of mean value Eastward Wind 18 3 m s Northward Wind 4 0 m s Time rel to TO O O sec 0 000 sols Ls 98 Height 30 00 km 33 45 km Scale Hgt H p 7 92 H rho Latitude 22 000 degrees West Longitude 48 000 degr Sun Latitude 25 00 deg Mars Orbital Radius 1 640 AU Sun Longitude 111 31 deg Local Time 16 22 Mars hours Temperature 154 1 K Pressure 2 100E 01 N m 2 Density Low Avg High 6 785E 04 7 064E 04 7 342E 04 kg m 3 Departure COSPAR NH Mean 30 8 5 27 9 Al Density perturbation 0 48 of mean value Eastward Wind 24 3 m s Northward Wind 7 6 m s In addition to the output shown above which may be directed to the console or a file the data files shown in Table 3 are produced holding the data indicated tabulated against a user specified coordinate Data are presented in SI units unless otherwise stated The user specified 1ist file contains tabulated output in a column wise basis of the foll
22. ironment and Society World Wide Web server at http grads iges org grads Installing the MCD from the CD roms Create a working directory mcd on a disk where you wish to use the database Copy the following directory from the CD rom to this location at least emcd and if you need them drs grads and docs If possible you should copy the data from the CD ROM to hard disk The data can be accessed direct from the CD ROMS see below but this last solutions is slower and less convenient We suggest that you copy the directory data from CD ROM 1 to the working directory mcd for instance or to another disk if there are not enough disk space available there see how to link datafiles and software below To have a complete database the entire contents of the di rectory data on CD ROM 2 should then be copied to the same place as the other files which were in the directory data which was on CD ROM 1 A full installation of the MCD takes about 1 Gb of disk space The amount of disk space needed could be reduced further by only retaining a limited range of dust scenarios or seasons of interest within the dat a subdirectory In the working directory e g mcd it is recommended to set up a EMCD_DATA symbolic link in the same directory to point to the data directory wherever it has been stored ln s full path to mcd data EMCD DATA For instance if one want to access the data direct from the CD ROMs ensure that the correct
23. l start a new page and disable print or quit at the end of the session closes the ilename gx file The gx file can be viewed again on the screen with the gxt ran utility or converted to PostScript for printing with gxps or gxeps These utilities and instructions for using them are provided with the GrADS distribution whether you get gxps gxeps or other programs with similar names depends on exactly which version of GrADS you obtain For more complicated output or for repeated applications which can be run in batch mode it is more convenient to write a GrADS script Some are provided in the mcd grads subdirectory it might be necessary to change the path to the data files to where the mcd directory has been installed on your machine if these scripts are to be run from another directory The final part of the filename determines the dust scenario and season according to the code described previously in this document These can be changed and the titles modified accordingly by editing the scripts If different quantities are required from those which they plot it should be straightforward to write new scripts using the ones supplied as templates Most of the scripts are intended to produce output in portrait orientation so either run GrADS and answer no to the initial landscape mode question or specify portrait mode from the command line grads 18 p It is also useful to run the GrADS command set mpdraw off which prevents Gr
24. led information on the main access subroutine atmemcd can be found in the related Programmer s Guide Contents 1 Introduction 2 Differences Between Version 3 0 and Previous Versions of the MCD 3 Contents of the Mars Climate database 4 Installation 4 1 Software Requirements leen 4 2 Installing the MCD from the CD roms 5 Accessing Data 5 1 Choosing a Method of Database Access 5 2 Using the atmemcd subroutine 5 2 1 Whatis atmemcd subroutine 5 2 2 Howto use atmemcd subroutine 5 3 MCDGM the MarsGRAM Style Interface 5 3 1 Interactive Mode llle 5 32 Output Produced oouo 5 33 Running the MCDGM in Batch Mode 5 4 Using the DRS Library leen 5 4 1 Opening and Closing Files 5 4 2 Manipulating Data aaaea 5 5 USME GADS o eai ai a v Sob n a USE eV 6 References 10 10 11 11 11 13 15 16 16 17 17 22 1 Introduction The Mars Climate Database MCD is a database of atmospheric statistics compiled from state of the art General Circulation Model GCM simulations of the Martian at mosphere Forget et al 1999 The models used to compile the statistics have been extensively validated using available observational data and represent the current best knowledge of the state of the Martian atmosphere given the
25. org grads isa good starting place 6 References Collins M and Lewis S R 1997a Mars Climate Database v1 0 User Manual Eu ropean Space Agency Technical Report Collins M and Lewis S R 1997b Mars Climate Database v1 0 Detailed Design Document European Space Agency Technical Report Collins M Lewis S R Read P L Thomas N P J Talagrand O Forget E Fournier R Hourdin F and Huot J P 1996 A climate database for the Martian atmo sphere in Environment Modelling for Space based Applications European Space Agency SP 392 323 327 Forget F Hourdin F Fournier R Hourdin C Talagrand O Collins M Lewis S R Read P L and Huot J P 1999 Improved general circulation models of the Martian atmosphere from the surface to above 80 km J Geophys Res 104 24 155 24 176 Forget F C Hourtolle and Lewis S R 2001a Mars Climate Database atmemcd subroutine prgrammer s guide 22 MCD MGS dust Ls 2 0 3500 110 100 100 yo KE Jen D XL O O D ep CX 210 JON yw A Jen D XL o Oo D op em en CZ i5 x Oo Oo 2 D 09 As EQ 30N 60N Zonal Diurnal Mean Meridional Wind m s Figure 3 Sample output from zonal tuv gs 23 Hourtolle C Forget F and Lewis S R 2001b Mars Climate Database atmemcd subroutine programmer s reference Justus C G Alyea
26. owing variables time height latitude longitude density temperature zonal wind meridional wind percentage density standard deviation small scale gravity wave density perturbation and L 14 9 deg 7 92 km ees 9 5 5 3 3 Running the MCDGM in Batch Mode Alternatively the user can run the MCDGM interface in batch mode using a simple Unix script This script could be executed as a background job or at a later time using some batch queueing software Script to run the Mars Climate Database MarsGRAM style inter face mcdgm set workdir YOUR WORK DIRECTORY set mcddir FULL PATH NAME mcd cd Sworkdir cat gt mcdgm in lt lt eof_mcdgm in vil ent list vil ent out 7 20 1976 100 12 50 00 22 48 1 21 dis 0 m 0 eof_mcdgm in Smcddir mcdgm lt mcdgm in gt mcdgm out 15 5 4 Using the DRS Library Data in the MCD are written in DRS format If you are not using a package such as GrADS which can read DRS format you can write a program in FORTRAN or some other language such as C or IDL to access the data using the DRS library Some general documentation on DRS is available in directory drs doc Within the at memcd F or mcdgm F source files we also supply several FORTRAN subroutines For most applications using the atmemcd subroutine should be good enough to ac cess the database but if you want to process to the global fields it may some
27. terrain Latitude tude d from st Use y code 0 2 0 Enter 1 for 0 Enter 22 48 0 initial from st abov de referenc llipsoid km g eg art Earth seconds art Martian Sols Longitude of Sun for normal log base 10 or 2 Surface elevation MKS units c 9 for dii h Fh latitude and west longi 3 446668 km at 12 km Ls deg for Local Time Mars hours 15 or density ference from COSPAR tude in degrees this location for plotable output vs x code variable only Enter Initial Height relative to zero datum km 3 446668 Enter Increments in Height km Latitude deg West Longitude deg and Time sec 10 00 Os 5 3 2 Output Produced The above example produces the following output at the console Viking Lander 1 entry profile The user can first try this example to check that the MCDGM interface has been installed correctly There will of course be differences in the data values output if another dataset or any of the variability models are used Time rel to TO 0 0 sec 0 000 sols Ls 98 9 deg Height 0 00 km 3 45 km Scale Hgt H p 11 23 H rho 11 23 km Latitude 22 000 degrees West Longitude 48 000 degrees Sun Latitude 25 00 deg Mars Orbital Radius 1 640 AU Sun Longitude
28. time be easier to use DRS 5 4 1 Opening and Closing Files To access the data you must first open the file An example of opening an MCD file within a FORTRAN program is shown here include drsdef h integer udrs DRS file unit number integer ierr character 256 datfile DRS data file character 256 dicfile DRS dictionary file udrs 60 datfile FULL PATH NAME mcd data viks0O4me dat dicfile FULL PATH NAME mcd data viks04me dic ierr aslun udrs dicfile udrs 1 datfile IDRS_READ read some DRS data ierr cllun udrs close the file again 16 5 4 2 Manipulating Data Once the file has been opened you can read data from the MCD either by using the DRS routines directly or by using subroutines from the emcd directory The following routines may prove particularly useful They can be found in the main atmemcd F file Each subroutine is commented within the code to indicate the type and size of arguments which it expects note that in some cases the number of arguments has changed since earlier versions of the MCD On request a detailed description of the subroutines can be provided in a Programmer s Reference Document e loadvar must be called first to load the needed database arrays e var2dretrieve one value of a 2 D field at a given location and time Uses bilin ear interpolation to translate the database fields to the user specified longitude latitude and time e var3d Retrieve
29. xes at the surface and at the top of the atmosphere 5 The horizontal resolution of the database has changed to 5 x 5 e The main difference between version 2 3 and 2 0 was the use of the main subrou tine ATMEMCD which computes meteorological variables from Mars Climate Database MCD This new subroutine has been especially designed for atmo spheric trajectory computation and is useful for other purposes The principal difference between version 2 0 and 1 0 of the MCD was that the large scale variability model now makes use of two dimensional multivari ate Empirical Orthogonal Functions EOFs which describe correlations in the model variability as a function of both height and longitude rather than solely of height as in version 1 0 These are described in the Detailed Design Docu ment which accompanies this report The 2 D EOFs allow realistic variability to be modelled for trajectories which span a range of longitudes As in version 1 0 EOFs are stored for a range of latitude bands but instead of retaining 6 1 D EOFs at each horizontal location for each of 12 seasons now 72 2 D EOFs are stored for each latitude band and their amplitude is modelled by a set of princi pal components tabulated once per day 669 times throughout the model Mars year This procedure is no more costly to the end user in terms of either disk storage or CPU time but gives a much improved description of the variability as a function of both space and time
30. y then access to the database should be made through either of the first two methods Nevertheless GrADS is recom mended as a way of producing reasonable quality graphical output quickly and is ideal for examining one two or three dimensional slices through the data 5 2 Using the atmemcd subroutine 5 2 1 What is atmemcd subroutine The subroutine atmemcd is contained in the emcd directory The Fortran subroutine ATMEMCD allows computation of the following basic meteorological variables useful in particular for atmospheric trajectory calculations e pressure e temperature e density e zonal and meridional wind velocity e Mean shortwave solar and longwave thermal IR radiative fluxes at surface and at the top of the atmosphere The values are dependent of the location defined by its altitude latitude and East longitude of the time defined by Earth date or Mars date as well as the chosen dust scenario Above the top level of the database density and pressure are estimated by integration of the hydrostatic equation assuming a prescribed temperature profile see programmer s guide For these variables the subroutine delivers mean values and if requested adds different kind of perturbation to these mean values except for the radiative fluxes The available perturbation kinds are e Small scale perturbations due to the upward propagation of gravity waves for any altitudes there are no small scale perturb
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