MARS CLIMATE DATABASE v5.0 USER MANUAL
Contents
1. Create a working directory e g mars on a disk where you wish to use the database Extract untar the contents of the MCD distribution there 3 With the installation of the minimal baseline MCD distribution only the climatology dust scenario with an average Extreme UV solar input is provided corresponding datafiles are in the clim_aveEUV subdirectory of the data directory The other dust scenarios clim_minEUV climmaxEUV cold warm strm are provided separatly and should likewise be added as subdirectories in the data directory A full installation all 8 scenarios of the MCD takes about 8 5 Gb of disk space 4 In the working directory e g mars it is convenient to set up a MCD_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 MCD_DATA N B In the cal1_mcd subroutine the path to the directory can be given as an input using the dset argument e g dset full path to mcd data although by default the subroutine will use MCD_DATA if dset is not initialized or setto 5 If NetCDF is not available on your system you must install the NetCDF library following the instructions given on their www site see above For this purpose you have the choice either to build and install the NetCDF package from source or use prebuilt binary releases if they are available for your platform check the Frequently Asked Question2. m e extvar 3 Altitude above local surface m extvar 4 Orographic height m altitude of the surface with respect to the areoid N B Depending on the value of input flag hireskey references to altitudes and orographic height are with respect to GCM grid or high resolution MOLA topography and areoid extvar 5 Ls solar longitude of Mars deg extvar 6 LTST Local True Solar Time at longitude lon in martian hours 1 24 of a mars day extvar 7 Universal solar time LTST at 1on 0 hrs extvar 8 Cp Air specific heat capacity J kg K7 extvar 9 y C p Cv Ratio of specific heats extvar 10 RMS day to day variations of density kg m N B The given RMS is either pressure wise if zkey 4 or altitude wise if zkey 1 2 or 3 14 Table 2 CALL_MCD output arguments continued e extvar 11 Not used set to zero e extvar 12 Not used set to zero e extvar 13 Scale height H m at given input altitude xz e extvar 14 GCM orography m will be equal to extvar 4 if input parameter hireskey 0 N B Provided for specialist interested in the differences between low resolution i e the GCM resolution and high resolution MOLA to pography e extvar 15 Surface temperature K e extvar 16 Daily maximum mean surface temperature K e extvar 17 Daily minimum mean surface temperature K e extvar 18 Surface temperature RMS day to day varia tions K e extva
3. Ideally you can install the full NetCDF package as recommanded on the web site In practice the minimum you need to run the access software are only two files an include file named netcdf inc and a Fortran library file named Libnetcdf a The version of the files depends of the machine and of the compiler An easy way to get them is to go to the unidata netcdf web page click on precompiled binaries download a compressed file corresponding to your operating system uncompress the file You ll find the netcdf inc in the include directory and the Libnetcdf a in the lib directory You ll need to provide the path to these two files when compiling applications see the compile files in the database Un fortunately this does not always work if your compiler doesn t work with the precompiled library you will have to recompile Netcdf with it and follow the web site instructions 4 Ways to access the database There are three main ways of accessing data from the MCD which have been implemented to date Firstly if you know Fortran the best way to retrieve environmental data from the Mars cli mate 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 call_mcd from within any program written in Fortran A simple example of such a program test_mcd F which can be easily modified is provided This mode was developed
4. are in this directory Indi vidual dust scenarios datafiles are in corresponding subdirectories clim_aveEUV for the baseline climatology dust scenario with average Extreme UV EUV input clim_minEUV for the baseline climatology dust scenario with minimum EUV input clim_maxEUV for the baseline climatology dust scenario with maximum EUV input cold for the cold scenario warm for the warm scenario and st rm for the dust storm scenarios 3 Installation 3 1 3 2 1 2 Software Requirements The MCD is primarily designed to operate in the Unix Linux environment on a PC or a workstation Access software is written in Fortran and uses some Fortran90 extentions and intrinsics for which a Fortran compiler is needed Because the NetCDF libraries see below are also available under Windows systems several users have succefully compiled and used the access software as under Unix Linux Never theless it has not been fully tested by our team but we can confirm that it compiles fine under the Cygwin environment on Windows using the GNU gfortran compiler The data in the MCD is written as Network Common Data Form NetCDF files The NetCDF library is freely available from the Unidata web site http www unidata ucar edu software netcdf NetCDF works on most current operating systems including AIX HPUX IRIX Linux MacOS X OSFI SunOS 4 Solaris Sparc and i386 MS Windows Installing the MCD
5. means here that contrary to the usual IDL convention meanvarz and extvarz left index is only used starting at 1 to keep the same numbering than in the Fortran code and thus follow the call_mcd subroutine outputs given in section 5 4 How to use it 1 Copy you may also just use symbolic links files constants_mcd inc call_mcd and heights F from parent dircetory mcd to the current directory 2 Edit the the Fortran code mcd_id1 F which is used by IDL to call call_mcd and gt When multidimensinal data is sought dimensions are arranged as follows meanvarz 6 nlat nlon nz nLs nloctime 22 set the path the dset variable to the MCD data directory 3 Compile the Fortran code mcd_id1 F You may use the script compile _mcd_idl after having edited it to match your needs 4 Call mcd_idl pro from IDL using your favorite method File test _idl pro is provided as an example of an IDL program which uses mcd_idl pro e profils_mcd_idl pro is an IDL procedure that can be used to retrieve atmospheric profiles for a list of horizontal coordinates and times This is especially useful to emulate observations of atmospheric profiles from an instrument inputs Solar longitude Ls in degrees Local time Loct in martian hours latitude lat degrees north east longitude lon degrees dust scenario dust from 1 to 8 vertical coordinate type zkey 1 2 3 or 4 high resolution mode hireskey on 1 off 0 and vertical coordinate
6. eek ee a ed RWW Ww 6 Calling the CALL_MCD subroutine from IDL 7 Calling the CALL_MCD subroutine from Matlab 8 Calling the CALL_MCD subroutine from Scilab 9 Calling the CALL MCD subroutine from C or C programs 10 Calling the CALL_MCD subroutine from python 11 High accuracy surface pressure tool preso III Howto usepresO oe ee ee a a ee 11 2 Input output of subroutine presO 22 000 4 12 The heights tool 12 1 Arguments of heights subroutine 0 A Differences Between Version 5 0 and Previous Versions of the MCD 5 3 Compiling and running CALL_MCD 4 5 4 CALL_MCD input and output arguments 0 5 5 The right use of the CALL_MCD subroutine 0 5 5 1 Perturbed atmospheres 2 04 4 5 5 2 Runningtime 0 2 00002 00004 22 23 23 24 24 24 25 25 25 26 27 1 Introduction The Mars Climate Database MCD is a database of atmospheric statistics compiled from state of the art Global Climate Model GCM simulations of the Martian atmosphere The GCM computes in 3D the atmospheric circulation and climate taking into account radiative transfer through the gaseous atmospheres and the dust and ice aerosols includes a representation of the CO ice condensation and sublimation on the ground and in the atmosphere simulates the water cycle with modelling of cloud microphysics the dust multisize particle transport t
7. of the database For the last type of perturbation i e times the standard deviation the standard deviation is interpolated from the day to day RMS variabilities stored in the database If the user works with pressure as the vertical coordinate then the added variabilities are pressure wise and altitude wise otherwise Above the top level of the database the standard deviation represents a constant percentage of the mean value this percentage is equal to those at the top of the database The compile file which contains an example of the Unix command line to compile the subroutine and program The file test _mcd def contains a list of input data for test_mcd see section 5 3 A subdirectory test case containing test cases used to test the accuracy of your installation of the database the julian F file which contains a subroutine which computes the Julian date correspond ing to a given calendar date the heights F file which contains the subroutines necessary to convert distances expressed as distance to planet center height above areoid and height above local surface Given any of these this routine computes the other two either at GCM grid resolution or using high 1 32 degree resolution see section 12 call_mcd does these conversions using these routines so users need not use it These routines are nonetheless kept seperate from the main file call_mcd F for specialists who might want to use it seperately subdirectory pre
8. the program 6 Calling the CALL_MCD subroutine from IDL The Interactive Data Language IDL is a commercial software for data analysis and visualization tool that is widely used in earth planetary science and astronomy The mcd id1 subdirectory contains two tools which show how the call_mcd subroutine may be called from IDL Note that call_mcd is not directly called from IDL as such auxiliary Fortran programs are used These programs are launched from the IDL session and their output written to an intermediate file is then loaded and used e mcd _idl pro is an IDL procedure that can be used to retrieve a block of atmospheric data from the Mars Climate database inputs Solar longitude Ls in degrees Local time Loct in martian hours latitude lat degrees north east longitude lon degrees dust scenario dust from 1 to 8 vertical coordinate type zkey 1 2 3 or 4 high resolution mode hireskey on 1 off 0 and ver tical coordinate xz altitude m or pressure level Pa All the time and space coordinate can be IDL arrays For instance if you want to make a map of temperature at a given local time altitude and Ls then in input lat and lon should be arrays outputs meanvarz and extvarz as defined for call_mcd except that they are multidimensional arrays depending on the dimension of the inputs For instance in our example of a map the IDL dimension of meanvarz will be DBLARR 5 1 nlat nlon gt 5 1
9. variability as a function of both height and longitude rather than solely of height as in version 1 0 29
10. with partic ular attention to trajectory simulation applications but it can also be used for most other purposes Further information on the use of call_mcd are available below Secondly users who prefer using IDL Matlab or Scilab software or who program in C C and or Python will find examples of how to interface their favorite tools with the Fortran subroutine call_mcd in corresponding subdirectories see sections 6 to 10 Note that some provided exam ples are quite straightforward and brute force approaches fancier and more efficient couplings with the MCD are clearly possible Thirdly it is possible to access the database directly from within any program written in any high level language or software which can read NetCDF files This gives some flexibility for par ticular applications e g when one wants to handle global fields although it does demand a much greater understanding of how the database contents are organised see the MCD Detailed Design Document for a description as well as of how the variability models if these are required should This symbolic link strategy unfortunately does not work with Windows where the full path to the data directory must be used be used The Fortran subroutines used by the call_mcd routine included in file call_mcd F illustrate how to open and read the database files If you are interested in inspecting plotting mean and standard deviation data from the raw database datafiles
11. xz altitude m or pressure level Pa xz is the vector of altitude m or pressure Pa defining the vertical coordinates of the profiles Ls Local time lat and lon must be array of the same size providing a list of coordinate where you want to retrieve profiles outputs meanvarz and extvarz as defined for call_mcd except that they are ar rays containing the profiles for the list of horizontal and time coordinates For instance meanvarz has the following dimension DBLARR 5 1 number of profiles number of point in each profile 5 1 means here that contrary to the usual IDL convention meanvarz and extvarz left index is only used starting at 1 to keep the same numbering than in the Fortran code and thus follow the call_mcd subroutine outputs given in section 5 4 How to use it 1 Copy you may also just use symbolic links files constants_mcd inc call_mcd and heights F from parent dircetory mcd to the current directory 2 Edit the the Fortran code profils_mcd_idl F which is used by IDL to call call_mcd and set the path the dset variable to the MCD data directory 3 Compile the Fortran code profils_mcd_idl F You may use the script compile _profils_mcd_idl after having edited it to match your needs 4 Call profils_mcd_id1l pro from IDL using your favorite method the filetest_profils_idl pro is an example of an IDL program which uses profils_mcd_idl pro 7 Calling the CALL_MCD subroutine from Mat
12. CALL_MCD output arguments continued extvar 31 Thermal IR A gt 5y m flux to surface W m extvar 32 Solar flux A lt 5 um to surface W m extvar 33 Thermal IR flux to space W m extvar 34 Solar flux reflected to space W m extvar 35 Surface CO ice layer kg m extvar 36 DOD Dust column visible optical depth From local surface to the top of the atmosphere at wavelength 0 67 um extvar 37 Dust Optical Depth RMS day to day varia tions extvar 38 Dust mass mixing ratio kg kgair extvar 39 Dust effective radius m Dust size distribution is assumed to follow a log normal distribution with an effective variance of veff 0 5 Therefore the geometric mean radius ro can be derived from the effective radius reff as ro 5 2 Teff X 1 veff 0 36 X reff extvar 40 Dust deposition rate on a flat horizontal plane at the surface of Mars kg m s 17 Table 2 CALL_MCD output arguments continued e extvar 41 Water vapor column kg m N B If you prefer to have this value in precipitable microns pr um i e g m then simply multiply it by 1000 e extvar 42 Water vapor vol mixing ratio mol mol e extvar 43 Water ice column kg m e extvar 44 Water ice mixing ratio mol mol e extvar 45 Water ice effective radius m Water ice cloud particule size distribution is assumed to follow a log normal distribution with an effective variance of ves 0 1
13. MARS CLIMATE DATABASE v5 0 USER MANUAL ESTEC Contract 11369 95 NL JG Mars Climate Database and Physical Models CNES Contract Base de donn es climatique martienne E Millour F Forget LMD Paris S R Lewis The Open University Milton Keynes December 2012 Abstract This document is the User Manual for version 5 0 of the Mars Climate Database MCD de veloped by LMD Paris AOPP Oxford Dept Physics amp Astronomy The Open University and IAA Granada with the support of the European Space Agency and the Centre National d Etudes Spatiales This is a database of atmospheric statistics compiled from Global Climate Model GCM numerical simulations of the Martian atmosphere This document replaces pre vious documents which described versions 4 x 3 2 and 1 and includes a thorough description of the access software provided to extract and postprocess data from the database The database extends up to about 250 km in altitude in addition to statistics on tempera ture wind pressure radiative fluxes it provides data such as atmospheric composition includ ing dust water vapor and ice content and make use of dust and Extreme UltraViolet EUV scenarios to represent the variation of dust in the atmosphere and solar EUV conditions Lin ear interpolation in time of datafiles data is used to reconstruct variables at user specified time of day and solar longitude and various kind of vertical coordinates
14. There fore the geometric mean radius ro can be derived from the effective 5 2 radius reff as ro Treff X 1 vesp 0 8 X reff e extvar 46 Convective planetary boundary layer PBL height m e extvar 47 Maximum upward convective wind m s within the planetary boundary layer PBL e extvar 48 Maximum downward convective wind m s within the planetary boundary layer PBL e extvar 49 Convective vertical wind variance m s at input altitude xz This quantity has only a meaning inside the PBL it is set to zero if the sought input xz altitude is above the PBL e extvar 50 Convective eddy vertical heat flux m s K7 at input altitude xz This quantity has only a meaning inside the PBL it is set to zero if the sought input xz altitude is above the PBL e extvar 51 Suface wind stress kg m s e extvar 52 Surface sensible heat flux W m Negative when the flux is from the surface to the atmosphere e extvar 53 R Reduced molecular gas constant J kg K of the atmosphere at input altitude xz e extvar 54 Air viscosity v estimation N s m7 e extvar 55 Not used set to zero e extvar 56 Not used set to zero e extvar 57 CO volume mixing ratio mol mol e extvar 58 N volume mixing ratio mol mol e extvar 59 Ar volume mixing ratio mol molair e extvar 60 CO volume mixing ratio mol mol 18 Table 2 CALL_MCD output arguments cont
15. ario low dust conditions solar min N B The solar conditions describe variations in the Extreme UV input which control the heating of the atmosphere above 120 km which typically varies on a 11 years cycle The different dust scenarios differ by dust amount and distribution used to create the data files dust is highly variable on Mars from year to year The Climatology dust scenario is designed be representative of a baseline typical Mars year The warm and cold scenario are provided to bracket the possible dust con tent of the atmosphere outside global dust storms dust storm 7 5 represents Mars during a global dust storm dust opacity set to 5 and using a darker dust Only available when such storms are likely to happen during northern fall and winter Ls 180 360 Please check the Detailed Design Document for further information 12 Table 1 CALL_MCD Input arguments continued perturkey integer Flag to set the type of perturbation to add 1 None 2 Add large scale perturbations using EOFs 3 Add small scale perturbations gravity waves 4 Add small and large scale perturbations 5 Add seedin times the standard deviation N B For the small scale or large scale perturbations a seed for the random number generator must be specified see seedin argument When large scale perturbation is requested as long as seedin remains the same no new random vector is generated and you work with the sa
16. de global dust storms which are thought to be highly variable locally and from year to year Overall this leads to a total of 8 different available scenarios since there are 3 EUV cases for Climatology and dust storm scenarios The user is referred to the Detailed Design Document for further information 1 3 High resolution mode The Mars Climate Database has been compiled from the output of a general circulation model in which the topography is very smoothed because of its low resolution In addition the pressure varia tions due to the CO2 cycle condensation of atmospheric CO2 in the polar caps that is computed by the model is only based on the simulation of the actual physical processes The polar cap physical properties have been tuned to somewhat reproduce the observations but no correction was added As of version 4 2 access software includes a high resolution mode which combines high resolution 32 pixels degree MOLA topography and the smoothed Viking Lander 1 pressure records used as a reference to correct the atmospheric mass with the MCD surface pressure in order to compute surface pressure as accurately as possible The latter is then used to reconstruct vertical pressure levels and hence within the restrictions of the procedure yield high resolution values of atmospheric variables The procedure by which high accuracy surface pressure is computed is also implemented as a light and autonomous tool preso see s
17. e of the surface m at given space coordinates ierr integer control variable 0 if all is ok 12 The heights tool The call_mcd routine handles and converts various types of vertical coordinates as explained in section 5 4 Users interested in having a light and fast tool for converting vertical coordinates expressed as distance to the center of the planet height above the areoid zero datum and height above the local surface may use the heights subroutine Given any of the three this routine computes the other two The only files that presO requires are VL1 1s mola32 nc and ps_clim nc Users interested in installing only presO and not the whole database should copy these files which are in the data directory to a local directory We recomend using the same symbolic link stategy as given in section 3 2 25 Just as call_mcd heights can work in high resolution i e using high resolution 32 pix els degree MOLA topography and areoid or low resolution i e at GCM horizontal grid res olution of 5 625 x 3 75 mode At GCM resolution topography and areoid are read from the mountain nc datafile At high resolution the MOLA topography file mola32 nc and spher ical harmonics expansion coefficients in file mgm1025 are used All these files are stored in the data directory of the MCD distribution 12 1 Arguments of heights subroutine A Fortran call to the heights subroutine should be as follows call heights d
18. e perturbations are calculated as follow The gravity wave perturbation of a meteorological variable is calculated by considering vertical displacements of the form ee on 60 1 where is a characteristic vertical wavelength for the gravity wave and o is a randomly generated surface phase angle surface angle z is the amplitude of the wave depending on the height z dh is the sub grid scale surface roughness the variability on scales smaller than the explicit database resolution and is a function of location on the Martian surface If z is higher than 100 km the amplitude of the wave is taken to be equal to the amplitude at 100 km The amplitude of the wave is limited to 2 7 to saturate the amplitude of the perturbation when it becomes statically unstable The large scale perturbation in the Mars Climate Database is represented using a technique that is widely used in meteorological data analysis namely Empirical Orthogonal Function EOF analysis A two dimensional multivariate EOF of the main atmospheric variables surface pressure atmospheric temperature and wind components is used which describes correlations in the model variability as a function of both height and longitude 200 EOFs have been retained in the series in order to reproduce the variability of the original fields Above the top level of the database the perturbation represents a constant percentage of the mean value this percentage is equal to those at the top
19. e scale perturbation scheme are now at higher resolution 32 x24 twice what was used previously Moreover for the climatology scenario EOFs corresponding to the individual Mars Years 24 26 27 29 and 30 runs are used Many new variables have been included Columns and volume mixing ratios of Ar O 02 H H2 electrons key parameters concerning the convective planetary boundary layer PBL etc Users may now pick which extra variables need be computed and outputed rather than the all or nothing capability of previous MCD software Differences between version 4 3 and version 4 2 e The main upgrade in MCD version 4 3 is the improvement of the large scale perturbation model Version 4 3 thus uses the same database datafiles as version 4 2 except for a subset which contains updated data required for the large scale perturbation model e Other changes that have been introduced are An additional vertical coordinate zkey parameter may be used to specify vertical coordinate as altitude above reference radius arbitrarily set to 3 39610 m The output unit to which messages are written is now a parameter that can be set by the user the default output unit is set to 6 which implies in conformance with Fortran standards the standard output In order for the whole MCD to fit in a single DVD some datafiles all those which con tain data about dust storm sceanarios i e files in the dat a di
20. e small or large scale perturbations which take into account some correlation of perturbations in the space and between variables Then when you use the perturkey 5 perturbation you have to keep the same seedin ie multiplying factor along the whole trajectory to avoid introducing unrealistic gradients between consecutive values When generating a randomly perturbed atmosphere using the large scale perturbations perturkey 2 or 4 to simulate a trajectory the value of seedin should be kept constant in order to work with the same correlated perturbed atmosphere Reseting the large scale perturbations by modifying the value of seedin between calls to cal1l_mcd to build profiles at a given location should only be done in the context of generating a range of dif ferent possibilities an example is given in table 3 When using the perturbation due to gravity wave propagation small scale perturbation preturkey 3 or 4 to generate a vertical profile the phase ie the value of seedin as well as the associated wavelength gwlength should remain fixed Note that if computing a group of trajectories clustered over a small horizontal distance and at a given martian time then perturbations should not be reset between the computation of each trajectory in order to retain the underlying correlation of the perturbations 21 Note for specialists It has been made possible to keep a given large scale perturbation whilst only changing the gravi
21. ection 11 2 Contents of the Mars Climate database The contents of each subdirectory of the MCD distribution are summarized here docs This directory contains files in pdf formats which can be used to print further copies of the documentation The User Manual user_manual pdf of the database this document This widely used numbering of martian years follows the calendar proposed by R Todd Clancy Clancy et al Journal of Geophys Res 105 p 9553 2000 which begins on April 11 1955 Ls 0 Detailed Design Document det ailed_design pdf of the database v5 0 pdf versions of the scientific reference articles describing various aspects of the Global Climate Model used to compile it are also provided mcd This directory contains Fortran source code for the climate database access softwares see data section 5 and the README file in the directory the CALL_MCD subroutine and a test program Subdirectory testcase contains a simple tool to test the results from the software after installation Subdirectory pres0 contains an autonomous tool to compute surface pressure in the context of high resolution topography see section 3 2 Subdirectories idl matlab scilab c_interface and python contain examples of interfaces of the Fortran subroutine with other languages and softwares The full MCD datasets derived from model runs Essential and common datafiles VL1 1s mgm1025 mola32 nc mountain nc and ps_clim nc
22. ed in the cal1_mcd access software by setting input argument hireskey 1 The now redundant pres0 tool is nonetheless kept as it is a convenient light and autonomous tool for users who only need to retreive high resolution topography and surface pressure More information on how pres0O works is available in the Detailed Design Document 11 1 How to use preso See the README file in subdirectory mcd pres0 This directory also contains e the file pres0 F which contains the pres0O main subroutine and the subroutines it calls and uses e The file testpres0 F which contains a simple example of a program calling preso e The file compile which contains an example of a simple command to compile the programs 11 2 Input output of subroutine preso A call to preso should be as follows call presO dset lat lon solar loctim pres alt ierr e PresO needs 5 input arguments dset character Path to datafiles VL1 1s mola_32 ncandps_MY24 nc These are in the same directory as all the database datafiles The dset string must end with a lat real Latitude coordinate of the point in degrees North lon real Longitude coordinate of the point in degrees East solar real Solar longitude Ls in degrees loctim real Local time in martian hours e And fills 3 output values pres real Surface pressure Pa at given space and time coordinates alt real Above areoid altitud
23. el of the database density and pressure are estimated by integration of the hydrostatic equation assuming a constant temperature For these variables the subroutine delivers mean values and if requested adds a different type of perturbation to density pressure temperature and winds The available types of perturbation are Small scale perturbations due to the upward propagation of gravity waves for any altitudes there is no small scale perturbation for surface pressure Large scale perturbations due to the motion of baroclinic weather systems and other transient waves These perturbations are correlated in longitude and altitude and are reconstructed from the actual system predicted by the model Perturbations equal to n times the RMS day to day variation for all variables The two first types of perturbation have a random component A comprehensive explanation of the perturbations is included in the Detailed Design Document 5 2 Software Package The call_mcd subroutine is in directory mcd This directory includes README a short text file which summarizes the information contained here File call_mcd F which contains the CALL_MCD main subroutine and most of the sub routines and functions it calls the include file constants_mcd inc used by call_mcd and subsidiary routines File test_mcd F which contains a simple and straightforward illustration of a program using call_mcdand julian 3Tn summary th
24. es Ls 0 360 N B The subroutine julian F can be used to compute the Julian date corre sponding to a given calendar date day month year hours minutes seconds on Earth Note that this date essentially matters in order to compute the corresponding solar longitude Ls of Mars and that a different Earth date leading to same Ls will yield identical results localtime real Local true solar time at longitude lon in martian hours Should only be specified if datekey 1 and must be set to zero if datekey 0 N B Local true solar time is such that the sun is highest in the sky at noon A martian hour is defined as 1 24 of a sol a martian day which is 88775 245 s long dset character string dim Path to the directory where the datafiles are to be found dset may be of any size If dset is an empty string then the path to the datasets is set the default path MCD_DATA N B the given path must end with a e g home data on Linux and on Windows scena integer Dust and solar EUV input scenario 1 Climatology Scenario solar EUV average conditions 2 Climatology Scenario solar EUV minimum conditions 3 Climatology Scenario solar EUV maximum conditions 4 dust storm 7 5 solar minimum conditions 5 dust storm 7 5 solar averaged conditions 6 dust storm 7 5 solar maximum conditions 7 warm scenario dusty atmosphere solar max 8 cold scen
25. he atmospheric composition controlled by the photochemistry and the local non condensible gas enrichment and depletion induced by CO2 condensation and sublimation and has been extended into the thermo sphere and model the ionospheric processes The models used to compile the statistics have been extensively validated using available ob servational data and represent the current best knowledge of the state of the Martian atmosphere given the observations and the physical laws which govern the atmospheric circulation and surface conditions on the planet The Mars Climate Database access software add several capabilities to better represent the Mar tian environment variability and accurately compute the surface pressure at high spatial resolution The MCD is freely available online at request Its content may also be accessed to make plots and figures using the interactive server on our WWW site at http www mars lmd jussieu fr 1 1 Available Data The MCD contains several statistics on simulated data stored on a 5 625 x 3 75 longitude latitude grid from the surface up to an approximate altitude of 300 km temperature wind density pressure radiative fluxes atmosphere composition and gases concentration CO ice surface layer statistics on convection etc Fields are averaged and stored 12 times a day for 12 Martian months to give a comprehensive representation of the annual and diurnal cycles Each month covers 30 in solar l
26. inued extvar 61 O volume mixing ratio mol molair extvar 62 O2 volume mixing ratio mol mol extvar 63 O3 volume mixing ratio mol mol extvar 64 H volume mixing ratio mol mol extvar 65 H volume mixing ratio mol mol extvar 66 electron volume mixing ratio mol mol values are only given for pressures higher than 5 107 Pa roughly up to 200 km above the surface above this chemistry ionosphere one would need to model the full ionosphere dynamics which isn t the case here extvar 67 CO column kg m extvar 68 N column kg m extvar 69 Ar column kg m extvar 70 CO column kg m7 extvar 71 O column kg m extvar 72 O2 column kg m extvar 73 O3 column kg m extvar 74 H column kg m extvar 75 Hy column kg m extvar 76 electron column kg m extvar 77 to extvar 100 Not used set to zero seedout real The current index of the random number generator May be used to trigger by setting seedin to this value the generation of a new set of perturbations for the next call to call_mcd 19 Table 2 CALL_MCD output arguments continued ier integer Status code When an error occurs in call_mcd all the out puts arguments pres dens temp zonwind merwind all elements of meanvar and extvar are set to 999 anda message is written to the standard output The value of ier summari
27. lab The IDL tools described above have then been translated into similar matlab scripts initially for MCDv4 0 by Kerri Kusza Stanford University which are available in directory mcd mat lab As with the IDL interfaces data is retrieved from the database via auxiliary Fortran programs Function mcd_mat m along with mcd_mat F can be used to retreive a block of atmospheric data and function profils_mcd_mat m along with profils_mcd_mat F can be used to retrieve a vertical profile of atmospheric data See the README file in the same directory for further comments on adapting these interfaces to your settings 8 Calling the CALL_MCD subroutine from Scilab Scilab is a free open source scientific software similar to Matlab providing a powerful computing environment for engineering and scientific applications Examples of tools similar to those mentionned above and adapted to Scilab by Aymeric Spiga are available in directory mcd scilab As for the Matlab and IDL interfaces described previ ously data is retreived from the database via auxiliary Fortran programs which read and write their 23 inputs and outputs to and from intermediate files The function defined in file mcd sci which calls the Fortran program mcd_sci obtained by compiling mcd_sci F is usefull for retreiving a block of atmospheric data and the function defined in file profils_mcd sci which calls pro gram profils_mcd_sci obtained by compiling Fortran sou
28. may be specified as input The data sets of MCD version 5 0 are completely new compared to previous versions The MCD access software the Fortran routine call_mcd which is essentially the same interface developped for MCD versions 4 2 and 4 3 includes a high resolution mode via postprocess ing of MCD data which combines high resolution MOLA 32 pixels degree topography and atmospheric mass correction from Viking Lander pressure records Examples of interfaces for users interested in calling subroutine call_mcd from C or C programs or IDL Matlab and Scilab softwares are also given Two seperate light tools pres0 which yields high resolution surface pressure and heights which converts various vertical coordinates are also provided For descriptions of the contents and structure of the datafiles details on the dust distribution scenarios a description of the variability models and of the high resolution postprocessing see the Detailed Design Document Contents 1 Introduction 1 1 Available Data 0 0 0 00000 eee ee eee eee 2 Contents of the Mars Climate database 3 Installation 3 1 Software Requirements a 00000 a a Oa ee ee 3 2 Installing the MCD 3 2 4 iire Geet Sa ee BSAA Gre A ee 4 Ways to access the database 5 Using the CALL_MCD subroutine 5 1 What is the CALL_MCD subroutine 0 0 0 2 2 000 5 2 Software Packages di 4 2 4 4 debe sik ve ohh eed ee
29. me correlated perturbed atmosphere seedin real e if perturkey 1 2 3 or 4 Random number generator seed and flag For the first call to cal1l_mcd this value in fact its in teger part is used to seed the random number generator If the value of seedin is changed between subsequent calls to call_mcd it triggers the reseeding of the ran dom number generator and subsequently the regeneration of a new perturbed atmosphere see section 5 5 1 e if perturkey 5 coefficient by which the standard de viation should be multiplied before being added to the mean value seedin is then not allowed to be more than 4 or less than 4 gwlength real Wavelength of the vertical gravity wave in meters Used for small scale perturbations ie if pert urkey 3 or 4 Should be between 2000 and 30000 m if set to 0 then a default value of 16000 m is used N B Feature for specialists Changing the value of gvlength between calls to call_mcd triggers the generation of a new random phase for the gravity wave and without altering the large scale perturbation if the later is also requested i e in the perturkey 4 case extvarkeys integer dim 100 Flags to request extra variables on output Each element 7 of this array signals wether the ith element of optional outputs the ext var array should be given on output if extvarkeys i 0 then extra variable ext var i is not computed note that the 7 first eleme
30. n is defined as the gravitational equipoten tial surface whose average value at the equator is equal to the mean radius as determined by MOLA For more informations see http ltpwww gsfc nasa gov tharsis mola html Depending on the value of flag hireskey references to areoid and topogra phy are with respect to GCM grid or high resolution MOLA data XZ real Vertical coordinate of the requested point Its exact definition depends on the value of input argument zkey xlon real East Longitude planetocentric in degrees xlat real Latitude planetocentric in degrees hireskey integer Flag to set the resolution at which data retrieval and postpro cessing should be done 0 Interpolate data from GCM grid 1 Use high resolution 32 pix deg MOLA topography and areoid as well as some internal post processing scheme to reconstruct data see section 1 3 datekey integer Flag to set the way dates xdate and localtime should be interpreted 0 Earth time xdate is given in Julian days With datekey 0 the localtime argument although un used must be set to zero 1 Mars time xdate is the value of the solar longitude Ls and localtime is the local true solar time at longitude lon given in martian hours 11 Table 1 CALL_MCD Input arguments continued xdate double precision REAL 8 e if datekey 0 the Julian date e if datekey 1 the solar longitude Ls in degre
31. nts of output array ext var are always computed if extvarkeys i 1 then extra variable extvar i is computed 13 Table 2 CALL_MCD output arguments Name Type description pres real Atmospheric pressure Pa dens real Atmospheric density kg m temp real Atmospheric temperature K zonwind real Zonal component of wind in m s gt 0 if eastward merwind real Meridional component of wind in m s gt 0 if northward meanvar real mean atmospheric values dim 5 e meanvar 1 mean atmospheric pressure e meanvar 2 mean atmospheric density e meanvar 3 mean atmospheric temperature e meanvar 4 mean zonal wind e meanvar 5 mean meridional wind This array contains the unperturbed values of pres dens temp zonwind and merwind i e In the perturkey 1 case where no perturbation are requested the meanvar array will contain these extvar real Supplementary variables array dim 100 extvar 1 to extvar 7 provides time and space coordinate which are always computed and are therefore always set Outputs extvar 8 to extvar 76 are only computed and set if the corre sponding input argument ext varkeys i is set to 1 These are otherwise set to zero The rest of the array extvar 77 to extvar 100 is unused yet and always set to zero These available supplementary variables are e extvar 1 Radial distance to planet center m e extvar 2 Altitude above areoid Mars geoid
32. ongitude Ls and is typically 50 70 days long In other words at every grid point the database contains 12 typical days one for each month In addition information on the variability of the data within one month and the day to day oscillations are also stored in the database Software tools are provided to reconstruct and synthetize this variability section 5 1 1 2 Database scenarios Eight combinations of dust and solar scenarios are provided because these are the two forcings that are highly variable from year to year e On the one hand the solar conditions describe variations in the Extreme UV input which control the heating of the atmosphere above 120 km which typically varies on a 11 years cycle Depending on the scenarios solar maximum average and or minimum conditions are provided e On the other hand the major factor which governs the variability in the Martian atmosphere is the amount and distribution of suspended dust Because of this variability and since even for a given year the details of the dust distribution and optical properties can be uncertain multi annual model integrations were carried out for the database assuming various dust scenarios i e prescribing various amount of airborne dust in the simulated atmosphere 4 dust scenarios are proposed 1 The Climatology clim scenario which is an ensemble average of simulations ran using the latest version of the LMD Global Climate Model GCM fo
33. r 19 Surface pressure Pa high resolution if hireskey 1 GCM surface pressure if hireskey 0 e extvar 20 GCM surface pressure Pa will be equal to extvar 19 if hireskey 0 N B Provided for specialist interested in the differences between low resolution i e the GCM resolution and high resolution surface pres sures 15 Table 2 CALL_MCD output arguments continued e extvar 21 Atmospheric pressure RMS day to day varia tion Pa if zkey 1 2 or 3 Otherwise set to zero e extvar 22 Surface pressure RMS day to day variations Pa e extvar 23 Atmospheric temperature RMS day to day variations K N B The given RMS is either pressure wise if zkey 4 or altitude wise if zkey 1 2 or 3 e extvar 24 Zonal wind RMS day to day variations m s N B The given RMS is either pressure wise if zkey 4 or altitude wise if zkey 1 2 or 3 e extvar 25 Meridional wind RMS day to day variations m s N B The given RMS is either pressure wise if zkey 4 or altitude wise if zkey 1 2 or 3 e extvar 26 Vertical wind m s positive when down ward e extvar 27 Vertical wind RMS day to day variations m s N B The given RMS is either pressure wise if zkey 4 or altitude wise if zkey 1 2 or 3 e extvar 28 Small scale density perturbation gravity wave kg m e extvar 29 Not used set to zero e extvar 30 Surface roughness length zo m 16 Table 2
34. rce code profils_mcd_sci F can be used to retreive a vertical profileof atmospheric data There is moreover a short script mcd_plot sci which illustrates the use of these functions Once the Fortran routines adapted and compiled see the README compile_mcd_sci and compile_profils_sci files this demo may be lauched with the following command scilab f mcd_plot sci 9 Calling the CALL_MCD subroutine from C or C programs Examples of C and C programs interfaced with the Fortran subroutine call_mcd are given in the mcd c_interfaces subdirectory These files along with the header file mcd h illustrate how to call the Fortran subroutines call mcd and julian from C test_emcd c and C test_emcd cpp main programs Unfortunately inter language calling conventions vary with compilers and operating systems although the C and C interfaces have been tested on our Linux systems using Gnu compilers gfortran gcc g as well as Portland Group compilers pgfortran pgec pgCC they will certainly need to be adapted to your settings Some examples of compiling and linking commands are given in the provided Makefile and README files To summarize compiling and linking in order to build the main C or C program requires the following steps 1 Create the object files corresponding to the Fortran subroutines which will be called by the main program e g gt pgf90 c julian F gt pgf90 c heights F I path to netcdf incl
35. rced by the dust distributions observed during Mars Years 24 26 27 29 and 30 years without global planet encircling dust storms This Climatology scenario is provided with 3 solar EUV conditions solar min solar ave solar max 2 The cold scenario corresponds to an extremely clear atmosphere Low dust scenario where the dust opacity at a given location is set to be the minimum observed over Mars years 24 30 further decreased by 30 topped with a solar minimum thermosphere 3 The warm scenario corresponds to dusty atmosphere conditions but nonetheless non dust storm conditions the dust opacity at a given location is set to the maximum observed unless during a global dust storm further increased by 30 topped with a solar maximum thermosphere 4 The dust storm scenario represents Mars during a global dust storm dust opacity set to 7 5 at all times and over the whole planet Moreover the dust optical properties are for this case set to represent darker dust than nominal in practice for these runs Ockert Bell et al dust properties were used rather than the more recently derived Wolff et al ones This scenario is only provided for when such storms are likely to happen during northern fall and winter Ls 180 360 but with 3 cases of solar EUV inputs solar min solar ave solar max The cold and warm annual scenarios are provided to bracket the possible global condi tions on Mars outsi
36. rectory with names starting with st rm have been compressed gzipped and should be un compressed gunzipped before being used Differences between version 4 2 and version 4 1 e Version 4 2 uses the same database datafiles as version 4 1 except for a small subset the files which contain variability most improvements changes and new features are in the access and postprocessing software e The main new features and differences are 1 The main Fortran subroutine to retrieve data from the database is now called call_mcd and significant changes to the argument list compared to its predecessor atmemcd have been introduced A new high resolution procedure based on the integration of high resolution 32 pixels per degree MOLA topography has been implemented Input and output arguments which are floating numbers are now declared as sin gle precision i e Fortran REAL except xdate which is double precision i e Fortran REAL 8 27 2 3 4 The way by which users impose date and local time has changed Input longitude and latitude must now be given in degrees Longitude is inter preted as degrees east as before Input arguments used to signal and generate perturbations have been changed Day to day variability of atmospheric variables is now given either pressure wise or altitude wise depending on the vertical coordinate selected by the user Examples of interface
37. rmal IR on the ground and at the top of the atmosphere e Wind speed defined by two components the meridional wind positive when oriented from south to north the zonal wind positive when oriented from west to east e Vertical wind e The main atmospheric composition CO2 N2 Ar CO O volume mixing ratio e Mixing ratios of trace gases such as O2 O3 H H e Electron mixing ratio up to 200km e Water vapour and water ice content e Column values of all species e Dust aerosol opacity and distribution e Air viscosity heat capacity and Cp C ratio e Sensible heat flux and surface stress e Key convective plantery boundary layer PBL variables maximum convective updraft and downdraft velocities in the PBL PBL height convective vertical wind variance and convec tive eddy vertical heat flux The Fortran subroutine cal 1_mcd retrieves database data at any date Earth date or Mars season and time and at any point in space defined by latitude and east longitude and a vertical coordinate which can be a distance from the planet center an altitude or a pressure level The returned values of meteorological variables are computed by interpolation in space time of day and month from data stored in the MCD As of version 4 2 of the MCD an additional high resolution interpolation procedure which uses 32 pixels degree MOLA topography has been implemented to simulate local pressure and density as accurately as possible Above the top lev
38. s0 which contains the preso tool see section 11 subdirectories idl matlab scilab c_interfaces and python which contain ex amples of interfaces 5 3 Compiling and running CALL_MCD A simple program using the cal 1_mcd subroutine as well as the complementary subroutine julian called test _mcd is provided in the mcd directory You can easily modify it or use part of this code for your own purpose To compile the program edit the compile file and make the necessary changes e g compiler name path to NetCDF library and include file see comments in the script Then for instance to compile and run fest_mcd type gt compile gt test_mcd your computer using test _mcd is provided Please read mcd testcase RI information Then just answer the questions Alternatively you can edit the file test mcd def and redirect it to test _mcd gt test_mcd lt test_mcd def If the program return an error see the list of return error codes in table 2 to identify the proble In the mcd testcase sub directory a tool to test that cal1_mcd is running accurately If your machine runs under Windows you have 2 solutions m on EADME for further 1 Install a Unix environment emulator for Windows The most popular is Cygwin which you can download from http www cygwin com This emulator includes most Unix fea tures and softwares NetCDF libraries can be built on Cygwin as easely as on other Unix systems As far as a few te
39. ses the status of call_mcd 0 OK no error 1 Wrong vertical coordinate flag zkey Wrong choice of dust scenarion scena Wrong value for perturbation flag perturkey Wrong value for high resolution flag hireskey Wrong value for date flag datekey Wrong value for extra variables output flag extvarkey Wrong value for latitude xlat o u NN FW WN Inadequate value for gravity wave wavelength gwlength 9 Wrong value of input solar longitude xdate must be in 0 360 in the datekey 1 case 10 Given Julian date xdate in the datekey 0 case im plies an Earth date outside of 1800 2200 range 11 Wrong value of local time in the datekey 1 case which should be in 0 24 12 Incompatible localtime0 and datekey 0 13 Unresonable value of seedin in perturkey 5 case 14 No dust storm scenario available at such date 15 Could not open a database file dset is probably wrong 16 Failed loading data from a database file 17 Sought altitude is underground 18 adding perturkey 5 perturbation yields unphysical density 19 adding perturkey 5 perturbation yields unphysical temperature 20 adding perturkey 5 perturbation yields unphysical pressure 5 5 The right use of the CALL_MCD subroutine 5 5 1 Perturbed atmospheres In addition to the mean atmospheric state the user may obtain a realisticly perturbed using input flag perturkey atmosphere The perturbation consisting of adding n times
40. set xlat xlon hireskey convkey amp zradius zareoid zsurface ier where input and output arguments are e dset character Path to the datafiles the routine needs If left empty e g dset the default path MCD_DATA is assumed e xlon real East planetocentric longitude in degrees e xlat real North planetocentric latitude in degrees e hireskey integer Flag to set the resolution 0 GCM resolution 1 high resolution e convkey integer Switch to indicate which distance is known and used to find the other two convkey 1 zradius is known compute zareoidand zsurface convkey 2 zareoid is known compute zradius and zsurface convkey 3 zsurface is known compute zradius and zareoid e zradius real distance to center of planet m e zareoid real altitude above areoid m e zsurface real altitude above local surface m e ier integer Routine status error code 0 if all went well see file heights F 26 A Differences Between Version 5 0 and Previous Versions of the MCD Differences between version 5 0 and version 4 3 e The main change in MCD version 5 0 is in the fact that the database files result from sim ulations using the latest version of the LMD GCM which includes many improvements compared to the version that was used to derive MCDv4 x datafiles e Other changes which have been introduced are The EOFs Empirical Orthogonal Functions for larg
41. software for C C and Scilab users have been added in addi tion to the pre existing IDL and Matlab ones Computation of solar longitude from a given Julian date has been made more accurate Computation of local time given in true solar time has been improved by using an appropriate equation of time The presO tool has been updated Lists of changes and improvements of previous versions of the MCD e Version 4 1 is similar to beta version 4 0 with some improvements and a few problems fixed e The main differences between version 4 and previous version 3 1 are The database now extends up to the thermosphere and new variables upper atmospheric composition CO2 N2 CO O H and in the lower atmosphere water water ice ozone dust are available 2 Different vertical coordinates may be specified as input including pressure level 3 A linear interpolation in time Ls for mean variables between seasons was added 4 For some variables an estimation of the day to day variation is provided root mean square values There is a significant re arrangement of arguments of atmemcd so that all the input variables are followed by all the output variables 6 We suggest the use of direct compilation rather than using the UNIX command make 7 Variables are now saved in atmemcd to fix problems with F77 compilers which don t 10 11 store values of variables between subroutine calls The da
42. sts have shown requirements and steps necessary to install the Mars Climate Database and use the provided access software under Cygwin are in fact the same as those for standard Unix systems Port the Mars Climate Database to Windows We have not fully tested that possibility but sev eral users have done so successfully NetCDF librairies for Windows can be dowloaded from the NetCDF official website at http www unidata ucar edu packages netcdf Note that with Windows the symbolic link strategy to the Mars Climate Database data Tn the examples given here the gt at the begining of command lines is the Unix session command prompt directory described in section 3 2 will not work the true path to that directory must be used in the Fortran routines and programs see variable dset in the description of call_mcd arguments in section 5 4 5 4 CALL MOD input and output arguments A Fortran call to subroutine cal1_mcd should look something like call_mcd zkey xz xlon xlat hireskey datekey xdate localtime dset scena perturkey seedin gwlength extvarkeys pres dens temp zonwind merwind RQ R RR meanvar extvars seedout ier All the input arguments ie values which must be set before calling the routine and which are not altered by it are described in table 1 Outputs are described in table 2 MCDv 4 3 users should note that the only change in the argument list is with input argument e
43. tabase now has a more accurate representation of gravity the fact that it varies following an inverse square law is accounted for when integrating the hydrostatic equa tion The variation of R the gas constant with altitude is also taken into account The horizontal resolution of the database has changed to 5 625 x 3 75 longitude x latitude We now provide the separate tool to compute surface pressure with high accuracy We now provide some tool to use the database software from IDL e A major change in Version 3 1 compared to version 3 0 of the database is the change from DRS data format to NetCDF A bug was also fixed for the calculation of large scale variability in the upper atmosphere above 120 km e The main differences between version 3 0 and 2 3 are mostly related to the content of the database files due in particular to improvements made in the models used to build the database including an extension of the model top from 80 to 120 km improved surface properties and a dust scenarios from Mars Global Surveyor e The main difference between version 2 3 and 2 0 is the use of the main subroutine AT MEMCD which computes meteorological variables from the Mars Climate Database MCD 28 e The main difference between version 2 0 and 1 0 of the MCD is that the large scale variabil ity model now makes use of two dimensional multivariate Empirical Orthogonal Functions EOFs These now describe correlations in the model
44. the standard deviation to the mean value the perturkey 5 case must not be used to create randomly perturbed atmospheres but only as a mean to globally overestimate or underestimate the profiles of the meteorological variables To 20 Table 3 Example of Fortran code to illustrate the use of re setting perturbations build a density profile at a given time and location with EOF and GW perturbations perturkey 4 seedin 100 seed perturbations zkey 3 work in altitude above local surface coordinate do i 1 100 XZ i 1 2000 0 go from surface to 200km call_mcd zkey xz xlon xlat hireskey amp datekey xdate localtime dset scena amp perturkey seedin gwlength extvarkeys amp pres dens temp zonwind merwind amp meanvar extvar seedout ier profile 1l i dens store density enddo some code here moved on to a different time or place far from previous one l such that perturbations should be reset seedin seedout change seedin to regenerate perturbations build the new density profile do i 1 100 XZ i 1 2000 0 go from surface to 200km call_mcd zkey xz xlon xlat hireskey amp datekey xdate localtime dset scena amp perturkey seedin gwlength extvarkeys amp pres dens temp zonwind merwind amp meanvar extvar seedout ier profile 2 i dens store density enddo generate randomly perturbed atmospheres you must us
45. ty wave small scale perturbation between calls This is achieved by changing the value of input argument gwlength between calls to call_mcd This feature which should be usefull to people who might want to generate realistic longitude height or latitude height slices over large horizontal distances over which indeed gravity waves should not correlate requires some sensible choices in longitude latitude spacing and gravity waves reseeding It is meant for experienced users and not advised for general use 5 5 2 Running time In order to minimize computational time the datasets corresponding to encompassing months of sought input date of a given MCD dust and EUV scenario are loaded from the database at the first call of the call_mcd subroutine This initial loading is time consuming but once loaded these values can then be used for further calls as long as the sought dates do not lead to a change in bracketing months This should be taken into account when simulating trajectories or maps over more than a month calls to cal1l_mcd should be ordered so that all data is gathered within each 30 range of Ls 15 to 45 45 to 75 Similarly only required data sets are loaded if for instance no perturbations are requested then only mean values are loaded Note that requesting perturbations perturkey set to 2 3 or 4 as well as supplementary outputs elements of ext varkeys set to 1 implies extra computations which will slow down
46. ude gt pgf90 c call_mcd F I path to netcdf include which will create objects julian o call_mcd oandheights o 2 Compile the main program e g test_mcd c with your C or C compiler gt pgcc test_mcd c call _mcd o julian o heights o I path to netcdf include L path to netcdf lib l netcdt you will need to add other libraries to ensure good Fortran C C compatibility but these are extremely compiler and platform dependent check your compiler s manual for instructions 10 Calling the CALL_MCD subroutine from python An exemple of a python script calling the Fortran subroutine cal l_mcdis given in the mcd python subdirectory Note that in order to interface the MCD software with python one must first create the corre sponding python interface using the provided fmcd_gfortran sh script adequately adapted as explained in the README file in the directory The provided test_mcd py script illustrates how one can implement a call to the MCD from python 11 High accuracy surface pressure tool preso The subdirectory mcd pres0 contains a tool specifically designed to compute surface pressure as well as surface altitude above the areoid at any location and time on Mars outside global dust 24 storm data corresponding to the Climatology scenario is used with the best accuracy currently possible As of version 4 2 of the Mars Climate Database this feature and its extention to atmospheric variables is includ
47. xt varkeys which is now an array see table 1 As call_mcd runs it writes informational and error messages to standard output Users who wish to run call_mcd silently i e without any messages sent to standard output should edit file constants_mcd inc and change the value of parameter output_messages to false As of version 4 3 the standard output unit number which will be used by call_mcd is set to the value of the out parameter also defined in file constants_mcd inc The default value of out is 6 which is the standard value preconnected to the screen on most systems Setting out to any other positive integer value n except 5 which is usually preconnected to standard input will send messages to the corresponding file It is thus advised to open the corresponding file using Fortran command open unit n file myfilename prior to any call to call_mcd otherwise default file fort n will be used this behaviour is possibly system dependent 10 Table 1 CALL_MCD Input arguments Name Type Description zkey integer Flag to set the type of vertical coordinate xz is given as 1 xz is the radial distance from the center of the planet m 2 xz is the altitude above the Martian zero datum Mars geoid or areoid in meters 3 xz is the altitude above the local surface m 4 xz is the pressure level Pa 5 xz is the altitude above reference radius 3 396 10 m m N B The zero elevatio
48. you can install the Grid Analysis and Display System GrADS or Ferret which are fine free softwares for displaying graphical output from geophysical datasets GrADS and Fer ret can read NetCDF files and display their contents using a few easy instructions Both works on Unix Linux and Windows environments and can be downloaded from their respective World Wide Web servers http grads iges org grads http ferret pmel noaa gov Ferret There are also freely available plotting tools such as neview ncBrowse or Panoply which can be used to visualize NetCDF files IDL users can also read and display the raw datafiles using the read_ncdf pro IDL function available on many websites Please note that the vertical coordinate in the datafiles are terrain following sigma pressure hybrid coordinates The altitude coordinate given in the datafiles is merely an approximation of the real altitude of the data The Fortran access software calculates heights accurately by integrating the hydrostatic equation directly on the hybrid coordinates 5 Using the CALL_MCD subroutine 5 1 What is the CALL_MCD subroutine The purpose of the cal1l_mcd subroutine is to extract and compute meteorological variables use ful for atmospheric trajectory computations as well as scientific studies Data which may thus be obtained includes e Atmospheric and surface pressure e Atmospheric and surface temperature e Density e Radiative fluxes Solar and the
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