MARS CLIMATE DATABASE v4.3 USER MANUAL
Contents
1. 30 levels Data Filename scen _ mon _t hermo_ solar _ type filename extension for ther mospheric files from around 130km up to around 250km 20 levels scen denotes the dust scenario type MY24 cold warm strm this last scenario beiing the global dust storm scenario where mon denotes the month number mon O01 is month 1 Ls 0 30 mon 02 is month 2 Ls 30 60 mon 03 is month 3 Ls 60 90 mon 04 is month 4 Ls 90 120 gt 05 is month 5 Ls 120 150 mon 06 is month 6 Ls 150 180 gt 07 is month 7 Ls 180 210 mon 08 is month 8 Ls 210 240 gt 09 is month 9 Ls 240 270 mon 10 is month 10 Ls 270 300 5 gt 11 is month 11 Ls 300 330 mon 12 is month 12 Ls 330 360 mon all is the whole year for the Empirical Orthogonal Functions EOF data for the large scale variability model 3 5 5 5 MON 3 5 I type indicates the type of data in the file 42 type me means mean data type sd means standard deviation data and rms data type eo means EOF data for large scale perturbations solar indicates the type of solar scenario for thermosphere2. Create a working directory e g mars on a disk where you wish to use the database 2 Copy the following directory from the DVD rom to this location at least mcd and if needed docs 3 If possible you should copy the data from the DVD ROM to your hard disk The data can be accessed directly from the DVD ROM see below but this last solution is slower and less convenient We suggest that you copy the directory data from the DVD ROM to the working directory mars for in stance or to another disk if there is not enough disk space available there see how to link datafiles and software below Moreover as of MCD version 4 3 storage requirements have imposed that some of the data files be com pressed gzipped and should be uncompressed gunzipped i e gunzip file gz on Unix machines any of the many standard de compression tool will do on other platforms prior to being used Only files containing data for dust storm scenarios i e files in the data directory whith a name starting with st rm have been compressed This way the MCD can still be run with all the data remaining on the DVD the dust scenario obviously cannot be used then A full installation of the MCD takes about 4 5 Gb of disk space Note that the amount of disk space needed may be reduced by only retaining a limited range of dust scenarios or seasons of interest within the data subdirectory see Appendix A for a quick description of database file contents 4 In the w
3. 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 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 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 21 Table 1 CALL_MCD Input arguments continued integer Dust and solar EUV input scenario 1 MY24 dust Scenario solar minimum conditions 2 MY24 dust Scenario solar averaged conditions 3 MY24 dust Scenario solar maximuml conditions 4 dust storm 7 4 solar minimum conditions 5 dust storm 7 4 solar averaged conditions 6 dust storm 7 4 solar maximum conditions 7 warm scenario Viking lander dust solar max 8 cold scenario low dust 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 distribut
4. Mars Climate database Installation 4 1 Software Requirements 000 4 2 Installing the MCD from the DVD rom Ways to access the database Using the CALL_MCD subroutine 6 1 What is the CALL_MCD subroutine 20 6 2 Software Package 2 ee ee 6 3 Compiling and running CALL_MCD 6 4 CALL_MCD input and output arguments 6 5 The right use of the CALL_MCD subroutine 6 5 1 Perturbed atmospheres 0 10 11 11 12 13 15 10 11 12 6 5 2 Runningtime 04 Calling the CALL_MCD subroutine from IDL Calling the CALL_MCD subroutine from Matlab Calling the CALL_MCD subroutine from Scilab Calling the CALL_MCD subroutine from C or C programs High accuracy surface pressure tool preso 11 1 HowtousepresO 0 0202 2 e eee 11 2 Input output of subroutine presO 200 The heights tool 12 1 Arguments of heights subroutine 0 Accessing the database without using the CALL_MCD subroutine A 1 Content of the database files 00 A 2 Using the NetCDF Library 0 A 2 1 Opening and Closing Files 0 A 2 2 Manipulating Data 00 34 37 37 38 39 39 39 40 41 42 1 Introduction The Mars Climate Database MCD is a database of atmospheric statistics com piled f
5. between 5 107 and 1 110 seconds as shown in Table 4 7 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 34 The mcd id1 subdirectory contains two tools which show how the callmcd 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 vertical 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 tem perature 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
6. 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 resolu tion 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 seper ately e subdirectory pres0 which contains the pres 0 tool see section 11 e subdirectories idl matlab scilaband c_interfaces which contain examples of interfaces 17 6 3 Compiling and running CALL_MCD A simple program using the cal1l _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 ie compiler name path to NetCDF library and include file Then For instance to compile and run test_mcd type gt compile gt test_mcd Then just answer the questions Alternatively you can edit the file test mcd def and redirect it to test mcd gt test imcd lt test_mcd def In the mcd testcase sub directory a tool to test that call_mcd is run ning accurately on your computer using test _mcd is provided Please read mcd testcase README for further information If your machine ru
7. interpreted 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 coordi nate selected by the user 2 Examples of interface software for C C and Scilab users have been added in addition to the pre existing IDL and Matlab ones 3 4 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 pres0 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 10 11 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 Different vertical coordinates may be specified as input including pres sure level A linear interpolation in time Ls for mean variables between seasons was added For some variables an estimation of the day to day variation is pro vided root mean square values There is a significant re arrangement of arguments o
8. meanvarz will be DBLARR 5 1 nlat nlon gt 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 For tran code and thus follow the call _mcd subroutine outputs given in section 6 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 cur rent directory 2 Edit the the Fortran code mcd_id1 F which is used by IDL to call call_mcd and set the path the dset variable to the MCD data di rectory 3 Compile the Fortran code mcd_idl F You may use the script compilemcd_id1 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 gt When multidimensinal data is sought dimensions are arranged as follows mean varz 6 nlat nlon nz nLs nloctime 35 e profils mcd_idl pro is an IDL procedure that can be used to retrieve atmo spheric profiles for a list of horizontal coordinates and times This is espe cially useful to emulate observations of atmospheric profiles from an instru ment 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 hig
9. resolution e convkey integer Switch to indicate which distance is known and used to find the other two convkey 1 zradius is known compute zareoid and 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 41 A Accessing the database without using the CALL_MCD subroutine A 1 Content of the database files The file structure of the data directory is discussed in the Detailed Design Docu ment for the MCD Tables which show the variables available are reproduced here for convenience mean data files me contain 12 monthly mean values corre sponding to 12 Solar times of day for the variables shown in Tables 5 and 6 and standard deviation data files sd contain the monthly standard deviation values and the day to day root mean square RMS variability of of the variables in Ta bles 7 and 8 For a gain of space files are divided in low atmospheric files and thermospheric files thermo or not in the file name The file naming convention for each file with filename extension nc is as fol lows Data Filename scen _ mon _ type filename extension for low atmospheric files up to around 130km
10. which uses profils mcd_idl pro 36 8 Calling the CALL_MCD subroutine from Matlab The IDL tools described above have been translated into similar matlab scripts by Kerri Kusza Stanford University which are available in directory mcd matlab 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 atmo spheric data See the README file in the same directory for further comments on adapting these interfaces to your settings 9 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 previously data is retreived from the database via auxil iary Fortran programs which read and write their 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 profilsmcd sci which calls program profi
11. 74 Anz 5 5 1074 Aco 4 87 1074 and Aar 3 41074 e extvar 51 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 29 Table 2 CALL_MCD output arguments continued 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 and a message is written to the standard output The value of ier summarises 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 Inadequate value for gravity wave wavelength gwlength Wrong value of input solar longitude xdate must be in 0 360 in the datekey 1 case Given Julian date xdate in the datekey 0 case im plies an Earth date outside of 1800 2200 range 30 Table 2 CALL_MCD output arguments continued 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 ca
12. MARS CLIMATE DATABASE v4 3 USER MANUAL ESTEC Contract 11369 95 NL JG Mars Climate Database and Physical Models CNES Contract Base de donn es climatique martienne F Forget E Millour LMD Paris S R Lewis The Open University Milton Keynes April 2008 Abstract This document is the User Manual for version 4 3 of the Mars Climate Database MCD developed 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 General Circula tion Model GCM numerical simulations of the Martian atmosphere This document replaces previous 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 statis tics on temperature wind pressure radiative fluxes it provides data such as atmospheric composition including dust water vapor and ice content and make use of improved dust and Extreme UltraViolet EUV scenarios to represent the variation of dust in the atmosphere and solar EUV conditions Linear 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 coo
13. al depth N B DOD is in fact deduced from the dust opacity retrieved by M Smith GFDL from MGS TES at 1075 cm multiplied by 1 65 To estimate a true visible extinction optical depth we suggest to multiply DOD by about 1 2 extvar 37 Dust mass mixing ratio kg kgair extvar 38 Dust Optical Depth RMS day to day varia tions extvar 39 Not used set to zero extvar 40 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 28 Table 2 CALL_MCD output arguments continued e extvar 41 Water vapor vol mixing ratio mol mol e extvar 42 Water ice column kg m2 e extvar 43 Water ice mixing ratio mol mol e extvar 44 O3 ozone volume mixing ratio mol mol set to 0 above the 4 1074 Pa level which is around 120 km e extvar 45 CO2 volume mixing ratio mol mol set to 9 532 107 when below the thermosphere which starts at 90 km e extvar 46 O volume mixing ratio mol mol e extvar 47 N2 volume mixing ratio mol mol set to 0 027 when below the thermosphere e extvar 48 CO volume mixing ratio mol mol set to 8 1074 when below the thermosphere e extvar 49 R Molecular gas constant J kg K e extvar 50 Air viscosity v estimation N s m N B v AT 9 0 25 4Cp 5R with A SAjyymri where umri is the vol mixing ratio of specy i and Aco2 3 07 10 4 Ao 7 6 10
14. broutine ATMEMCD which computes meteorological variables from the Mars Climate Database MCD e The main difference between version 2 0 and 1 0 of the MCD is that the large scale variability model now makes use of two dimensional multivari ate Empirical Orthogonal Functions EOFs These now describe correla tions in the model variability as a function of both height and longitude rather than solely of height as in version 1 0 3 Contents of the Mars Climate database The contents of each subdirectory of the MCD provided on the DVD are summa rized 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 docu ment pdf versions of the scientific reference articles Lewis et al 1999 and Forget et al 1999 describing earlier Mars Climate database and the General Circulation models used to compile it are also provided mcd This directory contains Fortran source code for the climate database ac cess softwares see section 6 and the README file in the directory the CALL_MCD subroutine and a test program 10 data Subdirectory testcase contains a simple tool to test the results from the software after installation Subdirectory pres0 contains an autonomous tool to compute surface pres sure in the context of high resolution topography see section 4 2 Subdirectories idl matlab scilab and c_int
15. ct 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 K 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 25 Table 2 CALL_MCD output arguments continued extvar 11 Not used set to zero extvar 12 Not used set to zero extvar 13 Scale height H p m 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 extvar 15 Surface temperature K extvar 16 Daily maximum mean surface temperature K extvar 17 Daily minimum mean surface temperature K extvar 18 Surface temperature RMS day to day varia tions K extvar 19 Surface pressure Pa high resolution if hireskey 1 GCM surface pressure if hireskey 0 extvar 20 GCM surface pressure Pa will be equal to extvar 19 ifhireskey 0 N B Provided for specialist interested in the differences between low resolution i e the GCM resolution and high resolution surfac
16. d meanvar extvar seedout ier RQ R RR 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 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 const ants_mcd inc and change the value of parameter output _messagesto 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 ince 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 ex cept 5 which is the usually preconnected to standard input will send messages to the corresponding file It is thus advised to open the corresponding file using For tran 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 19 Table 1 CALL_MCD Input arguments 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 xz is the altitude above the
17. e pres sures 26 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 q2 turbulent kinetic energy m s e extvar 30 Not used set to zero 27 Table 2 CALL_MCD output arguments continued extvar 31 Thermal IR A gt 5m flux to surface W m extvar 32 Solar flux 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 optic
18. ed 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 6 5 1 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 Wavelength of the vertical gravity wave in meters Used for small scale perturbations ie if perturkey 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 gwlength 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 Flag to request extra variables on output 0 extra variables not computed only the 7 first elements of output array extvar will be filled Faster computations 1 extra variables computed and returned in output argument array extvar 23 Table 2 CALL_MCD output arguments meanvar real mean atmospheric values dim 5 meanvar 1 mean atmospheric pressure meanvar 2 mean atmospheric density meanvar 3 mean atmospheric temperature meanvar 4 mean zonal wind meanvar 5 mean meridional wind This array contains the un
19. el 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 ac curately 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 pres 0 see section 11 2 Differences Between Version 4 3 and Previous Versions of the MCD 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 arbitrar ily set to 3 39610 m The output unit to
20. ength extvarkey pres dens temp zonwind merwind meanvar extvar seedout ier profile 2 i dens store density enddo 33 Table 4 Illustrative example of the impact of cal1l _mcd options on its run time Given times were obtained on a 64 bit Linux 3 0GHz Xeon dual core computer Values given for initial call correspond to the very first call to the routine while those for subsequent calls corespond to the time required for subsequent calls to the routine as long as no new data sets need be loaded perturkey l call perturkey 2 call 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 call_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 ext varkey set to 1 implies extra computations which will slow down the program On a 64 bit Linux 3 0GHz Xeon dual core computer the first call to call_mcd may take between 0 5 and 2 seconds depending on whether high resolution and or perturbations and or extra outputs the three most time consuming options are re quested but subsequent calls as long as no new data sets need be loaded require
21. erface contain exam ples of interfaces of the Fortran subroutine with other languages and soft wares The full MCD datasets derived from model runs The database is contained in one DVD ROM You can should copy the entire database on your hard disk and also decompress some of the data files see section 4 2 4 Installation 4 1 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 Fortran77 for which a Fortran compiler 77 90 95 etc 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 Nevertheless it has not been fully tested by the our team but we can confirm that it compiles fine under the Cygwin environment on Windows using the GNU g77 compiler The data in the MCD are written using the Network Common Data Form NetCDF software It was developed as part of Unidata a National Science Foundation sponsored program see Detailed Design Document for more de tails The libraries are 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 11 4 2 Installing the MCD from the DVD rom 1
22. f atmemcd so that all the input variables are followed by all the output variables We suggest the use of direct compilation rather than using the UNIX command make Variables are now saved in atmemcd to fix problems with F77 compil ers which don t store values of variables between subroutine calls The database 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 equation The variation of R the gas con stant 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 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 su
23. files solar min for minimum solar ave for average solar max for maximum Sean arable Pym Panis Bes Surface temperature tsurf Surface pressure ps LW thermal IR radiative flux to surface fluxsurf_lw SW solar radiative flux to surface fluxsurf_sw LW thermal IR radiative flux to space fluxtop_lw SW solar radiative flux to space fluxtop_sw CO ice cover co2ice Water vapor column col_h2ovapor Water ice column col_h2oice Visible Dust optical depth Atmospheric density kg m Atmospheric temperature K Zonal East West wind mst Meridional North South wind ms Vertical up down wind ms Boundary layer eddy kinetic energy m s7 Water vapor mixing ratio vmr_h2ovapor mol mol Water ice mixing ratio vmr_h2oice mol mol Ozone O3 mixing ratio vmr_o3 mol mol Table 5 Variables stored in database mean data files low atmosphere A 2 Using the NetCDF Library Data in the MCD are written in NetCDF format If you are not using a package such as GrADS or Ferret which can read NetCDF format you can write a program in Fortran or some other language such as C or IDL to access the data using the 43 Atmospheric density kg m Atmospheric temperature K Zonal East West wind ms Meridional North South wind ms Vertical up down wind ms O volume mixing ratio vmr_o mol mol CO2 volume ratio vmr_co2 mol mol CO mixing ratio vmr_co mol mol N mixing ratio vmr_ n2
24. from MGS TES observations using data assimilation technique The MY24 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 dust opacity 7 0 1 topped with a solar minimum thermosphere 3 The warm scenario corresponds to dusty atmosphere for the season scenario but not a global dust storm topped with a solar maximum thermosphere 4 The dust storm scenario represents Mars during a global dust storm dust opacity set to 7 4 Only available when such storms are likely to happen during northern fall and winter Ls 180 360 but with 3 solar EUV conditions solar min solar ave solar max This corresponds to the 24th martian year according to the calendar proposed by R Todd Clancy Clancy et al Journal of Geophys Res 105 p 9553 2000 which starts on April 11 1955 Ls 0 The cold and warm annual scenarios are provided to bracket the possible global conditions on Mars outside global dust storms which are thought to be highly variable locally and from year to year 1 3 High resolution mode The Mars Climate Database has been compiled from the output of a general circula tion model in which the topography is very smoothed because of its low resolution In addition the pressure variations due to the CO2 cycle condensation of atmo spheric CO2 in the polar caps that is computed by the mod
25. h contains the pres0 main subroutine and the sub routines it calls and uses e The file testpres0 F which contains a simple example of a program call ing preso e The file compile which contains an example of a simple command to com pile the programs 11 2 Input output of subroutine preso A call to preso should be as follows The only files that presO requires are VL1 1s mola32 nc and ps_MY24 nc Users inter ested in installing only presO and not the whole database should copy these files which are in the data directory to their hard disk 39 call presO dset lat lon solar loctim pres alt ierr e PresO needs 5 input arguments dset characters Path to datafiles VL1 1s mola_32 nc and ps 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 coordi nates alt real Above areoid altitude of the surface m at given space coordinates ierr integer control variable 0 if all is ok 12 Theheights tool The call_mcd routine handles and converts various types of vertical coordinates as explained
26. h resolution mode hireskey on 1 off 0 and vertical coordinate 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 ex cept that they are arrays containing the profiles for the list of hori zontal and time coordinates For instance meanvarz has the follow ing dimension DBLARR 5 1 number of profiles number of point in each profile 5 1 means here that contrary to the usual IDL con vention 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 6 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 cur rent 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 compileprofils_mcd_idl after having edited it to match your needs 4 Call profilsmcd_idl pro from IDL using your favorite method the file test _profils_idl pro is an example of an IDL program
27. hts F I path to netcdf include gt 77 c call mcd F I path to netcdf include which will create objects julian o callmcd oandheights o 2 Compile the main program e g test_mcd c with your C or C com piler gt cc test mcd c call mcd o julian o heights o I path to netcdf include L path to netcdf lib I netedt you will surely need to add other libraries e g 1f2c or 1g2c for the GNU compilers but these are extremely compiler and platform dependent check your compiler s manual for instructions 38 11 High accuracy surface pressure tool preso The subdirectory mcd pres0O contains a tool specially designed to compute sur face pressure as well as surface altitude above the areoid at any location and time on Mars outside global dust storm data corresponding to the MY24 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 included in the call_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 Howto use preso See the README file in subdirectory mcd pres0O This directory also contains e the file pres0O F whic
28. ime of year as well as for time of day e var3d Retrieves the value of a 3 D field from the MCD Uses trilinear in terpolation from the database grid point values in longitude latitude and altitude e profi Reads a vertical profile from a 3 D field on model levels Uses bi linear interpolation to compute values of variables at the user specified lon gitude and latitude and time e get si Solves the hydrostatic equation to find the value of pressure altitude corresponding to the user specified input and compute vertical interpolation weights 46 orbit Computes for a given Julian date coresponding solar longitude Ls Sun Mars distance and GCM model day mars_ltime This routine computes true solar time at a particular longitude for a given Julian date Ls set sol21s This routine computes the solar longitue Ls corresponding to a given martian sol date 1s2sol1 This function returns the martian sol date corresponding to input solar logitude Ls eofpb This routine computes a large scale EOF perturbation of a variable surface pressure temperature zonal wind or meridional wind profi_eof This routine adds perturbations along a vertical profile gxrwpb This routine computes a small scale gravity wave perturbation to a variable density temperature zonal wind and meridional wind presO This routine yields high resolution MOLA topography at a given location and recompute surface pressure accordingly molareoid This sub
29. in section 6 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 Just as call_mcd heights can work in high resolution i e using high resolution 32 pixels degree MOLA topography and areoid or low resolution i e at GCM horizontal grid resolution of 5 625 x 3 75 mode At GCM resolution topography and areoid are read from the mount ain nc datafile At high resolu tion the MOLA topography file mola32 nc and spherical harmonics expansion coefficients in file mgm1025 are used All these files are stored in the data directory of the DVD TWe recomend using the same symbolic link stategy as given in section 4 2 40 12 1 Arguments of heights subroutine A Fortran call to the height s subroutine should be as follows call heights dset xlat xlon hireskey convkey amp zradius zareoid zsurface ier where input and output arguments are e dset character x 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
30. ion used to create the data files dust is highly variable on Mars from year to year The Mars Year 24 MY24 scenario was designed to mimic Mars as ob served by Mars Global Surveyor in from 1999 to june 2001 a martian year though to be typical The warm and cold scenario are provided to bracket the possible dust con tent of the atmosphere outside global dust storms dust storm 7 4 represents Mars during a global dust storm dust opacity set to 4 Only available when such storms are likely to happen during northern fall and winter Ls 180 360 Please see the Detailed Design Document for further information perturkey integer Flag to set the type of perturbation to add None Add large scale perturbations using EOFs Add small scale perturbations gravity waves Add small and large scale perturbations 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 same correlated perturbed atmosphere 22 seedin gwlength extvarkey Table 1 CALL_MCD Input arguments continued real integer e if perturkey 1 2 3 or 4 Random number generator seed and flag For the first call to call_mcd this value in fact its in teger part is us
31. key 2 or 4 to simulate a trajectory the value of seedin should be kept constant in order to work with the same correlated perturbed atmo sphere Reseting the large scale perturbations by modifying the value of seedin between calls to cal 1_mcd to build profiles at a given location should only be done in the context of generating a range of different possibilities an example is given in ta ble 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 horizon tal 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 corre lation of the perturbations Note for specialists It has been made possible to keep a given large scale per turbation whilst only changing the gravity wave small scale perturbation between calls This is achieved by changing the value of input argument gwlength be tween 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 spaci
32. local surface m xz is the pressure level Pa xz is the altitude above reference radius 3 396 10 m m N B The zero elevation 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 eo n hi ee integer Flag to set the a at which U 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 20 datekey Table 1 CALL_MCD Input arguments continued integer double precision REAL 8 character string dim 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 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 e if datekey 0 the Julian date e if datekey l1 the solar longitude Ls in degrees Ls 0 360 N B
33. ls_mcd_sci obtained by compiling Fortran source code profils_mcd_sci F can be used to retreive a vertical profileof atmo spheric 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 mcdplot sci 37 10 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 atmemcd and julian from C test_emcd c and C test_emcd cpp main programs Unfortunately inter language calling conventions vary with compilers and op erating systems although the C and C interfaces have been tested on our Linux systems using Gnu compilers g77 gcc g as well as Portland Group compil ers pgf77 pgcc 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 SET o juilavans E gt 77 c heig
34. m 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 level of the database density and pressure are estimated by inte gration of the hydrostatic equation assuming a constant temperature 15 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 e Small scale perturbations due to the upward propagation of gravity waves for any altitudes there is no small scale perturbation for surface pressure e 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 e 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 comprehen sive explanation of the perturbations is included in the Detailed Design Document 3Tn summary the perturbations are calculated as follow e The gravity
35. mol mol Table 6 Variables stored in database mean data files thermosphere Day to day variabilities RMS ARMS RMS Pressure wise and or altitude wise symbol symbol Surface temperature rmstsurf Surface pressure CO ice cover Dust optical depth rmsps rmsco2ice rmsdod Atmospheric temperature armstemp rmstemp Atmospheric density armsrho rmsrho Zonal East West wind armsu rmsu Meridional North South wind armsv rmsv Vertical down up wind armw rmsw Atmospheric pressure armspressure Table 7 Variables stored in database standard deviation data files lower atmo sphere For 3 D variables the arms prefix indicates an altitude wise RMS and the rms prefix a pressure wise RMS 44 Day to cae variabilities Cease ARMS units 2 D Preswrewine mdan sinde wise smol mmol or3 D RET temperature armstemp Atmospheric density armsrho Zonal East West wind armsu Meridional North South wind armsv Vertical down up wind armsw Atmospheric pressure armspressure Table 8 Variables stored in database standard deviation data files thermosphere For 3 D variables the arms prefix indicates an altitude wise RMS and the rms prefix a pressure wise RMS NetCDF library Some general documentation on NetCDF is available on the web athttp www unidata ucar edu packages netcdf docs html Within the call_mcd F heights F or pres0 F source files we also supply several Fortran subroutines For mos
36. n 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 soft ware calculates heights accurately by integrating the hydrostatic equation directly on the hybrid coordinates 14 6 Using the CALL_MCD subroutine 6 1 What is the CALL_MCD subroutine The purpose of the call_mcd subroutine is to extract and compute meteorolog ical variables useful 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 thermal 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 O CO volume mixing ratio e Water vapour and water ice content e Dust aerosol content e Ozone O3 content e Air viscosity heat capacity and Cp C ratio The Fortran subroutine call _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 fro
37. ng and gravity waves re seeding It is meant for experienced users and not advised for general use 6 5 2 Running time In order to minimize computational time the datasets corresponding to encompass ing months of sought input date are read and 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 32 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 RQ RY QB RR Rr RI perturk seedin zkey 3 do i l xz i ey 4 100 seed perturbations work in altitude above local surface coordinate 100 1 2000 0 go from surface to 200km call_mcd zkey xz xlon xlat hireskey profi enddo datekey xdate localtime dset scena perturkey seedin gwlength extvarkey pres dens temp zonwind merwind meanvar extvar seedout ier le 1 1i dens store density some code here moved on to a different time or place far from previous one such that perturbations should be reset seedin seedout change seedin to regenerate perturbations build the new density profile do i 1 100 xZ 1 1 2000 0 go from surface to 200km call_mcd zkey xz xlon xlat hireskey datekey xdate localtime dset scena perturkey seedin gwl
38. ns under Windows you have 2 solutions 1 Install a Unix environment emulator for Windows The most popular is Cyg win which you can download from http www cygwin com This emulator includes most Unix features and softwares NetCDF libraries can be built on Cygwin as easely as on other Unix systems As far as a few tests 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 2 Port the Mars Climate Database to Windows We have not fully tested that possibility but several users have done so successfully NetCDF li brairies 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 18 directory described in section 4 2 will not work the true path to that direc tory must be used in the Fortran routines and programs see variable dset in the description of cal l_mcd arguments in section 6 4 6 4 CALL_MCD input and output arguments A Fortran call to subroutine call_mcd should look something like call_mcd zkey xz xlon xlat hireskey datekey xdate localtime dset scena perturkey seedin gwlength extvarkey pres dens temp zonwind merwin
39. orking 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 For instance if one wishes to access the data directly from the DVD ROM If the DVD ROM is mounted as dev dvdrom then create the link ln s dev dvdrom data MCD_DATA N B In the call_mcd subroutine the path to the directory can be given as an input using the dset argument e g dset dev cdrom data gt This symbolic link strategy unfortunately does not work with Windows where the full path to the data directory must be used 12 although by default the subroutine will use MCD_DATA if dset is not ini tialized or set to 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 Question 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 net cdf inc and a Fortran library file named 1ibnetcdf a The version of the files depends of the machine and of the compiler An easy way to get them is
40. perturbed 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 N B Close to the surface i e below the lowest MCD level which is around 4 5 m above the ground and down to the aerodynamic roughness length of 1 cm the horizontal winds fall logarithmically to zero following classical boundary layer theory If you want near surface winds then sample at a range of non zero heights close to the surface as appropriate for your application 24 extvar Table 2 CALL_MCD output arguments continued real dim 100 Supplementary variables array extvar 1 to extvar 7 provides time and space coordinate which are always computed and are therefore always set extvar 8 to extvar 50 are only computed and set if input argument extvarkey 1 These are otherwise set to zero The rest of the array extvar 51 to extvar 100 is unused yet and always set to zero These supplementary variables are usually not used for atmo spheric trajectory computations but are useful for environmental studies extvar 1 Radial distance to planet center m extvar 2 Altitude above areoid Mars geoid m 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 respe
41. rbation i e n 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 16 6 2 Software Package The call_mcd subroutine is in directory mcd This directory includes e README a short text file which summarizes the information contained here e File call_mcd F which contains the CALL MCD main subroutine and most of the subroutines and functions it calls e the include file constants_mcd inc used by call_mcd and subsidiary routines e File test_mcd F which contains a simple and straightforward illustration of a program using call mcd and julian e The compile file which contains an example of the Unix command line to compile the subroutine and program e The file test_mcd def contains a list of input data for test_mcd see section 6 3 e A subdirectory testcase containing test cases used to test the accuracy of your installation of the database e the julian F file which contains a subroutine which computes the Julian date corresponding to a given calendar date e the heights F file which contains the subroutines necessary to convert distances
42. rdinates may be specified as input The data sets of version 4 3 are similar to those of the previous version exept for the files which contain informa tion for large scale perturbation reconstruction which have been updated As of version 4 2 the major improvement is in the MCD access software the Fortran routine call_mcd which now include a high resolution mode via postprocessing 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 presO 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 Comparisons of MCD outputs with available measurements are addressed in the Validation Document Contents 1 Introduction Lal Available Data 2 aos acne el eo ea a a le A a 1 2 Database scenarios 0 00000002 eee 1 3 Highresolutionmode 04 Differences Between Version 4 3 and Previous Versions of the MCD Contents of the
43. rite tools with the Fortran subroutine call_mcd in corresponding subdirectories see sections 7 to 10 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 the most flexibility for particular applications e g when one wants to handle global fields although it does demand a greater understanding of how the database contents are organised see appendix A as well as of how the variability models if these are required should 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 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 Ferret 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 ncview or ncBrowse 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 o
44. rom state of the art General Circulation Model GCM simulations of the Martian atmosphere Forget et al 1999 The models used to compile the statis tics have been extensively validated using available observational data and repre sent 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 Minor enhancements and additions may be performed after the delivery of this version of the database Such changes are given in the README file available on line at http www 1md jussieu fr forget dvd where the up to date contents of DVD is always available The MCD can also be accessed in a variety of data formats using our interactive Live Access Sever from our WWW site at http www mars ilmd 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 turbulent kinetic energy 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 longitude Ls and is typically 50 70 days long In other words at every grid point the databa
45. routine returns the radial position ie distance to the center of Mars of the reference areoid for a given location 47
46. se 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 Could not open a database file i1e but found that a cor responding gzipped file gz version of the file exists You should got to the dset directory and de compress it e g gunzip file gz on Unix systems 6 5 The right use of the CALL_MCD subroutine 6 5 1 Perturbed atmospheres The perturbation consisting of adding n times 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 underesti mate the profiles of the meteorological variables To generate randomly perturbed atmospheres you must use small or large scale perturbations which take into ac count some correlation of perturbations in the space and between variables Then 31 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 per turbations pbertur
47. se 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 6 1 1 2 Database scenarios Eight combinations of dust and solar scenarios have been used 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 max imum average and or minimum conditions are provided e On the other hand the major factor which governs the variability in the Mar tian 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 distribu tion and optical properties can be uncertain multi annual model integrations were carried out for the database assuming various dust scenarios i e pre scribing various amount of airborne dust in the simulated atmosphere 4 dust scenarios are proposed 1 The Mars Year 24 MY24 scenario was designed to mimic Mars as observed by Mars Global Surveyor from 1999 to june 2001 a martian year thought to be representative of one without a global dust storm The dust fields were derived
48. t applications using the call_mcd subrou tine should be good enough to access the database but if you want to process to the global fields it may sometimes be easier to use NetCDF A 2 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 netcdf inc integer unet NetCDF file unit number integer ierr character 256 datfile NetCDF data file datfile FULL PATH NAME mcd data MY24_04_me nc ierr NF_OPEN datfile NF_NOWRITE unet 45 read some NetCDF data ierr NF_CLOSE unet close the file A 2 2 Manipulating Data Once the file has been opened you can read data from the MCD either by using the NetCDF routines directly or by using subroutines from the mcd directory The following routines may prove particularly useful They can be found in the main call_mcd 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 e loadvar must be called to load the needed database arrays e loadeof must be called to load EOF data for the large scale perturbation model e var2d retrieves the value of a 2 D field at a given location and time Uses bilinear interpolation from the database grid points values in longitude and latitude and linear interpolation in t
49. to go to the unidata netcdf web page click on precompiled binaries download a compressed file cor responding 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 com piling applications see the compile files in the database Unfortunately this does not always work if your compiler doesn t work with the precom piled library you will have to recompile Netcdf with it and follow the web site instructions 5 Ways to access the database There are three main ways of accessing data from the MCD which have been im plemented 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 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 with particular 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 13 Secondly users who prefer using IDL Matlab or Scilab software or who program in C and or C will find examples of how to interface their favo
50. wave perturbation of a meteorological variable is calculated by considering vertical displacements of the form 6z h sin 40 1 where A is a characteristic vertical wavelength for the gravity wave and o is a randomly generated surface phase angle surface angle dz 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 e 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 of the database e For the last type of pertu
51. 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 contain data about dust storm sceanarios i e files in the data directory 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 com pared to its predecessor atmemcd have been introduced Anew high resolution procedure based on the integration of high resolution 32 pixels per degree MOLA topography has been im plemented Input and output arguments which are floating numbers are now declared as single precision i e Fortran REAL except xdate which is double precision i e Fortran REAL 8 The way by which users impose date and local time has changed Input longitude and latitude must now be given in degrees Longitude is
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