Earth Global Reference Atmospheric Model (Earth-GRAM 2010)

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Ionosphere and Thermosphere (solar and Thermal Environment) 



Global model, using empirical database, giving density, temperature, pressure, winds, and selected atmospheric constituent concentrations, from the surface of the Earth to orbital altitudes, as a function of geographic position and time of year. Local perturbations about mean conditions are also included. Model is also suitable for use as a subroutine in a trajectory code or orbit propagator program or other programs used for simulations of in-flight or on-orbit atmospheric variability in density, temperature, or winds.


New Features of GRAM 2010 -

1.     Updated the lower atmosphere database – Replaced Global Upper Air Climatic Atlas (GUACA) climatology with monthly global climatology (means and standard deviations) from National Centers for Environmental Prediction (NCEP) Reanalysis Project.  This database is now provided with the GRAM2010 software package.  The default NCEP period of record is 1990-2008 and includes means and standard deviations for four times of day (00UT, 06UT, 12UT, and 18UT).  Thus the user now has the option of selecting the monthly average at these specific times of day.


2.     Revised boundary layer model –Added effects of time-of-day and atmospheric stability on boundary layer height and vertical wind standard deviations in the boundary layer.


3.     Updated thermosphere models – Replaced JB2006 thermosphere model with new JB2008.  Used global climatology of chemical release winds to revise wind perturbation standard deviations in the 90-120 km altitude range.


4.     Converted code to double precision Fortran 90 – Also converted all common blocks to modules, with consistent variable names.  Added interface modules.   Changed identifiers on subroutines, functions, etc. from _E07 to _E10.  Added _E10 suffixes to all subroutine and function names in the three thermosphere models.  Added  _e10 suffix to header line of namelist input file ($namein_e10).s. 


5.     New scaling parameter for standard deviations – The user now has the option of independently increasing the standard deviations of the horizontal wind, the vertical wind, and the thermodynamic variables (density, temperature, and pressure). 


6.     New Range Reference Atmosphere (RRA) input parameter – User has the option to provide a file name for list of available sites.  Different RRA sites or combinations of sites can be made available by building various RRA lists, and the RRA set to use controlled at run time. 


7.     New option for auxiliary profiles – Added option to input standard deviations (sigmas) in auxiliary profiles.  If zero values are entered, sigmas are taken from conventional climatology.  An exception to this is for isolated zero values for sigmas, which are set the same as the previous (non-zero) sigma.


8.     Moisture corrections – Revised use of Elliott-Gaffen moisture corrections, to take advantage of all moisture variables available in the of NCEP data.  Revised calculation of standard deviation of relative humidity (RH), to account for correlation between vapor pressure and saturation vapor pressure (correlation evaluated empirically from study of NCEP RH data). 


9.     Additional output parameters – Added mean sound speed and perturbed sound speed to "print format" and "special format" output files.  Added output of wind speed means and standard deviations, and cross correlation between Eastward and Northward wind components (Ruv).  Ruv is used to compute the wave-like large-scale northward wind perturbation in such a way as to produce the appropriate degree of cross-correlation.


Additional Information:

Language: FORTRAN 90

Operating System: PC/DOS, Unix

Hardware Requirements: Runs on PC (or compatible) and on most Unix hardware.  Need at least 2 GIG of storage space.


  • Maintenance/ Upgrades: On an as needed basis
  • Source Code: Source code is available
  • Cost: Program: No cost to qualified, NASA approved users
  • Distribution: Available upon request at
  • Manuals: Yes
  • Training: No

Input Description: Geographic position, time, NCEP data (provided),  solar and geo-magnetic data (for heights above 90 km)

Output Format: Density, temperature, pressure, winds, and selected atmospheric constituent concentrations, from the surface of the Earth to orbital altitudes.

Verification/ Validation: Model is based on empirical data and validated against other empirical data and previous models.


Point of Contact:

Patrick White
NASA Marshall Space Flight Center
MSFC, AL  35812
Phone: (256) 961-7942

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