The NASA MSFC Earth Global Reference Atmospheric Model—2007 Version

The latest version of the Earth Global Reference Atmospheric Model (Earth-GRAM2007) is presented and discussed. Earth-GRAM2007 uses either (binary) Global Upper Air Climatic Atlas (GUACA) or (ASCII) Global Gridded Upper Air Statistics (GGUAS) CD-ROM data sets, for 0-27 km altitudes. As with earlier versions, Earth-GRAM2007 provides complete geographical and altitude coverage for each month of the year. Earth-GRAM2007 uses a specially-developed data set, based on Middle Atmosphere Program (MAP) data, for 20-120 km altitudes, and NASA’s 1999 version Marshall Engineering Thermosphere (MET-99) model for heights above 90 km. Fairing techniques ensure smooth transition in overlap height ranges (20-27 km and 90-120 km). Earth-GRAM2007 includes water vapor and 11 other atmospheric constituents (O3, N2O, CO, CH4, CO2, N2, O2, O, A, He, and H). A variable-scale perturbation model provides both large-scale (wave) and small-scale (stochastic) deviations from mean values for thermodynamic variables and horizontal and vertical wind components. The small-scale perturbation model includes improvements in representing intermittency (“patchiness”). A major feature is an option to substitute Range Reference Atmosphere (RRA) data for conventional GRAM climatology when a trajectory passes sufficiently near any RRA site. A complete user’s guide for running the program, plus sample input and output, is provided. An example is provided for how to incorporate Earth-GRAM2007 as subroutines in other programs (e.g. trajectory codes).