Trace constituent updates in the Marshall engineering thermosphere and global reference atmospheric model

This report examines GRAM/MET constituents between 100 and 1000 km altitudes. Internal discrepancies are noted between GRAM/MET constituent number densities and mass density or molecular weight. Near 110 km altitude, there is up to about 25% discrepancy between MET number density and mass density (with mass density being valid and number densities requiring adjustment). Near 700 km altitude there is also up to about 25% discrepancy between MET number density and mean molecular weight (with molecular weight requiring adjustment). In neither case are MET mass density estimates invalidated. The discrepancies have been traced to MET subroutines SLV (which affects 90-170 km height range) and SLVH (which affects helium above 440 km altitude). With these discrepancies corrected, results are presented to illustrate GRAM/MET constituent mole fractions in terms of height-latitude cross-sections from 100 to 1000 km altitude, and latitude-longitude “maps” at 450 km. Plans are discussed for an update of MET and GRAM to correct these constituent inconsistencies, and to incorporate several new thermospheric model features.