Earth Global Reference Atmospheric Model (GRAM) Overview and Modern Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) Global Atmosphere Upgrade

NASA Marshall Space Flight Center’s (MSFC) Earth Global Reference Atmospheric Model (GRAM) is a reference or standard atmosphere used for design and mission planning of various aerospace systems. Earth-GRAM was developed in response to the need for a design reference atmosphere that provides complete global geographical variability, complete altitude coverage (surface to orbital altitudes), and complete seasonal and monthly variability of thermodynamic variables and wind components. A unique feature of Earth-GRAM is that, in addition to providing the geographical, height, and monthly variation of the mean atmospheric state, it includes the ability to simulate spatial and temporal perturbations in these atmospheric parameters. The GRAM team plans to release an updated version of Earth-GRAM including the MERRA-2 global atmosphere upgrade, by Fall of 2023. The paper will describe an overview of Earth-GRAM, discuss the MERRA-2 upgrade, and discuss future upgrades of Earth-GRAM.