Prototype Whole Atmosphere Global Numerical Weather Prediction System Based on a 0-500 km Extension of the Navy Global Environmental Model (NAVGEM)

NAVGEM is the Navy’s operational global numerical weather prediction (NWP) system with a current upper boundary at ~70 km altitude. We describe a new research configuration that leverages this operational NWP system but extends the capability to an exobase altitude of ~500 km. Novel scientific features include an augmented dynamical core and time integration method for the two-time-level semi-implicit semi-Lagrangian forecast model to accommodate hot thermospheres of variable composition, and a new data assimilation algorithm based on the Local Ensemble Transform Kalman Filter (LETKF). The system is then readied for real-world NWP tests via inclusion of a new mesospheric and thermospheric physics suite that includes ionospheric, geomagnetic and solar drivers, and new routines to assimilate wind and temperature measurements from the mesosphere and thermosphere. Examples of “whole atmosphere” forecasts and data assimilation products from this prototype system will be presented for selected periods in 2020-2022 when thermospheric observations from NASA’s Ionospheric Connection Explorer (ICON) were available for both assimilation and verification.

Acknowledgments: This work was supported by the Office of Naval Research, and the DARPA Defense Sciences Office under the Space Environment Exploitation (SEE) program.