Do Lower Atmospheric Drivers Improve Ionospheric Forecasting?

Abstract:

The Sun is the primary source of ionization of Earth’s ionosphere, and the influences of both changing solar irradiance and geomagnetic activity are primary components of current models of ionospheric and thermospheric variability. Meteorological influences propagating upward from the lower and middle atmosphere, including the troposphere and stratosphere, constitute the largest component of unexplained variability in the thermosphere/ionosphere region. Recently, coupled atmosphere-ionosphere models have demonstrated the importance of including lower atmospheric forcing in order to simulate day-to-day and longitudinal variability in the ionosphere. For example, nonmigrating tides of tropospheric origin modulate the longitudinal structure of the low-latitude ionosphere, and tidal variability in the mesosphere-lower-thermosphere region during sudden stratospheric warming events leads to variations in the ionosphere on timescales of days to weeks. It is not yet known to what extent the inclusion of forcing from below as well as from above increases ionospheric forecast skill. In this talk we use NRL’s physics-based 3D ionosphere model, SAMI3, coupled with the Whole Atmosphere Community Climate Model eXtended (WACCM-X) to examine whether forecasts of the lower atmosphere improve forecasts of the ionosphere. Lower atmospheric weather forecasts of the prototype Navy Global Environmental Model for High-Altitude (NAVGEM-HA) constrain WACCM-X below 90 km. We compare the SAMI3/WACCM-X ionospheric forecasts with those of NRLTEC, a new statistical forecast model of global and regional total electron content based on IGS TEC 2-hour global ionosphere maps that does not include the effects of the lower atmosphere. The 5-day forecast skill of NRLTEC exceeds that of persistence and climatology. Both forecast models are compared to observations.