Comparisons of the NRL SAMI3 Physics-Based Ionospheric Model with Global Ionosonde and GPS Electron Density Measurements

Abstract:

The Naval Research Laboratory is conducting an interdisciplinary physics-based Space Weather model development and validation program called the Integrated Sun-Earth System for the Operational Environment (ISES-OE). In contrast to other geospace integration efforts, a key aspect of ISES is determining the extent to which current models capture the climate of the ionosphere and thermosphere. Until now, complementary long-term simulations using physics-based ionosphere models have not been performed. As part of this program, numerous runs of the physics-based SAMI3 model have been made and compared to global measurements of electron density. The data sets includes: 1) Ionosonde NmF2 and hmF2 measurements, 2) GPS Total Electron Content (TEC) measurements and others. This presentation compares electron density data with SAMI3 and other models during much of Solar Cycle 23 and the ascending phase of Cycle 24.

Previous work has concentrated on the Whole Heliospheric Interval (WHI) from February 19 - April 19, 2008 [Lean et al., 2014]. This solar minimum period with extremely low solar activity was used to test the validity of the SAMI3 simulations of the base-state ionosphere. Several modifications to SAMI3 were incorporated including updates to the Solar EUV fluxes, the NRL MSIS neutral atmospheric model parameterization at Solar Minimum and compensating for variations in the Sun-to-Earth distance. Data and model comparisons during times of higher solar activity will be presented with an emphasis on understanding the effects of coupling of the neutral atmosphere, neutral winds and driving electric fields on our ability to model the measured global electron density data. We examine responses to solar EUV radiation and geomagnetic activity, and semiannual and annual oscillations that all induce geospace variability.

Lean, J. L., S. E. McDonald, J. D. Huba, J. T. Emmert, D. P. Drob, and C. L. Siefring (2014), Geospace variability during the 2008–2009 Whole Heliosphere Intervals, J. Geophys. Res. Space Physics, 119, 3755–3776, doi:10.1002/2013JA019485.

This work supported by the Naval Research Laboratory Base Program.