How Empirical Models Continue to be Useful for Space Environment Modeling

Abstract:

Many of the current physics-based models of the ionosphere and ionosphere-thermosphere system require embedded empirical models to drive the physics of physics-based models. How far can the modeling of Ionosphere-Thermosphere-Electric Field system or parts thereof move away from empirical models? How far should the community continue to make improvements to the empirical models of the space environment?

Examples of useful empirical models are the Oval Variation, Assessment, Tracking, Intensity, and Online Nowcasting (OVATION) [Newell et al., 2010] and Hardy Oval [Hardy et al., 1987] precipitation, Weimer convection potential [Weimer et al., 2005], Horizontal Wind Model (HWM) [Drob et al., 2015], quiet time low latitude plasma drifts [Scherliess and Fejer, 1999], etc. What should be improved? What should be replaced with physics-based modeling?

We explore these questions and indicate how the usefulness of empirical models of the space environment can be advanced.

1. Empirical models should capture the observations accurately and can be used to benchmark physics-based couple models that attempt to replace empirical models. This requires that key empirical models should become International Reference models under the direction of interested experts. The participants can direct improvements in the observation database being represented and improvements in the availability of the empirical model for computation usefulness, that is, publicly available in modern and traditional languages (Python, C, Fortran).
2. Empirical models can be examined in their consistency with other empirical models. For example, do the empirical representations of high-latitude precipitation, convection electric field, and Poynting Flux present a consistent picture of the high-latitude drivers or do their inconsistencies present physics-based models with problematic drivers. A second example, is there consistency between empirical neutral winds and empirical plasma drifts arising from the neutral wind dynamo. In other words, does the Horizontal Wind Model within an ionosphere-electric field model generate Scherliess/Fejer empirical plasma drifts?

Drob, D. P. et al. (2015). An update to the Horizontal Wind Model (HWM): The quiet time thermosphere, Earth Space Sci., 2, 301-319, doi:10.1002/2014EA000089.

Hardy, D. A., M. S. Gussenhoven, R. Raistrick, and W. J. McNeil (1987). Statistical and Functional Representations of the pattern of auroral energy flux, number flux, and conductivity, J. Geophys. Res., doi.org/10.1029/ja092ia11p12275.

Newell, P.T., T. Sotirelis, and S. Wing (2010), Seasonal variations in diffuse, monoenergetic, and broadband aurora, J. Geophys. Res., 115, A03216, doi:10.1029/2009JA014805.

Scherliess, L. and B. G. Fejer (1999). Radar and satellite global equatorial F region vertical drift model, J. Geophys. Res., doi.org/10.1029/1999ja900025.

Weimer, D. R., Improved ionospheric electrodynamic models and application to calculating Joule heating rates, Journal of Geophysical Research, 110, A05306, doi:10.1029/2004JA010884, 2005.

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