Modeling the thermosphere as a driven-dissipative thermodynamic system

Abstract

Thermospheric density impacts satellite position and lifetime through atmospheric drag.More accurate specification of thermospheric temperature, a key input to current models such as the High Accuracy Satellite Drag Model, can decrease model density errors. This paper improves the model of Burke et al. (2009) to model thermospheric temperatures using the magnetospheric convective electric field as a driver. In better alignment with Air Force satellite tracking operations, we model the arithmetic mean temperature, T 1/2 , defined by the Jacchia (1977) model as the mean of the daytime maximum and nighttime minimum exospheric temperatures occurring in opposite hemispheres at a given time, instead of the exospheric temperature used by Burke et al. (2009). Two methods of treating the solar ultraviolet (UV) contribution to T 1/2 are tested. Two model parameters, the coupling and relaxation constants, are optimized for 38 storms from 2002 to 2008. Observed T 1/2 values are derived from densities and heights measured by the Gravity Recovery and Climate Experiment satellite. The coupling and relaxation constants were found to vary over the solar cycle and are fit as functions of F 10.7a , the 162 day average of the F 10.7 index. Model results show that allowing temporal UV variation decreased model T 1/2 errors for storms with decreasing UV over the storm period but increased T 1/2 errors for storms with increasing UV. Model accuracy was found to be improved by separating storms by type (coronal mass ejection or co-rotating interaction region). The model parameter fits established will be useful for improving satellite drag forecasts.

Thermospheric mass density: A review

“…They found that in the weaker events, the contributions of Joule heating and EPP are roughly equal, whereas in strong events, Joule heating dominates. Several papers (Burke et al, 2009(Burke et al, , 2010Burke, 2011;Frey et al, 2014) have studied the density response to solar wind variations by treating the thermosphere empirically as a dissipative system, using exospheric temperature inferred from accelerometer measurements. Weimer et al (2011) related Poynting flux derived from interplanetary magnetic field (IMF) measurements to exospheric temperature derived from CHAMP and GRACE, for possible use as a geomagnetic activity argument in empirical models.…”

“…They proposed that the latter component could be used as a proxy for the response of the thermosphere to geomagnetic activity forcing. Several papers (Burke et al, 2009(Burke et al, , 2010Burke, 2011;Frey et al, 2014) have examined the density response to solar wind variations by treating the thermosphere empirically as a dissipative system, using exospheric temperature inferred from accelerometer measurements. Bhatnagar et al (2005) examined storm-induced variations in orbit-derived density near 200 km altitude during 2001.…”

Investigating Upper Atmospheric Joule Heating Using Cross‐Combination of Data for Two Moderate Substorm Cases

“…Bussy‐Virat et al () reports that the largest source of errors for LEO satellite orbit determination comes from the thermospheric neutral density, which is largely enhanced by the JH during the geomagnetic storms (Zesta & Huang, ). JH causes the upwelling of the neutrals in the thermosphere resulting in the enhanced atmospheric drag on the satellites, thus becomes one of the main contributors in the drag force through the variations in thermospheric neutral density (Fedrizzi et al, ; Frey et al, ). Larger atmospheric drag reduces the life time of the satellites and increases orbit prediction errors and the probability of collisions between the objects existing in the LEO (Prölss, ; Zesta & Huang, ).…”