A model of high‐latitude thermospheric density

Yosuke Yamazaki,Michael J Kosch,Eric K Sutton

doi:10.1002/2015ja021371

Yosuke Yamazaki, Michael J Kosch + Show 1 more

Open Access

https://doi.org/10.1002/2015ja021371

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Abstract

AbstractWe present an empirical model of the high‐latitude air density at 450 km, derived from accelerometer measurements by the CHAllenging Minisatellite Payload and Gravity Recovery and Climate Experiment satellites during 2002–2006, which we call HANDY (High‐Latitude Atmospheric Neutral DensitY). HANDY consists of a quiet model and disturbance model. The quiet model represents the background thermospheric density for “zero geomagnetic activity” conditions. The disturbance model represents the response of the thermospheric density to solar wind forcing at high latitudes. The solar wind inputs used are the following: (1) solar wind electric field ESW, (2) interplanetary magnetic field (IMF) clock angle CSW, and (3) solar wind dynamic pressure PSW. Both quiet and disturbance models are constructed on the basis of spherical harmonic function fitting to the data. Magnetic coordinates are used for the disturbance model, while geographical coordinates are used for the quiet model. HANDY reproduces main features of the solar wind influence on the high‐latitude thermospheric density, such as the IMF By effect that produces a hemispheric asymmetry in the density distribution.

Highlights

The magnetosphere-ionosphere-thermosphere system is under significant influence of the solar wind at high latitudes
We present an empirical model of the high-latitude air density at 450 km, derived from accelerometer measurements by the CHAllenging Minisatellite Payload and Gravity Recovery and Climate Experiment satellites during 2002–2006, which we call HANDY (High-Latitude Atmospheric Neutral DensitY)
The larger error for Mass Spectrometer Incoherent Scatter Radar Extended (MSISE)-00 than HANDY is partly due to the fact that MSISE-00 does not include CHAllenging Minisatellite Payload (CHAMP)/Gravity Recovery and Climate Experiment (GRACE) data in fitting while HANDY does

Summary

Introduction

The magnetosphere-ionosphere-thermosphere system is under significant influence of the solar wind at high latitudes. The following are examples: Mass Spectrometer Incoherent Scatter Radar Extended (MSISE) models [Hedin, 1991; Picone et al, 2002]; Drag Temperature Model [Bruinsma et al, 2003, 2012]; Jacchia-Bowman (JB) models [Bowman et al, 2008a, 2008b]; and CHAllenging Minisatellite Payload (CHAMP) empirical model [Liu et al, 2013] Those models evaluate the air density as a function of altitude, latitude, longitude, solar time, solar and geomagnetic activities, and day of year. The three-dimensional models mentioned above do not include high-latitude density features This issue was brought to light when Liu et al [2005] compared thermospheric densities measured by the CHAllenging Minisatellite Payload (CHAMP) satellite [Reigber et al, 2002] with the MSISE-90 model [Hedin, 1991]. The model results are discussed in comparison with previous results in the literature

Data and Model Construction

Model Results and Discussion

Dependence on Solar Wind Drivers