Seasonal variations of thermospheric mass density at dawn/dusk from GOCE observations

Libin Weng, Jiuhou Lei, Eelco Doornbos, Hanxian Fang, Xiankang Dou
2018 Annales Geophysicae  
<p><strong>Abstract.</strong> Thermospheric mass densities from the GOCE (Gravity field and steady-state Ocean Circulation Explorer) satellite for Sun-synchronous orbits between 83.5°<span class="thinspace"></span>S and 83.5°<span class="thinspace"></span>N, normalized to 270<span class="thinspace"></span>km during 2009–2013, have been used to develop an empirical mass density model at dawn/dusk local solar time (LST) sectors based on the empirical orthogonal function (EOF) method. The main
more » ... ethod. The main results of this study are that (1) the dawn densities peak in the polar regions, but the dusk densities maximize in the equatorial regions; (2) the relative seasonal variations to the annual mean have similar patterns across all latitudes regardless of solar activity conditions; (3) the seasonal density variations show obvious hemispheric asymmetry, with large amplitudes in the Southern Hemisphere; (4) both amplitude and phase of the seasonal variations have strong latitudinal and solar activity dependences, with high amplitude for the annual variation at higher latitudes and semiannual variation at lower latitudes; (5) the annual asymmetry and effect of the Sun–Earth distance vary with latitude and solar activity.</p>
doi:10.5194/angeo-36-489-2018 fatcat:usx343vharc4xdjpy52vcf3by4