Seasonal variations of thermospheric mass density at dawn/dusk from GOCE observations
Thermospheric mass densities from the GOCE (Gravity field and steady-state Ocean Circulation Explorer) satellite for Sun-synchronous orbits between 83.5° S and 83.5° N, normalized to 270 km during 2009–2013, have been used to develop an empirical mass density model at dawn/dusk local solar time...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-03-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/36/489/2018/angeo-36-489-2018.pdf |
| Summary: | Thermospheric mass densities from the GOCE (Gravity field and
steady-state Ocean Circulation Explorer) satellite for Sun-synchronous orbits
between 83.5° S and 83.5° N, normalized to 270 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 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. |
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| ISSN: | 0992-7689 1432-0576 |