 |
| Titel |
Multi-Instrument and Modelling Study of Small-Scale Upwelling and Density Changes in the Auroral Thermosphere-Ionosphere Region |
| VerfasserIn |
Anasuya Aruliah, David Johnson, Amy Ronksley, Herbert Carlson |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250113249
|
| Publikation (Nr.) |
 EGU/EGU2015-13447.pdf |
|
|
|
|
|
| Zusammenfassung |
| An unexpected persistent thermospheric density enhancement over the magnetic cusp was
observed by the CHAMP satellite in low-Earth orbit at 400km. The density enhancement is
caused by denser air from below being lifted into the increasingly rarefied air above. In
contrast, the Streak satellite (in a highly elliptical orbit) showed density depletions of the
thermospheric cusp at 250km altitude. Several heating mechanisms have been proposed
which include auroral particle precipitation and Joule heating. Conventional modelling
simulations required over a 100 times the typical measured values of ion-frictional heating in
the cusp. Other model simulations could not provide a large enough density enhancement.
Coordinated Fabry-Perot Interferometer and EISCAT radar observations are presented which
show large vertical winds consistent with the density enhancements. The UCL
Coupled Middle Atmosphere Thermosphere model (CMAT2) model is used to
test various mechanisms. It is proposed that in-situ measurements of small-scale
structures can be provided by the multi-cubesat mission QB50, due for launch in
2016.
The cusp upwelling is a persistent feature that does not appear in existing Global
Circulation Models because it is below typical spatial resolution, but will have a systematic
influence on satellite orbits and ionospheric signal propagation. |
|
|
|
|
|
|