 |
| Titel |
Morphological features and variations of temperature in the upper thermosphere simulated by a whole atmosphere GCM |
| VerfasserIn |
H. Fujiwara, Y. Miyoshi |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 28, no. 2 ; Nr. 28, no. 2 (2010-02-08), S.427-437 |
| Datensatznummer |
250016774
|
| Publikation (Nr.) |
 copernicus.org/angeo-28-427-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| In order to illustrate morphological features and variations of temperature
in the upper thermosphere, we performed numerical simulations with a whole
atmosphere general circulation model (GCM) for the solar minimum and
geomagnetically quiet conditions in March, June, September, and December. In
previous GCMs, tidal effects were imposed at the lower boundaries assuming
dominant diurnal and semi-diurnal tidal modes. Since the GCM used in the
present study covers all the atmospheric regions, the atmospheric tides with
various modes are generated within the GCM. The global temperature
distributions obtained from the GCM are in agreement with ones obtained from
NRLMSISE-00. In addition, the GCM also represents localised temperature
structures which are superimposed on the global day-night distributions.
These localised structures, which vary from hour to hour, would be observed
as variations with periods of about 2–3 h at a single site. The
amplitudes of the 2–3 h variations are significant at high-latitude,
while the amplitudes are small at low-latitude. The diurnal temperature
variation is more clearly identified at low-latitude than at high-latitude.
When we assume the same high-latitude convection electric field in each
month, the temperature calculated in the polar cap region shows diurnal
variation more clearly in winter than in summer. The midnight temperature
maximum (MTM), which is one of the typical low-latitude temperature
structures, is also seen in the GCM results. The MTMs in the GCM results
show significant day-to-day variation with amplitudes of several 10s to
about 150 K. The wind convergence and stream of warm air are found around
the MTM. The GCM also represent the meridional wind reversals and/or
abatements which are caused due to local time variations of airflow pattern
in the low-latitude region. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|