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| Titel |
Effect of solar cycle on topside ion temperature measured by SROSS C2 and ROCSAT 1 over the Indian equatorial and low latitudes |
| VerfasserIn |
A. Borgohain, P. K. Bhuyan |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 30, no. 12 ; Nr. 30, no. 12 (2012-12-06), S.1645-1654 |
| Datensatznummer |
250017291
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| Publikation (Nr.) |
 copernicus.org/angeo-30-1645-2012.pdf |
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| Zusammenfassung |
| The effect of solar activity on the diurnal, seasonal and latitudinal
variations of ion temperature Ti and its relationship with corresponding ion
density Ni over the Indian low and equatorial topside ionosphere within
17.5° S to 22.5° N magnetic latitudes are being
investigated, combining the data from SROSS C2 and ROCSAT 1 for the 9-year
period from 1995 to 2003 during solar cycle 23. Ti varies between 800 K and
1100 K during nighttime and rises to peak values of ~1800 K
in the post sunrise hours. Daytime Ti varies from 1000 K to 1500 K. The time
of occurrence, magnitude and duration of the morning enhancement show
distinct seasonal bias. For example, in the June solstice, Ti increases to
~1650 K at ~06:00 h and exhibits a daytime
plateau till 17:00 LT. In the equinoxes, enhanced ion temperature is
observed for a longer duration in the morning. There is also a latitudinal
asymmetry in the ion temperature distribution. In the equinoxes, the daytime
Ti is higher at off equatorial latitudes and lower over the Equator, while in
the solstices, Ti exhibits a north–south gradient during daytime. Nighttime
Ti is found to be higher over the Equator. Daytime ion temperature exhibits
insignificant positive correlation with F10.7 cm solar flux, while
nighttime ion temperature decreases with increase in solar flux. Daytime ion
temperature and ion density are negatively correlated during solar minimum,
while nighttime Ti does not exhibit any correlation. However, during high
solar activity, significant positive correlation of Ti with Ni has been
observed over the Equator, while at 10° S and 10° N
temperature and density exhibit significant negative correlation. The
neutral temperature Tn derived from the MSISE 90 model is found to be higher
than measured Ti during nighttime, while daytime Ti is higher than model Tn. |
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