Study of the F3 and StF4 layers formation and the TEC near the southern crest of the EIA at the low latitude region in the Brazilian sector
Abstract
The study of F-layer multiple stratifications received a great attention after the StF4 observations at Palmas, Brazil (dip 6.6°S) a near-equatorial region. This investigation presents the seasonal and solar cycle variations of the daytime F-layer multiple stratification (F3 and StF4 layers) and the variations of the TEC near the southern crest of the EIA in the eastern South American sector. The ionograms recorded by a CADI digital ionosonde installed at Sao Jose dos Campos (23.2°S, 45.9°W; dip latitude 17.6°S, eastern sector-hereafter referred as SJC), Brazil, from 2002 to 2010. Among the main results, we can highlight that the F3 layer occurrence shows an annual variation with maximum during pre-summer/summer time and minimum during winter time. Compared to the pre-summer and summer times, there are a higher F3 layer occurrence during pre-summer time than summertime. Concerning the StF4 occurrence at SJC, the results have shown a maximum during summertime, and no occurrence during wintertime. A total of 1431 days were analyzed and the results shown that the F3 layer was found in 376 days (26,3%), while the StF4 layer was found in 5 days (0.3%), indicating that the StF4 is seen during 1.3% of F3 layer days. The F3 and StF4 layers occurrence do not show a clear solar activity dependence. Furthermore, a significant connection between StF4 and F3 has been noticed in both stations, since the StF4 layer is always preceded and followed by a F3 layer appearance. It will be presented and discussed the behavior of the local TEC during the period considered and the role of the gravity waves in the F3 layer formation over SJC (low latitude region).
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSA51B3151T
- Keywords:
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- 2415 Equatorial ionosphere;
- IONOSPHERE;
- 2431 Ionosphere/magnetosphere interactions;
- IONOSPHERE;
- 6969 Remote sensing;
- RADIO SCIENCE;
- 7944 Ionospheric effects on radio waves;
- SPACE WEATHER