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- Title
Longitudinal Variations of the Occurrence Probability of the Ionospheric F<sub>1</sub> Layer Peak at Middle and High Latitudes.
- Authors
Li, Zhenxing; Luan, Xiaoli; Ren, Dexin
- Abstract
This study focuses on the longitudinal variations of the ionospheric F1 layer occurrence probabilities from middle to high latitudes (40–70°) in the daytime in summer under low solar activity conditions. The ionospheric electron density profiles retrieved from the Constellation Observing System for Meteorology, Ionosphere, and Climate observations are used. The patterns of the F1 layer occurrence probabilities are constructed with latitude, longitude, and local time in both hemispheres. The results illustrate a new feature that the occurrence probability of the F1 layer changes with longitude in both hemispheres. Specifically, the F1 layer generally occurs more frequently in the longitudes within ~160°E–90°W at 40–70°N and within 0–150°E at 40–70°S. The peak occurrence probabilities occur around 150°W (>0.6) and 60°E (>0.8) in the Northern and Southern Hemispheres, respectively. The valleys with values near 0 are located at about 120°W at 40–70°S. A minor peak (~0.4) also occurs within ~0–90°E at 40–70°N. These locations depend on latitude and local time. A simulation using the Thermosphere Ionosphere Electrodynamics General Circulation Model ((TIEGCM)) reproduces the observed longitudinal pattern well. Further TIEGCM simulations show that the higher F1 layer occurrence probabilities can be largely explained by longitudinal variations of the O/N2 ratios and also that the dynamic processes, such as the neutral winds above the F1 layer, have additional contributions. These results reveal that the low O/N2 ratios deplete the ionospheric electron density above the F1 layer at middle and high latitudes and thus makes the F1 layer stand out. Key Points: Longitudinal variations of the F1 layer occurrence probabilities at middle and high latitudes are foundThe F1 layer occurrence probabilities peak around 150°W at 40–70°N and 60°E at 40–70°S in summer, solar minimum conditionsHigh F1 layer occurrence probabilities are associated with low O/N2 ratios and the consequent electron density depletion above the hmF1
- Subjects
IONOSPHERE; LATITUDE; SOLAR activity; ELECTRON density; METEOROLOGY
- Publication
Journal of Geophysical Research. Space Physics, 2019, Vol 124, Issue 11, p9592
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2018JA026236