The study of the critical frequency of ionosheric sporadic E layer observed at Hainan station in 2002
Abstract
The critical frequency (foEs) parameters of ionospheric Sporadic E (Es) layers observed by DPS-4 digisonde at low latitude Hainan station in the solar high active year 2002 are utilized to analyze the features of the day-to-day distributions and diurnal mean value variations of foEs, average diurnal and daily occurrence rate of Es. The results show: (1) most of foEs values are less than 10 MHz, and the distribution of foEs greater than 10MHz is concentrated in summer; (2) The mean values of foEs rise up rapidly at about 07:00 LT, then reached the maximum at about 13:00 LT and then decrease till 20:00 LT; (3) the average diurnal occurrence rate of Es exits two peaks at about 07:00 and 18:00 LT. (4) The daily occurrence rate of Es is higher in summer, then in autumn or winter, lower in spring. The vertical wind shear theory can interpret well the distribution of foEs values greater than 10MHz and average diurnal occurrence rate of Es. However, it is not enough to explain the diurnal mean value variations of foEs and daily occurrence rate of Es. We suggest the factors such as solar radiation, tides, and planetary scale waves should be considered further to affect the Es. These results are very significant to the study of the ionospheric Es irregularities, especially in the low latitude.
- Publication:
-
39th COSPAR Scientific Assembly
- Pub Date:
- July 2012
- Bibcode:
- 2012cosp...39.2125W