Observations and modeling of UHF-band scintillation occurrence probability over the low-latitude region of China during the maximum activity of solar cycle 24

摘要

The climatological characteristics of UHF-band scintillations over the low-latitude region of China were investigated by analyzing the observationsrecorded at three stations of our regional network of satellite-beacon-basedscintillation monitoring in 2013. The three stations are Hainan (geographic20.0° N, 110.3° E; geomagnetic 10.1° N,177.4° W, dip 28.2°), Guangzhou (geographic23.0° N, 113.0° E; geomagnetic 13.1° N,174.8° W, dip 33.9°) and Kunming (geographic25.6° N, 103.7° E; geomagnetic 15.7° N,176.4° E, dip 39.0°), located at low latitudes of China.The variations of UHF-band scintillation occurrence with latitude, time andseason are presented in detail to understand the morphology and climatologyof ionospheric scintillations over the low-latitude region of China. Anequinoctial asymmetry in the occurrences of scintillation and an obviousdifference of the onset time of scintillations between Hainan and Kunming isnoted in this data set. Subsequently, the ionosonde data are utilized to studythe possible causes of the asymmetry between two equinoxes. The observationssuggest that the mean critical frequency (F2) at 20:00 LT(12:00 UT) in the autumnal equinoctial months (September and October) and thevernal equinoctial months (March and April) has a similar asymmetry. Theratio of the mean F2 between two equinoxes is proportional to theratio between the maximum scintillation occurrence in the autumnal equinox andin the vernal equinox. Therefore, this ratio can act as a proxy for the equinoctialasymmetry in the occurrences of scintillation over the low-latitude region of China, and can be used to model the equinoctial asymmetry in our empiricalclimatological model of scintillation occurrence probability (CMSOP). TheCMSOP can provide the predictions of the occurrences of scintillation overthe low-latitude region of China and was validated in this study.