The Total Electron Content (TEC) during three great storms, from April to August 2000, was collected by means of a GPS receiver located in Jingzhou (30.4° N, 112.2° E). The time-latitude-dependent features of ionospheric storms are identified using TEC difference images based on the deviations of TEC during storm relative to quiet time. The responses of ionospheric TEC to magnetic storms were analyzed. The results show that: 1) In middle and low latitude, ionospheric storms effects are more apparent in local day time than at night: 2) Ionospheric storm effects are more dominant near the hump of the equatorial anomaly region than in other regions of TEC measurements; 3) The positive effects during the main phase of ionospheric storm may be caused by electric fields in low latitude; 4) During the recovery period of ionospheric storm, the negative phase of storm may be due to the perturbation of the neutral gas composition.
Pei Xiao hong, Yu Sheng bing, Xu Ji sheng, Ma Shu\|ying College of Electronic Information, Wuhan University, Wuhan 430072,China
This paper studies the ionospheric effects associated with the solar eclipse of October 24th, 1995 by means of Computerized Ionospheric Tomography (CIT). Since the reconstructed profiles from experimental CIT are sporadically located in time, a time domain interpolation method based on Singular Value Decomposition (SVD) technique is proposed and applied to extract the ionospheric effects. The effects can be extracted by comparison analysis between the interpolated CIT profiles of the eclipse days and that of the reference day that are time-aligned. A series of figs have been obtained showing the attenuation of photonization effect at low altitudes and the weakening of plasma’s transportation process at high altitudes, etc. The photonization effect recovered to normal level soon after the last contact. The maximum electron density diminishing is observed about 2 h after the eclipse maximum and the effects seem vanished in the hours followed. Analysis on vertical TEC’s latitudinal-temporal variation gives similar conclusions.
Wu Xiong-bin, Xu Ji-sheng, Ma Shu-ying, Tian MaoSchool of Electronic Information, Wuhan University, Wuhan 430072, Hubei, China
