Observational study of daytime ionospheric irregularities associated with typhoon  

作　　者：XIAO SalGuan SHI JianKui ZHANG DongHe HAO YongQiang HUANG WeiQuan 

机构地区：[1]State Key Laboratory of Space Weather,Center for Space Science and Applied Research,Chinese Academy of Sciences,Beijing 100190,China [2]Department of Geophysics,Peking University,Beijing 100871,China

出　　处：《Science China(Technological Sciences)》2012年第5期1302-1304,共3页中国科学（技术科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 40974091, 41174135 and 40921063);the Specialized Research Fund for State Key Laboratories

摘　　要：Spread-F is a manifestation of ionospheric irregularities and generally takes place at nighttime. However, it can also be ob- served seldom at daytime, It is recognized that acoustic gravity waves （AGWs） play an important role in triggering plasma instability which results in spread-F in the ionosphere. The typhoon is a main source of the AGWs. In this paper, two cases of ionospheric daytime spread-F in the period of typhoon were analyzed. One case was on July 29, 1988 and the other was on August 01, 1989. The results showed the following： 1） There were some wave-like disturbances appearing in the HF Doppler records firstly, consequently the Doppler echo traces became scattered, which indicated that the ionospheric spread-F was triggered; 2） the blurred echo traces in the both two cases appeared in the morning （08：30-11：30 Beijing time） and lasted for more than two hours; 3） with the blurred echoes gradually weakening, the traveling ionospheric disturbances （TIDs） still ex- isted and became clearer; 4） the frequency shifts in the two of the radio wave in the ionosphere moved downwards. spread-F during the typhoon period in Asian region. cases were both positive, implying the effective reflecting surface These results provide good observational evidence for daytime

关 键 词：ionospheric irregularity SPREAD-F DAYTIME TYPHOON 

分 类 号：P352.4[天文地球—空间物理学] TU972.4[天文地球—地球物理学]