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《Chinese Journal of Geophysics》 2016-01
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Study on F-lacuna characteristics at Zhongshan station,Antarctic

YANG Sheng-Gao;ZHANG Bei-Chen;FANG Han-Xian;LIU Jun-Ming;LIU Jian-Jun;LI Chong-Yin;HU Hong-Qiao;PAN Ye-Sen;ZHOU Xiao-Ke;Institute of Meteorology and Ocean,PLA Univ.of Sci.& Tech.;Polar Research Institute of China;Chinese Academy of Sciences(CAS);Unit NO.96631 of PLA;  
As a typical phenomenon on ionograms observed at high latitudes,F-lacuna usually occurs in summer daytime.It manifests itself as partial or total disappearance of normal ionogram traces,which usually prevents the determination of ionospheric parameters from ionograms.Due to the sparse data in polar region,its mechanism is still controversial.The ionograms recorded by Zhongshan Digisonde 4D were used to carry out this study.According to the missing traces concerning either F1 region,F2region,or the whole F region,the F-lacuna can be classified intothree types,i.e.,F1-lacuna,F2-lacuna and total lacuna,respectively.This paper concentrated on F2-lacuna mechanism.Based on the F-lacuna events with manual judgments,we studied all three types of F-lacuna occurrence rate in different solar wind velocity conditions,then focused on the simultaneous observations from GPS TEC,HF radar and DMSP satellite,during a F2-lacuna case.The statistical on the daily F-lacuna occurrence frequency relation to averaged solar wind velocity indicates that F2-lacuan occurs more frequent with solar wind velocity increasing.The observations show that a substorm occurred during the F2-lacuna period.In the mean time,the in-situ TEC decreases,Bragg back scattering of Super DARN HF radar enhances,but the particle precipitation is not obvious.Through the statistical and case study,we analyzed F2-lacuna occurrence mechanism.On one hand,the heating effect from F-B instability triggered by substorm enhances the O+recombination rate of upper F region,leading to the decreased electron density of F2 region and subsequently the decreased TEC.On the other hand,the F-B instability disturbance produces small-scale irregularities along the field aligned observed by SuperDARN HF radar.
【Fund】: 国家重点基础研究发展计划(2012CB825603);; 国家自然科学基金(41104090 41274148 40505005 41431072 41274149);; 国家重点实验室专项基金(Y22612A33S);; 南北极环境综合考察与评估专项(CHINARE-2014-02-03);; 浦东新区科技发展基金项目(PKC2013-207)资助
【CateGory Index】: P352.7
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