Influence of seasonal variation of neutral winds on the coupling between North and South Hemispheres in a realistic Earth main field  

作　　者：YANG YaFen CHEN ChuXin 

机构地区：[1]School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China

出　　处：《Science China Earth Sciences》2009年第10期1661-1672,共12页中国科学（地球科学英文版）

基　　金：Supported by National Natural Science Foundation of China (Grant Nos. 40674092, 40890163);the Foundation of Key Project of Chinese Academy of Sciences (Grant No. KJCX2-YW-T13-3)

摘　　要：The neutral wind dynamo contributes significantly to the ionospheric electrodynamics, and the variation of the neutral winds thus affects the ionosphere. Here we study the effects of the seasonal variation of the winds in a realistic Earth main field. The two-dimensional ionospheric dynamo equation is expressed in the framework of a revision of the International Geomagnetic Reference Field (IGRF) under the assumptions of equipotential field lines and conservation of current. A revision of IGRF and typical uniform conductance are used to isolate the effects of the seasonal variation of the winds. Our results show that the potential and the currents in solstice seasons are much different from those in equinox seasons. The gradients of the potential are steeper in solstice seasons than in equinox sea- sons, and similarly the shell currents are stronger in solstice seasons, due to the stronger neutral winds, than in equinox seasons. Correspondingly, the Birkeland currents in solstice seasons are 2-3 times larger than those in equinox seasons, and that the Birkeland currents are much stronger in winter than in summer. Consequently, this suggests that the couplings between North and South Hemi-spheres are much stronger in solstice seasons than in equinox seasons, and likewise they are stronger in winter than in summer.The neutral wind dynamo contributes significantly to the ionospheric electrodynamics, and the variation of the neutral winds thus affects the ionosphere. Here we study the effects of the seasonal variation of the winds in a realistic Earth main field. The two-dimensional ionospheric dynamo equation is expressed in the framework of a revision of the International Geomagnetic Reference Field (IGRF) under the assumptions of equipotential field lines and conservation of current. A revision of IGRF and typical uniform conductance are used to isolate the effects of the seasonal variation of the winds. Our results show that the potential and the currents in solstice seasons are much different from those in equinox seasons. The gradients of the potential are steeper in solstice seasons than in equinox seasons,and similarly the shell currents are stronger in solstice seasons, due to the stronger neutral winds, than in equinox seasons. Correspondingly, the Birkeland currents in solstice seasons are 2–3 times larger than those in equinox seasons, and that the Birkeland currents are much stronger in winter than in summer. Consequently, this suggests that the couplings between North and South Hemispheres are much stronger in solstice seasons than in equinox seasons, and likewise they are stronger in winter than in summer.

关 键 词：neutral winds seasonal variation shell CURRENTS Birkeland CURRENTS COUPLING REALISTIC EARTH MAIN FIELD 

分 类 号：P425.4[天文地球—大气科学及气象学]