磁云膨胀速度对无力场磁通量管模型拟合结果的影响  

Role of Expansion Velocity of Magnetic Clouds in Flux Rope Model

作　　者：夏倩[1] 申成龙[1] 汪毓明[1] 叶品中[1] 

机构地区：[1]中国科学技术大学地球和空间科学学院中国科学院基础等离子体物理重点实验室

出　　处：《空间科学学报》2007年第4期271-278,共8页Chinese Journal of Space Science

基　　金：国家自然科学基金项目(40404014;40525014);科技部973项目(2006CB806304);教育部新世纪优秀人才支持计划(NCET04-0578);中国科学院科研启动专项基金;中国科学院空间天气学国家重点实验室开放研究基金共同资助

摘　　要：为了考察磁云膨胀速度对磁通量管模型拟合结果的影响,选取了1998—2003年中15次引起了较大地磁暴(Dst_(min)＜-50nT)的典型磁云事件进行了拟合.与未考虑膨胀速度模型的拟合结果比较,膨胀速度的引入能较好地改善拟合结果,与观测数据的偏差最大能减小30%,并且拟合所得的膨胀速度基本符合统计规律.这个结果说明膨胀的磁通量管模型能更好地反映实际观测的磁云.同时,初步分析了考虑膨胀速度前后磁云各拟合参数的变化.In order to examine the influence of magnetic cloud＇s expansion on its cylindrical flux rope model. The parameter of MC of 15 typical magnetic clouds with Dstmin 〈 -50 nT during 1998-2003 are fitted by applying static and expanding flux rope models, the Multi-MC events and the shock propagation in MC events are not take into account. It is found that the RMS deviations of the fitting results by the expanding model are all less than or equal to those by the static model, it reduced the error up to 30%. That the peak of the magnetic filed in MC is at the leading end in expanding models, this more consistence with the observations than static model. The inferred expansion speeds of these magnetic clouds are consistent with previous statistical results that the expanding speed of MC is at the order of backgoud Alfvén speed. Thus the expanding model matches much more to observed magnetic clouds than the static model. Some differences of the fitted magneticclouds＇ parameters between the two models are analyzed.

关 键 词：磁云 膨胀速度 磁通量管模型 地磁暴 

分 类 号：P172[天文地球—天文学]