蒙古中南部地区的上地幔P波速度结构

利用中蒙国际科技合作专项项目在蒙古中南部地区布设的69个宽频带地震仪在2011年8月-2013年7月所记录的远震波形数据,采用波形相关方法在0.02~0.1 Hz的频段内拾取了18551个有效的P震相相对走时残差数据,进一步采用有限频走时层析成像的方法,反演获取了蒙古中南部下方深达800 km的P波速度结构.结果显示：肯特山下方的低速异常极有可能是推测中的肯特山地幔柱的反映;呼斯坦瑙鲁和曼达尔戈壁西边的低速异常可能与杭爱山高原下的地幔柱或地幔对流有关联;戈壁滩的低速异常带可能和达里甘嘎火山有相同的热来源,可能是该区火成岩存在的深部原因,也可能是戈壁滩及其周边地区地幔柱或下地幔热物质上涌的表现.     

Electric circuits of the disturbed magnetosphere-ionosphere system and their generators

The simplest theory of electric circuits is applied to analysis of the observed large-scale electric field and currents in a disturbed magnetosphere-ionosphere system. Maps of distribution of field-aligned currents (FACs) obtained from ground-based magnetic measurements using the original magnetogram inversion method (MIT) and measurements by satellites were used. A method for circuit determination according to the data of such maps based on the detection of spatial R.N inhomogeneities in each of three Iijima and Potemra FAC zones is proposed. The results of the new method are used to describe some electric field and current generators not known before, new types of current systems in tail lobes and plasma sheet, and the formation and dynamics of new types of three-dimensional systems with auroral electrojets and meridional ionospheric Pedersen current, which have not been paid due attention in the literature.     

Events of August 2, 2002: Features of substorm field-aligned currents

A model of alignment of the field-aligned current generator system in the disturbed magnetosphere is proposed. It has been found that Pedersen currents in the disturbed ionosphere of the auroral oval are meridional. They connect oppositely directed field-aligned currents (FACs) of two adjacent Iijima and Potemra (IP) regions. This supplements the dominant concept of currents in the literature, in which a substorm current wedge plays a major role. During the considered substorm, graphs have been obtained of changes in FAC intensities in each of the three Iijima and Potemra regions of the Northern Hemisphere. These new data suggest that during a disturbance, the Region 1 FAC and the sum of regions 2 and 0 FACs remain equal. The equality means that these three generators form a unified system. Inequalities of intensities between two FACs of different sign simultaneously observed in the dawn and dusk sectors have also been detected in each IP region. A conceptual model is proposed for the formation of this dawn-dusk asymmetry. In the model, in addition to FACs that close up in the ionosphere of the Northern Hemisphere, FACs connecting the two hemispheres are also presented. The conclusion is justified that the global magnetospheric dynamo operates as a voltage generator under relatively quiet (average) conditions, as during storms.