An improved geomagnetic data selection algorithm for global geomagnetic field modelling

A spherical harmonic degrees 60, global internal field model is described (called BGS/G/L/0706). This model includes a degree 15 core and piecewise-linear secular variation model and is derived from quiet-time Ørsted and Champ satellite data sampled between 2001.0 and 2005.0. For the satellite data selection, a wide range of geomagnetic index and other data selection filters have been used to best isolate suitably quiet magnetospheric and ionospheric conditions. Only a relatively simple, degree one spherical harmonic, external field model is then required. It is found that a new 'Vector Magnetic Disturbance' index ( VMD ), the existing longitude sector A indices, the auroral zone index IE , and the polar cap index PC are better than Kp and Dst at rejecting rapidly varying external field signals at low, middle, auroral and polar latitudes. The model quality is further enhanced by filling spatial and temporal gaps in the quiet data selection with a second selection containing slightly more disturbed data. It is shown that VMD provides a better parametrization than Dst of the large-scale, rapidly changing, external field. The lithospheric field model between degrees 16 and 50 is robust and displays good coherence with other recently published models for this epoch. BGS/G/L/0706 also shows crustal anomalies consistent with other studies, although agreement is poorer in the southern polar cap. Intermodel coherency reduces above about degree 40, most likely due to incompletely filtered signals from polar ionospheric currents and auroral field aligned currents. The absence of the PC index for the southern hemisphere for 2003 onwards is a particular concern.     

中国导游翻译第一人王连义教授

中国导游翻译第一人王连义教授杨新军（北京大学城市与环境学系北京：１００８７１）王连义教授是我国著名的旅游接待管理、导游专家，现任国旅培训中心主任，曾任历届中国导游大赛裁判长。他在国旅总社从事旅游翻译、导游工作多年，对我国导游事业的兴起与发展作出了重大...     

南极布兰斯菲尔德海峡的地球物理场特征与构造发育史

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