南极大陆及周边海域地形和均衡重力效应的计算

Calculation of Terrain and Isostatic Gravity Effects in Antarctica and Its Surroundings

使用BEDMAP2关于南极大陆及周围海域和JGP95E关于全球表面高程、冰厚和冰下及水深地形数据,采用球坐标系下的扇形球壳块重力效应公式,在极方位投影直角坐标网格节点上计算了南极大陆及周围海域的近区及远区的地形和艾黎均衡重力效应。南极大陆冰盖带来可观的正重力效应,南大洋负重力效应又影响到了南极内陆,全球地形/均衡重力效应与局部地形高低有关联性,而低负值区主要分布在环南极的陆坡。获得的约1n mile间距的地形和艾黎均衡重力效应网格数据可用于南极大陆及周边海域的重力改正,提供准确、一致的布格重力异常和艾黎均衡重力异常。

Usingdata of surface elevation, ice-thickness, subglacial and submarine topography for the Antarctic continent and its surrounding seas from BEDMAP2 and also for the whole world from JGP95E, we calculate the global gravity terrain effects and the Airy isostatic effects at each grid node of rectangular coordinates of the polar azimuthal projection for the Antarctic continent and its surrounding seas.Gravity effects both from the near zones and the far zones are computed by means of the same formula of gravity effects for fan-shaped block of spherical crust based on spherical coordinates.The Antarctic ice sheet has a considerable contribution to gravity effects, but the Southern Ocean has large positive gravity effects on the inland Antarctica. The global terrain/ isostatic gravity effects are locally correlated with topography undulation, and their lowest negative belt corresponds to the Antarctic continental slope.Our computed about 1 nautical mile interval grid data of the global terrain and isostatic gravity effects can be used to correct gravity anomalies for accurately, consistently computing Bouguer gravity anomalies and Airy isostatic gravity anomalies in the Antarctic continent and its surrouding seas.