The Rock–Water–Ice Topographic Gravity Field Model RWI_TOPO_2015 and Its Comparison to a Conventional Rock-Equivalent Version
The Rock–Water–Ice Topographic Gravity Field Model RWI_TOPO_2015 and Its Comparison to a Conventional Rock-Equivalent Version
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DOI：
10.1007/s10712-016-9376-0
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发表时间：
2016-06
影响因子：
4.6
通讯作者：
T. Grombein;K. Seitz;B. Heck
中科院分区：
文献类型：
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作者：
T. Grombein;K. Seitz;B. Heck
RWI_TOPO_2015是一个新的高分辨率球谐表示地球的地形重力位，是基于一个完善的岩石-水-冰（RWI）的方法。这种方法的特点是将地球地形分为岩石、水和冰块三层。为了允许这些质量与可变密度值的严格的单独建模，重力正演模拟在空间域中使用布置在椭球参考表面上的镶嵌体质量体进行。前一个模型RWI_TOPO_2012基于全球地形数据库DTM 2006.0（数字地形模型2006.0），而新的RWI模型使用了地球2014地形套件的更新高度信息。此外，在RWI_TOPO_2015的情况下，球谐函数中的表示被扩展到次数和阶数2190（以前为1800）。除了所使用的形式主义的介绍之外，还详细描述了RWI_TOPO_2015的处理，并在空间域和频域中分析了所得球谐系数的特性。此外，本文着重于比较的RWI的方法，传统上使用的岩石等效方法。为此，生成一致的岩石等效版本REQ_TOPO_2015，其中水和冰块的高度被压缩为恒定的岩石密度。当在GRS 80椭球体（大地参考系1980）的表面上进行评估时，RWI_TOPO_2015和REQ_TOPO_2015的差异在高度异常、重力扰动和径向-径向重力梯度方面分别达到约1 m、50 mGal和20 mE的最大幅度。虽然这些差异随着椭球体上方高度的增加而减弱，但在当前重力场飞行任务的卫星高度情况下，甚至可以检测到显著的幅度。为了评估其性能，RWI_TOPO_2015、REQ_TOPO_2015和RWI_TOPO_2012针对当前全球地球重力位模型的独立重力信息进行了验证，清楚地表明了新RWI模型的改进。
RWI_TOPO_2015 is a new high-resolution spherical harmonic representation of the Earth’s topographic gravitational potential that is based on a refined Rock–Water–Ice (RWI) approach. This method is characterized by a three-layer decomposition of the Earth’s topography with respect to its rock, water, and ice masses. To allow a rigorous separate modeling of these masses with variable density values, gravity forward modeling is performed in the space domain using tesseroid mass bodies arranged on an ellipsoidal reference surface. While the predecessor model RWI_TOPO_2012 was based on theglobal topographic database DTM2006.0 (Digital Topographic Model 2006.0), the new RWI model uses updated height information of theEarth2014 topography suite. Moreover, in the case of RWI_TOPO_2015, the representation in spherical harmonics is extended to degree and order 2190 (formerly 1800). Beside a presentation of the used formalism, the processing for RWI_TOPO_2015 is described in detail, and the characteristics of the resulting spherical harmonic coefficients are analyzed in the space and frequency domain. Furthermore, this paper focuses on a comparison of the RWI approach to the conventionally used rock-equivalent method. For this purpose, a consistent rock-equivalent version REQ_TOPO_2015 is generated, in which the heights of water and ice masses are condensed to the constant rock density. When evaluated on the surface of the GRS80 ellipsoid (Geodetic Reference System 1980), the differences of RWI_TOPO_2015 and REQ_TOPO_2015 reach maximum amplitudes of about 1 m, 50 mGal, and 20 mE in terms of height anomaly, gravity disturbance, and the radial–radial gravity gradient, respectively. Although these differences are attenuated with increasing height above the ellipsoid, significant magnitudes can even be detected in the case of the satellite altitudes of current gravity field missions. In order to assess their performance, RWI_TOPO_2015, REQ_TOPO_2015, and RWI_TOPO_2012 are validated against independent gravity information of current global geopotential models, clearly demonstrating the attained improvements in the case of the new RWI model.