Consistent Estimate of Ultra-High Resolution Earth Surface Gravity Data (UHR-GravDat)

超高分辨率地球表面重力数据将在高分辨率重力场模拟、高程系统统一、地球物理勘探和水文引水等方面发挥重要作用。然而，最先进的全球表面重力数据是不均匀和不完整的，不一致的问题还没有得到适当的解决。由卫星高度计数据反演得到的海洋重力数据即使在1‘间距的情况下也能提供重力异常。然而，用于卫星高度计数据反演的方法对高频误差相当敏感。地球重力数据是由不同来源、不同分辨率和精度的非常不完整的拼凑而成的。5‘重力异常是为生成EGM2008而汇编的，由于版权的关系，这些异常是非公开的。本项目的总体目标是创建、验证和编辑一套全球一致的、空间分辨率为2.5’(约5公里)的超高分辨率地表重力数据。这将通过以下方式实现：(1)在获得海洋和陆地重力数据所需的所有处理步骤中采用一致的标准；(2)对历史、实际和新的高度计飞行任务的轨道进行统一的再处理，以实现对海洋重力数据的密集和最精确的绘图；(3)交叉校准海面高度，将它们改正为动态海洋地形的最新估计，并通过应用区域重力场模型将海洋大地水准面与仅有卫星的重力场结合在一起；(4)实现陆地和航空重力数据的最全面汇编，通过区域重力场模型调查和解决仅有卫星的重力场和陆地重力场之间的不一致，(5)通过新的高分辨率数字高程模型合成重力，并以差分的形式加以利用，以填补特别是陆地重力数据方面的空白；(6)通过船载观测验证海洋重力，并通过与全球导航卫星系统数据和水准高度的比较，验证陆地重力。

Ultra-high resolution Earth surface gravity data will serve important applications as, for example, high resolution gravity field modeling, unification of height systems, geophysical prospecting and hydrological water routing. The state-of-the-art global surface gravity data is, however, inhomogeneous and incomplete with inconsistencies not yet properly addressed. Marine gravity data derived by inverting satellite altimeter data provide gravity anomalies even with 1' spacing. However, the approaches used to invert satellite altimeter data are rather sensitive to high frequency errors. Terrestrial gravity data are a very incomplete patchwork of different sources with different resolution and accuracy. The 5' gravity anomalies, compiled for the generation of EGM2008, are non-public due to copy rights.The general objective of the present project is to create, validate and edit a global set of consistent ultra-high resolution surface gravity data with a spatial resolution of 2.5' (about 5 km). This shall be accomplished by (i) applying consistent standards in all processing steps required to derive marine and land based gravity data, (ii) homogeneously reprocessing the orbits of historical, actual and new altimeter missions to achieve a dense and most precise mapping for the marine gravity data, (iii) cross-calibrating sea surface heights, correcting them for the most recent estimates of the dynamic ocean topography and combining the marine geoid with satellite-only gravity fields by applying regional gravity field modeling, (iv) realizing an utmost comprehensive compilation of terrestrial and airborne gravity data, investigating and resolving inconsistencies between satellite-only gravity fields and terrestrial gravity by regional gravity field modeling, (v) synthesizing gravity by new high-resolution digital elevation models and using this in a differential form to fill gaps, in particular, in terrestrial gravity data, and (vi) validating marine gravity by ship-borne observations and terrestrial gravity by comparison with GNSS data and leveling heights.