The experimental gravity field model XGM2019e

XGM2019e is a combined global gravity field model represented through spheroidal harmonics up to d/o 5399, corresponding to a spatial resolution of 2’ (~4 km). As data sources it includes the satellite model GOCO06s in the longer wavelength area combined with terrestrial measurements for the shorter wavelengths. The terrestrial data itself consists over land and ocean of gravity anomalies provided by courtesy of NGA (identical to XGM2016, having a resolution of 15’) augmented with topographically derived gravity over land (EARTH2014). Over the oceans, gravity anomalies derived from satellite altimetry are used (DTU13, in consistency with the NGA dataset). The combination of the satellite data with the terrestrial observations is performed by using full normal equations up to d/o 719 (15’). Beyond d/o 719, a block-diagonal least-squares solution is calculated for the high-resolution terrestrial data (from topography and altimetry). All calculations are performed in the spheroidal harmonic domain. In the spectral band up to d/o 719 the new model shows over land a slightly improved behavior over preceding models such as XGM2016, EIGEN6c4 or EGM2008 when comparing it to independent GPS leveling data. Over land and in the spectral range above d/o 719 the accuracy of XGM2019e suffers from the sole use of topographic forward modelling; Hence, errors are increased in well-surveyed areas compared to models containing real gravity data, e.g. EIGEN6c4 or EGM2008. However, the performance of XGM2019e can be considered as globally more homogeneous and independent from existing high resolution global models. Over the oceans the model exhibits an improved performance throughout the complete spectrum (equal or better than preceding models).XGM2019e是一款组合式全球重力场模型，采用椭球谐函数（spheroidal harmonics）展开至阶数与次数（d/o）5399，对应的空间分辨率为2角分（约4千米）。其数据来源为长波波段的卫星模型GOCO06s与短波波段的地面测量数据的融合。地面数据覆盖陆地与海洋区域：由美国国家地理空间情报局（NGA）提供的重力异常数据（与分辨率为15角分的XGM2016一致），陆地区域额外补充了基于地形衍生的重力数据（EARTH2014）；海洋区域则采用卫星测高衍生的重力异常数据（DTU13，与NGA数据集保持一致）。卫星数据与地面观测数据的融合在阶数与次数719（对应15角分）以内采用完整法方程完成计算；当阶数与次数超过719时，则针对源自地形与测高数据的高分辨率地面数据，采用分块对角最小二乘求解方案。所有计算均在椭球谐函数域内进行。在阶数与次数719以内的频谱波段中，相较于XGM2016、EIGEN6c4、EGM2008等前代模型，新模型在陆地区域的表现略有提升，该结论可通过独立GPS水准（GPS leveling）数据验证。在陆地区域且阶数与次数高于719的频谱范围中，XGM2019e仅依赖地形正演建模，因此精度有所下降；相较于包含实测重力数据的模型（如EIGEN6c4或EGM2008），在测量覆盖较充分的区域，其误差会有所增大。不过，XGM2019e的整体性能在全球范围内更为均匀，且不依赖于现有高分辨率全球重力场模型。在海洋区域，该模型在全频谱范围内均表现出更优的性能，优于或等同于前代模型。

搜集汇总

背景与挑战

背景概述

XGM2019e是一个实验性全球重力场模型，最高阶数5399，空间分辨率约4公里，结合卫星和地面数据源。模型在陆地上低阶部分略有改进，但高阶精度受地形建模限制；在海洋上表现更优且全球均匀性更好，适用于地球科学和重力场研究。