XGM2019e is a combined global gravity field model represented by spheroidal harmonics up to degree and order (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 range up to d/o 300 combined with a ground gravity grid which also covers the shorter wavelengths. The ground data consist over land and ocean of gravity anomalies provided by courtesy of NGA (15′ resolution, identical to XGM2016) augmented with topographically derived gravity information over land (EARTH2014). Over the oceans, gravity anomalies derived from satellite altimetry are used (DTU13 with a resolution of 1′). The combination of the satellite data with the ground gravity 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 ground gravity 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 a slightly improved behaviour in the magnitude of a few mm RMS over land as compared to preceding models such as XGM2016, EIGEN6c4 or EGM2008 when validated with independent geoid information derived from GNSS/levelling. Over land and in the spectral range above d/o 719, the accuracy of XGM2019e marginally suffers from the sole use of topographic forward modelling, and geoid differences at GNSS/levelling stations are increased in the order of several mm RMS in well-surveyed areas, such as the US and Europe, compared to models containing real gravity data over their entire spectrum, e.g. EIGEN6c4 or EGM2008. However, GNSS/levelling validation also indicates that the performance of XGM2019e can be considered as globally more consistent and independent of existing high-resolution global models. Over the oceans, the model exhibits an enhanced performance (equal or better than preceding models), which is confirmed by comparison of the MDT’s computed from CNES/CLS 2015 mean sea surface and the high-resolution geoid models. The MDT based on XGM2019e shows fewer artefacts, particularly in the coastal regions, and fits globally better to DTU17MDT which is considered as an independent reference MDT.

中文翻译：

---

组合全球重力场模型 XGM2019e

XGM2019e 是一个组合的全球重力场模型，由高达度和阶 (d/o) 5399 的球面谐波表示，对应于 2' (~ 4 km) 的空间分辨率。作为数据源，它包括在高达 d/o 300 的较长波长范围内的卫星模型 GOCO06s 以及也覆盖较短波长的地面重力网格。地面数据包括由 NGA（15' 分辨率，与 XGM2016 相同）提供的陆地和海洋重力异常，并增加了陆地上的地形衍生重力信息（EARTH2014）。在海洋上空，使用来自卫星高度计的重力异常（DTU13，分辨率为 1'）。卫星数据与地面重力观测的结合是通过使用高达 d/o 719 (15') 的完整正规方程来完成的。除了 d/o 719，计算高分辨率地面重力数据（来自地形和高度计）的块对角最小二乘解。所有计算都在球谐域中进行。在高达 d/o 719 的光谱带中，与之前的模型（如 XGM2016、EIGEN6c4 或 EGM2008）相比，新模型在陆地上几毫米 RMS 的幅度上表现出略微改善的行为，当使用源自 GNSS 的独立大地水准面信息进行验证时/练级。在陆地上和在 d/o 719 以上的光谱范围内，XGM2019e 的精度因仅使用地形前向建模而受到轻微影响，并且 GNSS/水准测量站的大地水准面差异在经过充分测量的区域以几毫米 RMS 的数量级增加，例如美国和欧洲，与包含整个频谱的真实重力数据的模型相比，例如 EIGEN6c4 或 EGM2008。然而，GNSS/水准验证也表明，XGM2019e 的性能可以被认为是全局更一致的，并且独立于现有的高分辨率全局模型。在海洋上，该模型表现出增强的性能（等于或优于之前的模型），这通过从 CNES/CLS 2015 平均海面和高分辨率大地水准面模型计算的 MDT 的比较得到证实。基于 XGM2019e 的 MDT 显示出较少的伪影，尤其是在沿海地区，并且在全球范围内更适合被视为独立参考 MDT 的 DTU17MDT。该模型表现出增强的性能（等于或优于之前的模型），这通过比较从 CNES/CLS 2015 平均海面和高分辨率大地水准面模型计算的 MDT 得到了证实。基于 XGM2019e 的 MDT 显示出较少的伪影，尤其是在沿海地区，并且在全球范围内更适合被视为独立参考 MDT 的 DTU17MDT。该模型表现出增强的性能（等于或优于之前的模型），这通过比较从 CNES/CLS 2015 平均海面和高分辨率大地水准面模型计算的 MDT 得到了证实。基于 XGM2019e 的 MDT 显示出较少的伪影，尤其是在沿海地区，并且在全球范围内更适合被视为独立参考 MDT 的 DTU17MDT。