The combined global gravity field model XGM2019e

Abstract

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.

Assessment of HY-2A GM data by deriving the gravity field and bathymetry over the Gulf of Guinea

“…Also, it is expected that future SSH data from the SWOT (Surface Water and Ocean Topography) mission to be launched in September 2021, will contribute significantly to this topic. In addition, the reference model can be replaced by a more recent model such as XGM2019e (Zingerle et al 2020), which may also improve the accuracy of the derived gravity anomalies in the study area.…”

“…2, where the former 360 degrees and orders of EGM2008 are selected as the reference model. Indeed, some other recent gravity field models, such as XGM2019e (Zingerle et al 2020), can also be used as the reference model for deriving gravity anomalies and may help improve the accuracy of the derived gravity anomalies, because more data are used for deriving these models than EGM2008 (Zingerle et al 2020). However, this contribution would…”

India‐Elan Bank‐East Antarctica Breakup, Crustal Architecture, and Margin Evolution: Results From Constrained Potential Field and Process‐Oriented Gravity Modeling of Conjugate Margin Segments

“…In the onshore ECMI, the DSS data are mainly available for the Cuddapah and K-G basins (Kaila & Bhatia, 1981;Kaila et al, 1990) (Sandwell et al, 2014) in offshore and EGM2008 (Pavlis et al, 2012) in the onshore. (b) & (e) degree-10 residual geoid anomaly map obtained after removing long-wavelength geoid contributions up to spherical harmonic degree and order 2-10 from the XGM2019e full spectrum geoid (Pail et al, 2018;Zingerle et al, 2020) ECMI (segment II), and Mahanadi basin (Behera et al, 2004) in the northern part of ECMI (segment III). The refraction velocity-depth plots for these two regions of ECMI are presented in Figure 4a.…”

Gravity Effect of Alpine Slab Segments Based on Geophysical and Petrological Modelling

“…The Bouguer Anomaly (Fig. 1a) is based on the global model XGM 2019 (Zingerle et al, 2019) developed for spherical harmonics up to degree 719, with a resolution of ~25 km (half wavelength). The simple Bouguer Anomaly is calculated from the free-air gravity disturbance with a topographic density of 2670 kg/m 3 , and water density of 1030 kg/m 3 for the offshore https://doi.org/10.5194/se-2020-145 Preprint.…”