Description of the multi-approach gravity field models from Swarm GPS data

摘要: Abstract. Although the knowledge of gravity Earth has improved considerably with CHAMP, GRACE, and GOCE (see appendices for a list abbreviations) satellite missions, geophysical community has identified need continued monitoring time-variable component with purpose estimating hydrological glaciological yearly cycles long-term trends. Currently, GRACE-FO satellites are the sole dedicated provider these data, while previously GRACE mission fulfilled that role 15 years. There is data gap spanning from July 2017 to May 2018 between end GRACE mission start of GRACE-FO, Swarm have collected gravimetric with their GPS receivers since December 2013. We present high-quality field models (GFMs) from that constitute an alternative independent source which could help alleviate consequences 10-month and GRACE-FO, as well short gaps in existing GRACE-FO monthly time series. The geodetic realized combination different gravity solutions superior any individual model set up the Combination Service Time-variable Gravity Fields (COST-G) under the umbrella International Field (IGFS), part the International Association Geodesy (IAG). exploit this fact deliver highest-quality monthly GFMs, resulting four different estimation approaches. All are unconstrained estimated independently month month. tested added value including kinematic baselines (KBs) our estimation GFMs conclude there no significant improvement. The non-gravitational accelerations measured by accelerometer on board Swarm C were also included our processing determine if would improve quality but we observed only case when the amplitude higher than during the current quiet period solar activity. Using comparison, demonstrate signal in largely restricted spherical harmonic degrees below 12. A 750 km smoothing radius suitable retrieve temporal variations in Earth's over land areas mid-2015 roughly 4 cm equivalent water height (EWH) agreement respect GRACE. Over ocean areas, illustrate more intense 3000 km is necessary resolve large-scale variations, which agree GRACE roughly at level 1 cm EWH, spatial scales observes variations amplitudes between 0.3 EWH. nine selected large basins analysis 0.91 cm, 0.76 cm yr −1 , 0.79 terms of temporal mean, trend, correlation coefficient, respectively. are distributed quarterly basis ESA's Earth Swarm Data Access (at https://swarm-diss.eo.esa.int/ last access: 5 June 2020, follow Level2longterm then EGF) Centre Global Models ( http://icgem.gfz-potsdam.de/series/02_COST-G/Swarm 5 June 2020), as well identified DOI https://doi.org/10.5880/ICGEM.2019.006 (Encarnacao et al., 2019).