Abstract
Abstract The Newtonian attraction of the atmosphere is a major source of noise in precise gravimetric measurements. A major part of the effect is eliminated using local air pressure records and constant admittance factors. However, vertical mass shifts under constant surface pressure or distant pressure anomalies are not covered by this technique although they affect the gravimeter. In order to improve the atmospheric correction and to evaluate the horizontal components of attraction as well, the Newtonian attraction is computed based on the spatial density distribution derived from three-dimensional weather models. Operational models from the German Weather Service (DWD) of various scales were used, supplemented by a global data set from the European Centre of Medium Weather Forecast (ECMWF) for comparison. The low temporal resolution and the improper point-mass assumption in the near field are tackled by a cylindrical local model by computing the attraction analytically based on local air pressure records with high temporal resolution. It is shown that a height of at least 50 km and global coverage is required to meet a threshold of 1 nm/s2. Neglecting the upper atmosphere leads to an overestimation of the seasonal gravity signal. At distances greater than 10 ° the time consuming three-dimensional computation can be replaced by a two-dimensional surface pressure approach without significant error. The results show differences up to 20 nm/s2 as compared to the linear regression method. The three-dimensional atmospheric correction significantly reduces noise in the time series, giving more insight into other signals such as hydrological effects or deformation processes.
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