Enhanced Short-Wavelength Marine Gravity Anomaly Using Depth Data
Ruijie Hao, Xiaoyun Wan, Richard Fiifi Annan
Abstract
Satellite altimetry cannot accurately derive the short-wavelength component of ocean gravity anomaly. Since the short-wavelength seabed topography affects the gravity anomaly, we can forward the short-wavelength gravity anomaly by using seabed topography to make up for the shortcomings of altimetry. Based on the Global Marine Gravity Anomaly Version 1 (GMGA1) previously released by our group, and on Parker’s formula, the short-wavelength gravity anomaly is forwarded by using the seabed topographic model SRTM15+V2.4, and a new product, Global Marine Gravity Anomaly Version 2 (GMGA2), is obtained. Compared with internationally recognized gravity field products such as Scripps Institution of Oceanography (SIO) V32.1 and DTU17, the accuracy of GMGA2 is 2.5 mGal, which is 0.7 mGal higher than GMGA1, and the absolute differences smaller than 5 mGal account for more than 96%. An evaluation using ship-borne gravity data showed the accuracy of GMGA2 is 4.8 mGal, which is 0.3 mGal higher than GMGA1. It is concluded from the above results that using the forward method with water depth data significantly improves the short-wavelength gravity anomaly of the altimetry-derived gravity field model, and the accuracy of GMGA2 is close to that of the advanced international level.