Reprocessing of Shirase shipborne gravity data

To compile consistent data sets of Japanese Antarctic Research Expedition (JARE) shipborne gravity data, we applied drift and offset corrections to data sets obtained from JARE-27 to -52 by using a new satellite altimetric gravity model as the reference. Konishi et al. (2006) had previously conducted drift and offset corrections for data obtained up to and including JARE-46 so that the shipborne data fitted the satellite altimetric gravity data of grav.img.11.1 (Sandwell, 2004). Following the method of Konishi et al. (2006), we extracted gravity values from the altimetric gravity model of grav.img.20.1 (Sandwell, 2012) along the ship tracks, and then compared these values with those of the shipborne gravity data. These comparisons revealed large discrepancies near the turning points of the ship tracks, and large drifts and offsets in some of the data sets. We removed data that contained large discrepancies, and applied drift and offset corrections to the remaining data by assuming polynomial functions of time as the drift model. These reprocessed data sets were used for estimating crustal structure near Syowa Station