Tongji-Grace02s, a static unconstrained GRACE-only gravity field model

Tongji-Grace02s, a static unconstrained GRACE-only gravity field model up to degree and order 180 was developed by Tongji University under the sponsorship of National Natural Science Foundation of China (41474017). To derive Tongji-Grace02s, the modified short-arc approach which estimates errors of non-conservative acceleration and attitude observations was adopted, and the GRACE-only data (including orbits, range-rates, non-conservative accelerations and attitudes) over the period Jan. 2003 to Jul. 2016 were used. The quality of Tongji-Grace02s is remarkably better than Tongji-GRACE01. In computing Tongji-Grace02s, neither constraint nor regularization was applied.