jgg     2012 32 (1):  105-109    ISSN: 0412-1961  CN: 21-1139/TG ANALYSIS AND COMPARISON OF TRAJECTORY DISTURBING GRAVITY CALCULATED BY SEVERAL COMPUTATIONAL MODELS Ma Biao 1) ;Liu Xiaogang 1,2) ;and Zhang Liping 2) 1)Institute of Surveying and Mapping, Information and Engineering University, Zhengzhou 450052;2)Xi’an Research Institute of Surveying and Mapping, Xi’an 710054 Received: 1900-01-01  Revised: 1900-01-01  Online: null Supporting info null