jgg     2014 34 (2):  142-145    ISSN: 0412-1961  CN: 21-1139/TG INFLUENCE OF GRAVITY FIELD MODELS ON ORBIT  DETERMINATION OF LEOS 1）Geomatics College，Shandong University of Science and Technology，Shandong Qingdao 266590 2）Chinese Academy of Surveying and Mapping，Beijing 100830 Received: 2013-08-30  Revised: null  Online: 2014-04-21 Supporting info