jgg     2015 35 (2):  326-330    ISSN: 0412-1961  CN: 21-1139/TG The Application and Analysis of Wide-Area Polynomial  Approximation in Gravity Field Disturbance Fitting 1〓Institute of Geographic Spatial Information, Information Engineering University, 62 Kexue Road, Zhengzhou 450001, China 2〓The PLA 63883 Troops, Luoyang 710000, China Received: 2014-04-18  Revised: null  Online: 2015-04-15 Supporting info