jgg     2013 33 (5):  83-85    ISSN: 0412-1961  CN: 21-1139/TG AN IMPROVED REGIONAL TROPOSPHERIC MODEL AND ITS  APPLICATION IN TRACK 1）Xiamen University of Technology, Xiamen 361000 2）Lanzhou University of Technology, Lanzhou 730050 3）Xinjiang Transportation Planning Surveying and Design Institute, Xinjiang 830006 Received: 2012-12-25  Revised: null  Online: 2013-10-13 Supporting info