jgg     2013 33 (4):  100-103    ISSN: 0412-1961  CN: 21-1139/TG INFLUENCE OF TROPOSPHERIC REFRACTION CORRECTIONS ON  PRECISE POINT POSITIONING CONSIDERING VERTICAL DEFLECTION Xi’an Division of Surveying and Mapping, Xi’an 710054 Received: 2013-03-08  Revised: null  Online: 2013-08-16 Supporting info