Progress in technology for the 2005 height determination of Qomolangma Feng (Mt. Everest)

In 2005 China carried out a new geodetic campaign for the height determination of Qomolangma. Feng-Mt. Everest (OF in short). The technical progresses in geodesy for the 2005 campaign are presented in the paper. GPS positioning was the key technique in the campaign. After summarizing the experiences and lessons of the GPS positioning on the OF summit in the previous OF height determination campaigns, some measures were taken to raise the accuracy and reliability of the height determination with GPS techniques. In order to raise the accuracy of the height determination of the OF summit with classical geodetic techniques, laser ranging was used together with the trigonometric levelling in the 2005 campaign. It is the first time in China the thickness of the ice-snow layer on the OF summit was measured by ground penetrating radar integrated with GPS. The local gravity field and geoid in the OF area was improved on the basis of earth gravity field model integrated with new ground gravity data, DTM data and GPS leveling data in the OF area. In the 2005 campaign the normal height and orthometric height (height above sea level) of the snow surface of the OF summit were obtained as 8846.67 m and 8847.93 m respectively. The orthometric height of the rock surface of the OF summit is 8844.43 m, and the thickness of the ice-snow layer on the OF summit is 3.50 m.