Using global positioning system for orthometric height determination for gravity surveys in Ladakh Himalaya

摘要

Though GPS can be used for precise3-D positioning, the hight thus measured is spheroidal which needs to be converted to the orthometric height for any practical use. This requires knowledge of the geoid undulation that can either be measured using GPS/levelling technique, or can be modelled from gravity data. We carried out extensive field measurements along a 100 km long transect in Ladakh Himalaya to study the viability of using the GPS for orthometric height determinations required for gravity survesy. Geoid of the study area was also predicted using global gravity models, e.g. OSU91 and EGM96. It is seen that even on high and difficult terrain like that of the Himalaya, GPS can be used for orthometric height determination with an absolute accuracy of 1-2 m.