PRELIMINARY STUDY OF GPS FOR METEOROLOGY TOWARDS DENSE SITE OF TROPOSPHERIC MONITORING ON BANDUNG URBAN AREA

Global Positioning System (GPS), satellite navigation, provides 24 satellites at about 22,000 km above the earth surface. This high orbit causes users should concern to the propagation media i.e Atmosfir, especially the troposphere and ionosphere, in their measurement. Indeed, the propagation delay influence the accuracy of position of the GPS result. Recently, the inversion method of the use of GPS becomes the useful one. This inversion method is also introduced to determine the delay factor in troposphere. By obtaining the delay factor which consists of dry and wet delay, we may extract a wet condition in the troposphere when the GPS observation is carried out. Actually, there is measurement method called radiosonde measurement which measures the troposphere profile. However, the dense distribution of radiosonde site is too cost. This becomes the reason why GPS is introduced to densify the troposphere monitoring sites. We applied this method to the Bandung urban area. The location of GPS observations are LAPAN, BMG Lembang, VSI Tangkubanprahu.The last two sites were used as initial points to determine the wet delay above the LAPAN. BMG also provided the rainfall rate data in the GPS observation time period, in December 1998. This study shows the correlation between the wet delay and the rain occurrence