(1) Khon Kaen University, Thailand
(2) Shizuoka University, Japan
(3) Nagoya University, Japan
GPS observation was set up in the campus of Khon Kaen University, Northeastern Thailand (under the GAME-T Project) to investigate the Precipitable Water Vapor (PWV) change and to understand the characteristics of its seasonal and diurnal changes. The GPS observation has been performed since August 2001. The data obtained from August 2001 to December 2002 were processed and presented in this study.
A Trimble 4000 SSi receiver and a Trible microcentered L1/L2 antenna are used for the observation. The antenna is fixed on the roof of a building and the data is recorded by every 30 minutes for 24 hours a day. The data obtained were processed by using GAMIT software referring the 7 IGS stations data to obtain the Zenith Tropospheric Delay (ZTD) at every one hour. The three hourly PWV was calculated from the ZTD using air pressure and temperature data which were measured by the Thai Meteorological Department.
The results obtained showed that PWV change with a large amptitude from 20 mm. to 60 mm. before the monsoon onset (dry season), it was noted that the PWV increased before rain and decreased after rain. In the wet season, the PWV was almost constant at about 60 mm. or 70 mm. The PWV was related with the humidity. Daily relative humidity measurements were obtained from Rawinsonde data, observed at standard pressure levels : 1000 mbs 850 mbs 700 mbs 600 mbs 500 mbs 400 mbs 300 mbs, or from ground level to 40000 ft. above ground level.
Submittal Information
Name :
Date :
Sununtha Kingpaiboon
29-Aug-04-14:09:44
Organization :
Theme :
Department of Agricultural Engineering, Faculty of Engineering, Khon Kaen University, Thailand