Abstracts for the 5th International GAME Conf.

3-5 October 2001

Aichi Trade Center

Nagoya Japan

Seasonal change of precipitable water vapor obtained from GPS data in Thailand

Mikio Satomura (1), Mikiko Fujita (2), Tosiyuki Nakaegawa (3), Teruyuki Kato (4)

GPS observations have been performed to monitor the atmospheric change of Asian Monsoon at 6 stations in Thailand since April 1998 as one of the GAME-T projects. Trimble 4000SSE or 4000SSi receivers are used and the antennas are fixed at the roofs of the buildings. The data are logged at 30 seconds interval for 24 hours per day. The logged data are automatically downloaded to the hard disk of a personal computer at the observation site. The data at Bangkok, Chiang Mai, Nong Khai and Ubon Rachatani were analyzed from April 1998 to December 1999 because we got the meteorological data in the period concerned. The GAMIT ver 9.95 software was used and the tropospheric zenith delay was obtained at every 1 hour referring to seven IGS stations at shao (Shanghai, China)，yar1 (Yaragadee，Australia)，tskb (Tsukuba, Japan), guam (Guam Island，USA), lhas (Lhasa，Tibet), coco (Cocos Island，Australia), and ntus (Nanyang Technological Univ., Singapole). In order to calculate the dry term of the delay, we need the data of air pressure at the observation site, but only the pressure at mean sea level was available. We estimated the altitudes at the stations from mean sea level from ellipsoidal height from GPS data and geoidal height from EGM96 geoid model. The wet term was obtained by subtracting the dry term from zenith tropospheric delay, and the PWV can be calculated from the wet term There is much lack of data, but we can get the following results, 1. There are always high PWV values in the wet season and PWV seldom changes except small diurnal or semi-diurnal change. 2. PWV changes with a large amplitude in 1 or 2 weeks cycle in the dry season. 3. PWV in the dry season is almost equal to that of the wet season when it is high, but its average value is lower than that of the wet season.

Submittal Information

Name : Date :
    Mikio Satomura
    11-Jun-01-05:09:53
Organization : Theme :
    Faculty of Science, Shizuoka University
    Theme 4
Address : Presentation :
    836 Oya, Shizuoka 422-8529
    Poster or oral
Country : Abstract ID :
    Japan
    T4MS11Jun01050953
Phone : Fax :
    054-238-4945
    054-238-0491
E-mail :
    semsato@ipc.shizuoka.ac.jp