NAME =  Akira Watanabe  
ORGANIZATION =  Fukushima University  
ADDRESS =  1,Kanayagawa Fukushima ,960-1296  
COUNTRY =  Japan  
PHONE =  024-548-8203  
FAX =  024-548-8203  
E-MAIL =  may@educ.fukushima-u.ac.jp  
POSTER_ONLY =  no  
THEME =  T3  
DATE =  09-Aug-04-16:42:13  
ABSID = T3AW09Aug04164213 
TITLE = A change of mean physical quantity in the monsoon and pre-monsoon. 
AUTHOR_1 = A. Watanabe 
INSTITUTION_1 = Fukushima University 
AUTHOR_2 = Y. Tachibana 
INSTITUTION_2 = Tokai University 
AUTHOR_3 = S. Ogino 
INSTITUTION_3 = Kobe University  
AUTHOR_4 = Y. Shibagaki 
INSTITUTION_4 = Osaka Electro-Communication University 
AUTHOR_5 = T. Ohsawa 
INSTITUTION_5 = Kobe University  
AUTHOR_6 = Y., M. Yamanaka 
INSTITUTION_6 = Kobe University  
AUTHOR_7 = T. Oki 
INSTITUTION_7 = University of Tokyo 
AUTHOR_8 = T. Satomura 
INSTITUTION_8 = Kyoto University 
AUTHOR_9 = A. Sumi 
INSTITUTION_9 = CCSR University of Tokyo 
AUTHOR_10 = K. Mushiake 
INSTITUTION_10 = Fukushima University 
ABSTRACT =  We carried out rawinsonde observation to understand the atmospheric circulation in the pre-monsoon and the monsoon periods over Thailand. We observed the upper atmospheric structure by rawinsonde four times a day from Apr. 15 to Jul.15, and from Aug.15 to Sep15, 1998 at Chiang Mai, Ubon Ratchathani and Bangkok in Thailand. It is very important to understand a difference of the atmospheric circulation between the pre-monsoon and the monsoon periods. We are able to divide into 3 classification on Apr. 15 to May 13, May 14 to Jun. 15, and Sep. 15 from Aug. 15, to understand the fluctuation of the monsoon. And we calculated the mean field of the meteorological element every 3 classification. The pressure decreases about 2hPa under the 5km in the rainy season than the pre-monsoon. But, the pressure increases about 3hPa over the 5km in the rainy season than the pre-monsoon. Furthermore, the temperature decreases about 2¡î under the3km, and the temperature increases about 4¡î over the 3km in the rainy season than the pre-monsoon. Accordingly, we are unable to explain the pressure decrease of the lower layer with the temperature change. We are conceivable that this mean field was made with a convective activity.  It became clear that decreasing of pressure of the lower layer strengthens the south wind, and convective instability is strengthened by advection of water vapor by the south wind.