Abstracts for the 5th International GAME Conf.
3-5 October 2001
Aichi Trade Center
Nagoya Japan
A Difference of Diurnal Variation of Atmospheric Circulation between Wet Season and Dry Season in Tropics
Patipat Patvivatsiri (10), Manabu Yamanaka (11), Taikan Oki (12), Takehiko Satomura (13), Akimasa Sumi (12), Katsumi Mushiake (12), Akira Watanabe (1), Yoshihiro Tachibana (2), Yoshiaki Shibagaki (3), Teruo Oosawa (4), Kinji Furukawa (5), Yukinori Nakajima (6), Teerapont Pogrermdee (10), Warasak Samroeng (10), Dunyapon Bisonyabut (10)
(10) Thai Meteorological Department
(11) Kobe University
(12) University of Tokyo
(13) Kyoto University
(1) Fukushima University
(2) Tokai University
(3) Osaka Electro-Communication University
(4) Gifu University
(5) National Space Development Agency
(6) Remote Sensing Technology
We carried out rawinsonde observation to understand the diurnal variation of atmospheric circulation in wet and dry seasons over Thailand. We observed the upper atmospheric structure by rawinsonde eight times a day from Aug.24 to Aug.30, 1997 (wet season) and Jan.13 to Jan. 21, 2000 (dry season) at NongKhai in Northeastern Thailand. It is very important to understand a difference of the diurnal variation of atmospheric circulation between wet season and dry season. The reason is that the diurnal variation is fundamental oscillation of atmospheric circulation, and makes various periodic atmospheric circulations. In particular, we can understand the role of water vapor in the atmospheric circulation to compare wet season with dry season.
Strong inversion layer appear about 4km above the sea level, and the equivalent potential temperature below the inversion layer generally shows convective instability during the dry season. However, the convective activity is very small. Because the water vapor doesn't condense below the inversion layer, the temperature is high and water vapor is a little. The spectrum density of diurnal variation of temperature, mixing ratio and wind speed in wet season is larger than in dry season. The phase of diurnal variation of temperature, mixing ratio and wind speed in the wet season is later than in the dry season.
The vertical profile of equivalent potential temperature spectrum density and phase discontinue about 8km above the sea level. We think that the difference of diurnal variation is made by the convective activity. Furthermore, the phase of eastward component of wind is large different below 4km above the sea level. The phase difference is about 90 degree (6 hours). And the phase of northward component of wind is large different between 7 km and 10 km above the sea level. The phase difference is about 180degree (12 hours). We think that the phase difference depends on the water vapor distribution which is influenced the inversion layer.
Submittal Information
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1 Kanayagawa Fukushima 960-1296 Japan | |
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may@db2.educ.fukushima-u.ac.jp | |