Hydrological Environment in Southeast Asia

到目前为止，为1998年国际收支所做的初步研究和筹备工作如下：1)在位于brraa的Om Koi雷达范围内的清迈TMD站安装了一个测量雨滴分布和降雨强度的仪。2)在曼谷进行了每天4次的初步增强型雨水探空观测。在1996年和1997年分别于5月至6月和8月至9月在清迈和乌汶拉差他尼建立了4周的TMD站点。7.3)对于湄南河流域典型土地覆盖类型之一的非灌溉水田，在素可泰西部建立了一个配备10米PBL塔的观测基地和一个探空释放点。素。在该观测基地开展了AWS/GAME-PAM的运行试验、波文比法、涡动相关法和带通协方差法在表面通量估算中的比较、4 ~ 8次/天的增强雷达探空观测等初步研究。(4)在清迈附近的KU Kog Ma森林水文实验流域建设50m PBL塔，并于1997年2月中旬开始初步观测。7.5)在素可泰地区周边开展了不同类型土地覆盖的流动观测，作为固定通量观测的补充。6)启动了湄南河流域中尺度大气模式和分布式水文模式的开发。

Preliminary studies and preparatory works done so far towards IOP in 1998 are as follows ;1) A disdromater which measures rain drop distribution as well as rainfall intensity was installed at Chiang Mai TMD station located in the range of Om Koi rader of BRRAA.2) Preliminary enhanced rawinsonde observations with a frequency of 4 times a day were carried out at Banhkok, Chiang Mai and Ubon Ratchathani TMD stations for 4 weeks from May to June and from August to September respectively in both 1996 and 1997.3) For non-irrigated paddy fields which are one of typical land cover types in the Chao Phraya river basin, an observational base equipped with a 10m PBL tower and a sonde releasing site was established at west Sukhothai. Sukhothai. Some preliminary studies such as operational test of AWS/GAME-PAM,comparison in durface flux estimation among Bowen Ratio, Eddy Correlation and Band-Pass Covariance methods, enhanced rawinsonde observations with a frequency of 4-8 times a day, etc.were carried out at this observational base.4) A 50m PBL tower was constructed at Kog Ma forest hydrologic experimental watershed of KU near Chiang Mai, and preliminary observations were started from the middle of February, 1997.5) Mobile observations for various types of land cover which are planned to complement the fixed flux observations were carried out around Sukhothai area.6) Development of meso-scale atmospheric model and distributed hydrologic model for the Chao Phraya river basin has been initiated.