Precipitation Characteristics over Indonesian Maritime Continent Observed by TRMM Satellite and Boundary Layer Radars
S. Mori (1), J. Hamada (1), M. D. Yamanaka (3)
(1) Frontier Observation Research System for Global Change (FORSGC)
(3) FORSGC/Institute of Science and Technology, Kobe University
It is important to understand the characteristics of convective activity, including distribution of precipitation and its diurnal variation, in tropical region precisely regarding the study on heat and water circulations of Asian monsoon. In a current research on Asian monsoon, they have been examined using in situ rain gauge network, geostationary meteorological satellites, and atmospheric reanalysis data set. As a result, it is gradually clarified that they have a strong relation to topographical features and are made of complicated interaction among various scales of convective systems. Especially, the Indonesian maritime continent is one of regions having the most a lot of precipitation in the world, and a complex of various scales of many islands and surrounding oceans. The changes on precipitation distribution and its diurnal variation in this region have big influence power for the heat and water circulations in not only the Asian monsoon region but also the world climate through the latent heating process. In this study, these features observed by TRMM satellite and two L-band (1.3 GHz) Boundary Layer Radars (BLRs)@at Serpong and Kototabang in Indonesia, which have been operated by Radio Science Center for Space & Atmosphere (RASC) Kyoto University since 1992 and 1998, respectively, are analyzed in this region where an enough observation had not been done up to now. According to TRMM observation of three years, strong precipitation areas are appeared clearly on the southwestern part of Sumatra and the Kalimantan islands, which may be caused by the southwesterly Indian monsoon mainly. Especially, strong precipitation band over a series of small islands in the offshore part along the southwest coastline of Sumatra island, which had not be understood in former studies using ground meteorological observation data and also GPCP data set, is plainly indicated. In the diurnal variation, precipitation peak time appears in the evening on the land area in comparatively big islands e.g. Sumatra and Kalimantan, on the contrary, in the early morning in the offshore area surrounding these islands. Particularly, interested strong correlation between the height in land area and the time delay of precipitation peak is indicated over Sumatra island. These features suggest that both 1) southwesterly Indian monsoon surge of Sumatra island scale, and 2) land-sea breeze and/or mountain-valley breeze of local circulation scale, are strongly related with the characteristics of precipitation. Hourly precipitation data can seldom be obtained in Indonesia, since the precipitation observation is basically based on accumulated daily rainfall data. Moreover, a number of surface wind observation and aerological sonde observation is very limited. Therefore, to investigate this issue, development of dense automatic rain gauge observation network, intensive rawinsonde observation, and local circulation analysis using the BLR wind data are scheduled from this year. Preliminary results of case studies on some precipitation systems observed by both TRMM satellite and the BLRs regarding its lifecycle and local circulation will be presented.
Submittal Information
Name :
Date :
Shuichi Mori
10-Jun-01-13:53:41
Organization :
Theme :
Frontier Observation Research System for Global Change
