위성관측(MSU)에서 유도된 열대 태평양에서의 강수 알고리즘 = Rainfall Algorithm derived from Satellite MSU Observations over thd Tropical Pacific Ocean

다국어 초록 (Multilingual Abstract)

Rainfall algorithm over the tropical Pacific Ocean has been derived, based on monthly mean data of the satellite-observed Microwave Sounding Unit(MSU) channel l(Ch1) at 50.3 ㎓ and channel 2(Ch2) at 53.74 ㎓ brightness temperature, and the rain-gauge observations at 23 island stations during the period from January 1980 to December 1999. In the algorithm, the Ch1 temperature sensitive to low tropospheric hydrometeors is heavily weighted, and the Ch2 temperature which reflects middle tropospheric temperature is also included because of the rainfall dependence on latitude in the tropics. Compared to previous study of Spencer(1993), the present algorithm has a better simulation with respect to rain-gauge values, showing the improvement of 55 ㎜/month in bias, 33 ㎜/month in RMS error, and 0.13 in correlation on an annual basis. This tendency is more pronounced in the convective region of 17.5S-20N.
Previous rainfall records from various data sources which include the output of Tropical Rainfall Measuring Mission(TRMM) have been intercompared in order to estimate uncertainties among them Rainfall data, obtained from satellite infrared observation, are more deviated from the average of the records over the subtropics possibly due to clouds without bringing rain. In the meantime, the rainfall derived from microwave
observation shows more discrepancy with the average in the high latitude ocean because of the surface emission of sea ice. The seasonal movement and rainfall amounts in the InterTropical Convergence Zone(ITCZ) and the South Pacific Convergence Zone(SPCZ) have been also discussed with interannual variation. Satellite-observed rainfall formula in this study provides rainfall data for data-sparse ocean, and helps us to understand freshwater budget and air-sea interaction.