Using MSU for Quantitatively Rainfall Estimate around TAIWAN Area

• Main Author: 趙俊傑
• Other Authors: 陳萬金
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/52136825943960644694

碩士 === 中正理工學院 === 應用物理學系研究所 === 86 === Due to the lack of rain gauge data on ocean, satellite data are the only measurement to rainfall. Because microwave can penetrate clouds, it possesses more direct measurement to rainfall than visible and infrared data and can be used to estimate rainfall more accurate than the others. Currently, there are three microwave radiometers for rainfall estimate, i.e. Microwave Sounding Unit (MSU), Special Sensor Microwave Imager (SSM/I) and TRMM (Tropical Rainfall Measurement Mission) Microwave Imager (TMI). Because only MSU data are available on the current operational routine, the rainfall estimation is derived by MSU data only. The variation of the brightness temperatures of MSU channel 1 (Tb 1) was found to have a significant relationship with precipitation. Therefore, in this study rainfall was retrieved by MSU Tb1. But before MSU Tb1 was used to derive rainfall, it should be corrected by removing the atmospheric effect. Usually, the atmospheric effect can be calculated by the brightness temperatures of MSU channels 2(Tb 2) and 3(Tb 3). In order to improve the poor resolution of retrieval rainfall, Geostationary Meteorological Satellite 5(GMS-5) data were used at the same time. Therefore mesoscale rainfall estimation can be obtained from MSU and GMS-5 data fusion. The rain gauge measurement was used for comparison. It is shown that there is a same pattern at heavy rainfall situation. Advance Microwave Sounding Unit (AMSU) on board the NOAA-K will be the fourth microwave radiometer for rainfall estimation. Because AMSU has more channels ( 20 channels ) and fine resolutions ( 50km at nadir for AMSU-A, 15km at nadir for AMSU-B ) than MSU, So it is expected to improve the accuracy of rainfall estimate in the near future.