基于TRMM卫星资料的渤海降水遥感估算研究

降水是全球能量平衡和水分循环中的关键要素,但海洋区域实时、准确的降水观测资料难以获取,因此,遥感卫星资料在海洋降水及全球能量和水分循环研究领域具有十分重要的应用前景。本文基于1998~2012年6个气象站点(岛屿或海岸带)的实测降水资料,评估TRMM(Tropical Rainfall Measuring Mission)V7版本3B42、3B43两个降水产品对渤海降水量的估算精度,在此基础上,分析并揭示渤海区域年、季和月降水量的时空特征。结果表明:在日尺度,3B42产品对渤海降水量的估算效果总体较差,而在月、年尺度,3B42、3B43产品与实测降水量比较接近,而且,3B43产品的估算精度稍高;总体上,TRMM表现出低估降水的特点,且当实测月降水量大于300 mm时,这种特征尤为显著;1998~2012年,渤海年降水量表现出明显的年际丰枯变化特征,多年均值为631.6 mm;夏季降水量占年降水总量的62.0%,7月是降水量最丰富的月份;空间上,渤海中南部降水量相对较高,而近岸区域降水量相对较低;受大气环流等因素的影响,夏季降水量重心向西北方向偏移,冬季则向东南方向偏移。

Precipitation estimation in the Bohai Sea based on TRMM remote sensing data

Precipitation is a key process in the global energy and water cycle. It is more difficult to accurately measure real-time rainfall of ocean than that of land. The remote sensing data are essential for studying ocean precipitation in global energy and water cycle. In this study, based on the observed rainfall data at 6 climatological stations of island or coastal region during 1998-2012, the performance of 3B42 and 3B43 products of TRMM (Tropical Rainfall Measuring Mission) Version 7 has been assessed over the Bohai Sea. The spatio-temporal characteristics of precipitation in the Bohai Sea have been investigated based on the TRMM data at annual, seasonal and monthly scales. The results showed that at a daily scale, daily precipitation from the 3B42 product of TRMM and at gauge stations was weakly correlated, while at annual and monthly scales, both 3B42 and 3B43 products of TRMM well captured the spatial pattern and temporal variations of precipitation and the 3B43 product had comparatively better performance. In general, the TRMM products slightly underestimated rainfall over the Bohai Sea, especially obvious when the monthly observed rainfall was greater than 300 mm. For the period from1998 to 2012, precipitation over the Bohai Sea showed an inter-annual wet and dry fluctuation with annual mean rainfall of about 631.6 mm. The summer rainfall accounted for 62.0% of the annual rainfall and the maximum average monthly precipitation occurred in July. Spatially, rainfall in the Bohai Sea was higher in the central-south part and lower in the inshore regions. Influenced by atmospheric circulation, the gravity centers of rainfall over the Bohai Sea leaned toward the north-west in summer and toward the east-south in winter.