摘要:
热带降雨测量卫星(tropical rainfall measuring mission,TRMM)的降雨数据覆盖范围广,时间分辨率高,是区域干旱监测的一种有效数据源.将0.25°空间分辨率的TRMM 3B43数据降尺度处理成0.05°空间分辨率数据,用以构建降水量距平百分率(Pa指数)和Z指数,对黄淮海地区2010年冬季到201 1年春季的干旱时空演化特征进行监测与分析,并计算同期的标准化降水指数(standardized precipitation index,SPI)对监测结果进行验证.研究结果表明,降尺度数据具有较高的可靠性,与实测数据的拟合结果R2 >0.76;Pa指数突出降水盈亏程度,能够有效监测区域尺度干旱,但缺乏空间分布规律;Z指数以Person-Ⅲ型分布拟合降水量,能够很好地监测干旱的时空演化特征,但干旱等级划分相对困难;利用Pa指数对Z指数干旱等级划分进行修正,其结果与SPI相关程度R2>0.75,表明Pa和Z指数用于干旱监测的有效性,为区域尺度干旱监测提供了一种切实可行的方法.
Abstract:
TRMM (tropical rainfall measuring mission) precipitation data,covering a wide range with high temporal resolution,is an effective data source to monitor drought on a regional scale.The spatial resolution of 0.25° TRMM 3B43 data was processed using the downscaling method.The downscaling data with 0.05° spatial resolution were used to construct a percentage of monthly precipitation anomalies (Pa index) and Z index,and the two indices were used to monitor the temporal and spatial change of drought from the winter of 2010 to the spring of 2011 in the Huanghuai Hai plain.The standardized precipitation index (SPI) during the same period was also calculated to verify the results.The results showed that the downscaling results had higher reliability with the fitting result R2 higher than 0.76.Pa index that emphasizes gains and losses of precipitation can be used for drought monitoring on the regional scale,but it lacks the space distribution of drought;Z index fitting the precipitation based on the Person-Ⅲ distribution is ideal for monitoring the temporal and spatial distribution of drought,but the drought grade is difficult to divide.The drought grade of Pa index was used to correct the drought grade of Z index.Two indices and SPI had higher degree of correlation with R2 greater than 0.75,indicating that Pa and Z index is effective for drought monitoring.The results achieved by the authors could provide a practical means for monitoring drought on a regional scale.
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