多源降水数据在乌江流域干旱监测中的适用性评估

Applicability evaluation on drought monitoring in Wujiang River Basin using multi-source precipitation data

为了弥补地面站点分布稀缺、资料缺测等因素给干旱监测带来的不确定性,选取CMFD、MSWEP、ERA5 3种高时空分辨率降水产品,以乌江流域及其周边15个地面气象站点1979~2016年降水资料为基准,利用标准化降水指数分析评估这3种降水产品在乌江流域的精度及不同时间尺度干旱监测中的适用性。结果表明:CMFD与MSWEP具有较高的探测精度,能准确捕捉乌江流域多年平均降水空间分布,ERA5则存在明显高估现象。在季节尺度和月尺度上,CMFD与MSWEP相关系数均大于0.9,数据精度高于ERA5;CMFD与MSWEP计算的不同时间尺度下的SPI与站点之间存在较高的一致性,在不同时间尺度上的相关系数均高于0.94,而ERA5则随着时间尺度增加与站点之间一致性逐渐降低,相关系数平均值仅有0.46;3种降水产品在干旱频率空间分布的刻画上并没有一种产品表现出绝对优势,但总体来说CMFD要优于MSWEP和ERA5;CMFD在捕捉干旱历时、烈度、峰值和严重度等干旱特征方面表现较优,其次是MSWEP和ERA5。综上所述,CMFD与MSWEP可为流域干旱监测提供数据支撑,ERA5降水数据质量较差,需进一步对其降水数据进行校正。研究成果可为乌江流域的干旱监测、预警等提供数据支撑。

To compensate for the uncertainty in drought monitoring due to scarcity of ground stations and data measurement,we selected three high spatial-temporal resolution precipitation products,CMFD,MSWEP and ERA5,for analysis.By using precipitation data from 15 ground meteorological stations in and around the Wujiang River Basin spanning 1979 to 2016,the accuracies of three precipitation products in the Wujiang River Basin and their suitability for drought monitoring in various time scales were analyzed and evaluated using the standardized precipitation index(SPI).The results revealed that CMFD and MSWEP demonstrate remarkable detection precision,accurately portraying the spatial distribution of annual average precipitation over the Wujiang River Basin,whereas ERA5 exhibits significant overestimation.On both seasonal and monthly scales,the correlation coefficients of CMFD and MSWEP exceed 0.9,indicating a superior data accuracy compared to ERA5.Furthermore,CMFD and MSWEP exhibit high consistency with ground stations in calculating SPI across different time scales,with correlation coefficients surpassing 0.94.Conversely,the consistency between ERA5 and stations diminishes as the time scales augment,resulting in an average correlation coefficient of merely 0.46.Although none of the three precipitation products emerged as a clear winner in portraying the spatial distribution of drought frequency,CMFD generally outperforms MSWEP and ERA5.CMFD also excels in capturing drought duration,intensity,peak and severity,followed by MSWEP and ERA5.In conclusion,CMFD and MSWEP provide valuable data support for drought monitoring in the basin,while the precipitation data quality of ERA5 necessitates further improvement.The outcomes of this research will contribute significantly to drought monitoring and early warning in the Wujiang River Basin.