This study uses two forms of the Palmer Drought Severity Index(PDSI),namely the PDSI_TH(potential evapotranspiration estimated-by the Thornthwaite equation)and the PDSI_PM(potential evapotranspiration estimated by the...This study uses two forms of the Palmer Drought Severity Index(PDSI),namely the PDSI_TH(potential evapotranspiration estimated-by the Thornthwaite equation)and the PDSI_PM(potential evapotranspiration estimated by the FAO Penman-Monteith equation),to characterize the meteorological drought trends during 1960–2016 in the Loess Plateau(LP)and its four subregions.By designing a series of numerical experiments,we mainly investigated various climatic factors'contributions to the drought trends at annual,summer,and autumn time scales.Overall,the drying trend in the PDSI_TH is much larger than that in the PDSI_PM.The former is more sensitive to air temperature than precipitation,while the latter is the most sensitive to precipitation among all meteorological factors.Increasing temperature results in a decreasing trend(drying)in the PDSI_TH,which is further aggravated by decreasing precipitation,jointly leading to a relatively severe drying trend.For the PDSI_PM that considers more comprehensive climatic factors,the drying trend is partly counteracted by the declining wind speed and solar radiation.Therefore,the PDSI_PM ultimately shows a much smaller drying trend in the past decades.展开更多
基金National Natural Science Foundation of China,No.41877159The National Key Research and Development Program of China,No.2017YFA0603704The Scholarship from China Scholarship Council(CSC),No.201906270109。
文摘This study uses two forms of the Palmer Drought Severity Index(PDSI),namely the PDSI_TH(potential evapotranspiration estimated-by the Thornthwaite equation)and the PDSI_PM(potential evapotranspiration estimated by the FAO Penman-Monteith equation),to characterize the meteorological drought trends during 1960–2016 in the Loess Plateau(LP)and its four subregions.By designing a series of numerical experiments,we mainly investigated various climatic factors'contributions to the drought trends at annual,summer,and autumn time scales.Overall,the drying trend in the PDSI_TH is much larger than that in the PDSI_PM.The former is more sensitive to air temperature than precipitation,while the latter is the most sensitive to precipitation among all meteorological factors.Increasing temperature results in a decreasing trend(drying)in the PDSI_TH,which is further aggravated by decreasing precipitation,jointly leading to a relatively severe drying trend.For the PDSI_PM that considers more comprehensive climatic factors,the drying trend is partly counteracted by the declining wind speed and solar radiation.Therefore,the PDSI_PM ultimately shows a much smaller drying trend in the past decades.
