The potential change of drought measured by the Palmer Drought Severity Index(PDSI)is projected by using a coupled climate system model under a Representative Pathway 8.5(RCP8.5)scenario.The PDSI changes calculated by...The potential change of drought measured by the Palmer Drought Severity Index(PDSI)is projected by using a coupled climate system model under a Representative Pathway 8.5(RCP8.5)scenario.The PDSI changes calculated by two potential evapotranspiration algorithms are compared.The algorithm of Thornthwaite equation overestimates the impact of surface temperature on evaporation and leads to an unrealistic increasing of drought frequency.The PM algorithm based on the Penman-Monteith equation is physically reasonably and necessary for climate change projections.The Flexible Global Ocean-Atmosphere-Land System model,Spectral Version 2(FGOALS-s2)projects an increasing trend of drought during 2051–2100 in tropical and subtropical areas of North and South America,North Africa,South Europe,Southeast Asia,and the Australian continent.Both the moderate drought(PDSI<–2)and extreme drought(PDSI<–4)areas show statistically significant increasing trends under an RCP8.5 scenario.The uncertainty in the model projection is also discussed.展开更多
Intensity and variability of droughts are considered inIranduring the period 1951 to 2005. Four variables are considered: the Palmer Drought Severity Index (PDSI), the soil moisture, the temperature and the precipitat...Intensity and variability of droughts are considered inIranduring the period 1951 to 2005. Four variables are considered: the Palmer Drought Severity Index (PDSI), the soil moisture, the temperature and the precipitation (products used for the analysis are downloaded from the NCAR website). Link with the climatic indexLa Ninais also considered (NOAA downloadable products is used). The analysis is based on basic statistical approaches (correlation, linear regressions and Principal Component Analysis). The analysis shows that PDSI is highly correlated to the soil moisture and poorly correlated to the other variables—although the temperature in the warm season shows high correlation to the PDSI and that a severe drought was experienced during 1999-2002 inthe country.展开更多
Based on the monthly precipitation and air temperature from 1960 to 1989 in the Luanhe River Basin, the standardized precipitation evapotranspiration index （SPEI） and standardized precipitation index （SPI） at thre...Based on the monthly precipitation and air temperature from 1960 to 1989 in the Luanhe River Basin, the standardized precipitation evapotranspiration index （SPEI） and standardized precipitation index （SPI） at three- and six-month time scales and the self-calibrating Palmer drought severity index （sc-PDSI） were calculated to evaluate droughts in the study area. Temporal variations of the drought severity from 1960 to 1989 were analyzed and compared based on the results of different drought indices, and some typical drought events were identified. Spatial distributions of the drought severity according to the indices were also plotted and investigated. The results reveal the following： the performances of different drought indices are closely associated with the drought duration and the dominant factors of droughts; the SPEI is more accurate than the SPI when both evaporation and precipitation play important roles in drought events; the drought severity shown by the sc-PDSI is generally milder than the actual drought severity from 1960 to 1989; and the evolution of the droughts is usually delayed according to the scPDSI. This study provides valuable references for building drought early warning and mitigation systems in the Luanhe River Basin.展开更多
基金Carbon Budget and Related Issues of the Chinese Academy of Sciences(Grant No.XDA0 5110301)Public Science and Technology Research Funds Projects of Ocean(201105019-3)
文摘The potential change of drought measured by the Palmer Drought Severity Index(PDSI)is projected by using a coupled climate system model under a Representative Pathway 8.5(RCP8.5)scenario.The PDSI changes calculated by two potential evapotranspiration algorithms are compared.The algorithm of Thornthwaite equation overestimates the impact of surface temperature on evaporation and leads to an unrealistic increasing of drought frequency.The PM algorithm based on the Penman-Monteith equation is physically reasonably and necessary for climate change projections.The Flexible Global Ocean-Atmosphere-Land System model,Spectral Version 2(FGOALS-s2)projects an increasing trend of drought during 2051–2100 in tropical and subtropical areas of North and South America,North Africa,South Europe,Southeast Asia,and the Australian continent.Both the moderate drought(PDSI<–2)and extreme drought(PDSI<–4)areas show statistically significant increasing trends under an RCP8.5 scenario.The uncertainty in the model projection is also discussed.
文摘Intensity and variability of droughts are considered inIranduring the period 1951 to 2005. Four variables are considered: the Palmer Drought Severity Index (PDSI), the soil moisture, the temperature and the precipitation (products used for the analysis are downloaded from the NCAR website). Link with the climatic indexLa Ninais also considered (NOAA downloadable products is used). The analysis is based on basic statistical approaches (correlation, linear regressions and Principal Component Analysis). The analysis shows that PDSI is highly correlated to the soil moisture and poorly correlated to the other variables—although the temperature in the warm season shows high correlation to the PDSI and that a severe drought was experienced during 1999-2002 inthe country.
基金supported by the National Natural Science Foundation of China(Grant No.41171220)the Program for Changjiang Scholars and Innovative Research Team in University of the Ministry of Education of China(Grant No.IRT13062)+2 种基金the Programme of Introducing Talents of Discipline to Universities(the 111 Project,Grant No.B08048)the Jiangsu Provincial Collaborative Innovation Center for World Water Valley and Water Ecological Civilizationthe National Cooperative Innovation Center for Water Safety and Hydro-Science
文摘Based on the monthly precipitation and air temperature from 1960 to 1989 in the Luanhe River Basin, the standardized precipitation evapotranspiration index （SPEI） and standardized precipitation index （SPI） at three- and six-month time scales and the self-calibrating Palmer drought severity index （sc-PDSI） were calculated to evaluate droughts in the study area. Temporal variations of the drought severity from 1960 to 1989 were analyzed and compared based on the results of different drought indices, and some typical drought events were identified. Spatial distributions of the drought severity according to the indices were also plotted and investigated. The results reveal the following： the performances of different drought indices are closely associated with the drought duration and the dominant factors of droughts; the SPEI is more accurate than the SPI when both evaporation and precipitation play important roles in drought events; the drought severity shown by the sc-PDSI is generally milder than the actual drought severity from 1960 to 1989; and the evolution of the droughts is usually delayed according to the scPDSI. This study provides valuable references for building drought early warning and mitigation systems in the Luanhe River Basin.
