NCEP/NCAR reanalysis data and a 30-year precipitation dataset of observed daily rainfall from 109 gauge stations are utilized in this paper.Using the REOF we analyzed the spatial distribution of precipitation in the 1...NCEP/NCAR reanalysis data and a 30-year precipitation dataset of observed daily rainfall from 109 gauge stations are utilized in this paper.Using the REOF we analyzed the spatial distribution of precipitation in the 109 stations in the Yangtze River Basin in Meiyu periods from 1978 to 2007.The result showed that the spatial distribution of precipitation in the Yangtze River Basin can be divided into the south and north part.As a result,relationships between an atmospheric heating source(hereafter called <Q_1>) over the Asian region and the precipitation on the south and north side of Yangtze River in Meiyu periods were separately studied in this paper.The results are shown as follows.The flood/drought to the north of Yangtze River(NYR) was mainly related to the <Q_1> over the East Asia summer monsoon region:when the <Q_1> over the Philippines through Western Pacific and the south China was weakened(strengthened),it would probably result in the flood(drought) in NYR;and the precipitation on the south side of Yangtze River(SYR)was related to the <Q_1> over the east Asia and Indian summer monsoon region:when the <Q_1> over the areas from south China to the northern East China Sea and Yellow Sea and south-eastern Japan was strengthened(weakened),and the <Q_1> over the areas from the Bay of Bengal to south-eastern Tibetan Plateau was weakened(strengthened),it will lead to flood(drought) in SYR.展开更多
Due to their huge socio-economic impacts and complex formation causes,extreme and continuous drought events have become the focus and nodus of research in recent years.In the midsummer(July-August)of 2022,a severe dro...Due to their huge socio-economic impacts and complex formation causes,extreme and continuous drought events have become the focus and nodus of research in recent years.In the midsummer(July-August)of 2022,a severe drought event occurred in the whole Yangtze River Basin(YRB),China.During that period,the precipitation in the upper,middle and lower reaches of the YRB dropped over 40%less than the 1961-2021 climatic mean,which had never happened previously.Furthermore,the temperature was the highest during 1961-2022.The record-breaking magnitude of less rainfall and high temperature directly led to the continuous development of this extreme drought event.An atmospheric moisture budget analysis revealed that the YRB midsummer rainfall anomaly was dominated by the anomalous powerful vertical moisture advection,which was derived from the strongest descending motion over the whole YRB in the 2022 midsummer during 1981-2022.The western Pacific subtropical high(WPSH)during the midsummer remained stronger,more westward and lasted longer than the climatic mean.As a result,the whole YRB was controlled by a positive geopotential height centre.Further evidence revealed that the anomalous subtropical zonal flow played a crucial role in inducing the extreme descent over the YRB.Moreover,the anomalous upper-tropospheric easterly flow over the YRB in 2022 is the strongest during 1981-2022,modulating the generation of the unprecedented descent anomaly over the YRB.The likelihood that an integrated connection of severe drought in East Asia and flood in West Asia and northwestern South Asia would increase when the extremely strong easterly anomalies in the upper troposphere emerged and induced descending adiabatic flow on the eastern sides of the Tibetan Plateau.The results of this study can provide scientific insights into the predictability of extreme drought events and provide ways to improve predictions.展开更多
In late July 2018, a compound drought and heat event(CDHE) occurred in the middle of the Yangtze River basin(MYRB) and caused great damage to the national economy. The CDHE over the MYRB has been documented to be link...In late July 2018, a compound drought and heat event(CDHE) occurred in the middle of the Yangtze River basin(MYRB) and caused great damage to the national economy. The CDHE over the MYRB has been documented to be linked with intraseasonal oscillations(ISOs) from different regions. However, specific roles of different ISOs on the development of the CDHE cannot be separated in the observational analysis. By using partial lateral forcing experiments driven by ISO in the Weather Research and Forecasting(WRF) model, we found that the midlatitude ISO generated by a westerly wave train in the upper troposphere played an important role in this heatwave and drought event in the northern MYRB, causing a regional average temperature rise of 1.65°C and intensification of drought over23.49% of the MYRB area. On the other hand, the ISO associated with the Pacific-Japan(PJ)-like teleconnection wave train in the lower troposphere induced a more pronounced impact on the event, causing an average temperature rise of 2.44°C, intensifying drought over 29.62% of the MYRB area. The MYRB was mainly affected by northward warm advection driven by the westward extension of the western North Pacific subtropical high in the early period of the CDHE development. In the late period, because of the establishment of a deep positive geopotential height field through the troposphere leading to intensive local subsidence, there was a remarkable temperature rise and moisture decrease in the MYRB. The results will facilitate a better understanding of the occurrence of CDHE and provide empirical precursory signals for subseasonal forecast of CDHE.展开更多
基金National Natural Science Foundation of China(41275080)China Meteorological Administration Special Public Welfare Research Fund(GYHY201306022)Open Research Fund Program of Plateau Atmosphere and Environment Key Laboratory of Sichuan Province(PAEKL-2010-C3)
文摘NCEP/NCAR reanalysis data and a 30-year precipitation dataset of observed daily rainfall from 109 gauge stations are utilized in this paper.Using the REOF we analyzed the spatial distribution of precipitation in the 109 stations in the Yangtze River Basin in Meiyu periods from 1978 to 2007.The result showed that the spatial distribution of precipitation in the Yangtze River Basin can be divided into the south and north part.As a result,relationships between an atmospheric heating source(hereafter called <Q_1>) over the Asian region and the precipitation on the south and north side of Yangtze River in Meiyu periods were separately studied in this paper.The results are shown as follows.The flood/drought to the north of Yangtze River(NYR) was mainly related to the <Q_1> over the East Asia summer monsoon region:when the <Q_1> over the Philippines through Western Pacific and the south China was weakened(strengthened),it would probably result in the flood(drought) in NYR;and the precipitation on the south side of Yangtze River(SYR)was related to the <Q_1> over the east Asia and Indian summer monsoon region:when the <Q_1> over the areas from south China to the northern East China Sea and Yellow Sea and south-eastern Japan was strengthened(weakened),and the <Q_1> over the areas from the Bay of Bengal to south-eastern Tibetan Plateau was weakened(strengthened),it will lead to flood(drought) in SYR.
基金sponsored by the Natural Science Foundation of China(42175078)the Joint Open Project of KLME&CIC-FEMD,NUIST(KLME202207)+1 种基金Special Program for Innovation and Development of China Meteorological Administration(CXFZ2022J030)the Review and Summary Special Project of China Meteorological Administration(FPZJ2023-163).
文摘Due to their huge socio-economic impacts and complex formation causes,extreme and continuous drought events have become the focus and nodus of research in recent years.In the midsummer(July-August)of 2022,a severe drought event occurred in the whole Yangtze River Basin(YRB),China.During that period,the precipitation in the upper,middle and lower reaches of the YRB dropped over 40%less than the 1961-2021 climatic mean,which had never happened previously.Furthermore,the temperature was the highest during 1961-2022.The record-breaking magnitude of less rainfall and high temperature directly led to the continuous development of this extreme drought event.An atmospheric moisture budget analysis revealed that the YRB midsummer rainfall anomaly was dominated by the anomalous powerful vertical moisture advection,which was derived from the strongest descending motion over the whole YRB in the 2022 midsummer during 1981-2022.The western Pacific subtropical high(WPSH)during the midsummer remained stronger,more westward and lasted longer than the climatic mean.As a result,the whole YRB was controlled by a positive geopotential height centre.Further evidence revealed that the anomalous subtropical zonal flow played a crucial role in inducing the extreme descent over the YRB.Moreover,the anomalous upper-tropospheric easterly flow over the YRB in 2022 is the strongest during 1981-2022,modulating the generation of the unprecedented descent anomaly over the YRB.The likelihood that an integrated connection of severe drought in East Asia and flood in West Asia and northwestern South Asia would increase when the extremely strong easterly anomalies in the upper troposphere emerged and induced descending adiabatic flow on the eastern sides of the Tibetan Plateau.The results of this study can provide scientific insights into the predictability of extreme drought events and provide ways to improve predictions.
基金Supported by the National Natural Science Foundation of China(41875111 and 41975073)Special Program for Innovation and Development of China Meteorological Administration(CXFZ2022J031).
文摘In late July 2018, a compound drought and heat event(CDHE) occurred in the middle of the Yangtze River basin(MYRB) and caused great damage to the national economy. The CDHE over the MYRB has been documented to be linked with intraseasonal oscillations(ISOs) from different regions. However, specific roles of different ISOs on the development of the CDHE cannot be separated in the observational analysis. By using partial lateral forcing experiments driven by ISO in the Weather Research and Forecasting(WRF) model, we found that the midlatitude ISO generated by a westerly wave train in the upper troposphere played an important role in this heatwave and drought event in the northern MYRB, causing a regional average temperature rise of 1.65°C and intensification of drought over23.49% of the MYRB area. On the other hand, the ISO associated with the Pacific-Japan(PJ)-like teleconnection wave train in the lower troposphere induced a more pronounced impact on the event, causing an average temperature rise of 2.44°C, intensifying drought over 29.62% of the MYRB area. The MYRB was mainly affected by northward warm advection driven by the westward extension of the western North Pacific subtropical high in the early period of the CDHE development. In the late period, because of the establishment of a deep positive geopotential height field through the troposphere leading to intensive local subsidence, there was a remarkable temperature rise and moisture decrease in the MYRB. The results will facilitate a better understanding of the occurrence of CDHE and provide empirical precursory signals for subseasonal forecast of CDHE.
