This study investigates the influences of boreal summer intraseasonal oscillation(BSISO), which originates from the equatorial Indian Ocean and prevails over the Indo-Pacific region, on precipitation over Southeast Ch...This study investigates the influences of boreal summer intraseasonal oscillation(BSISO), which originates from the equatorial Indian Ocean and prevails over the Indo-Pacific region, on precipitation over Southeast China, including South China and Yangtze River Valley. The results indicate that the BSISO-related precipitation anomalies are remarkably different between early summer(May–June) and late summer(July–August). The BSISO-related precipitation anomalies tend to appear more northward in late summer in comparison with early summer. Accordingly, the BSISO is significantly related to precipitation anomalies over South China during many phases in early summer but related to very weak anomalies during all the phases in late summer. Such northward shifts of precipitation anomalies from early summer to late summer are clearest during phases 4 and 7, when the lower-tropospheric anticyclonic and cyclonic circulation anomalies dominate over the subtropical western North Pacific, respectively. Finally, we explain the differences between early and late summers through the seasonal northward migration of climatological equivalent potential temperature gradient, which is located in the South China during early summer but migrates northward to the YRV during late summer.展开更多
Using daily precipitation data from 110 stations in Southeast China from 1960 to 2012,the extreme precipitation(EP)events associated with monsoon and tropical cyclones were examined using the Objective Synoptic Analys...Using daily precipitation data from 110 stations in Southeast China from 1960 to 2012,the extreme precipitation(EP)events associated with monsoon and tropical cyclones were examined using the Objective Synoptic Analysis Technique.In Southeast China,the extreme precipitation associated with tropical cyclones(TEP),which mainly occur in the summer(July–September),accounted for 27.9%of the total extreme precipitation amount,with 40–50%in the coastal regions.While the regional mean TEP amount showed an inconspicuous trend,total EP and monsoon EP(MEP)both showed an increasing trend,with the MEP trend being statistically significant.Although there was little change in the frequency of tropical cyclones affecting Southeast China,the TEP contribution to frequency increased with increasing EP threshold and the frequency of TEP with daily precipitation of more than 300 mm showed an increasing trend in the background of global climate change.The upward trend in the highest-threshold TEP events presents a challenge for mitigation of the damage associated with tropical cyclones.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 41721004)。
文摘This study investigates the influences of boreal summer intraseasonal oscillation(BSISO), which originates from the equatorial Indian Ocean and prevails over the Indo-Pacific region, on precipitation over Southeast China, including South China and Yangtze River Valley. The results indicate that the BSISO-related precipitation anomalies are remarkably different between early summer(May–June) and late summer(July–August). The BSISO-related precipitation anomalies tend to appear more northward in late summer in comparison with early summer. Accordingly, the BSISO is significantly related to precipitation anomalies over South China during many phases in early summer but related to very weak anomalies during all the phases in late summer. Such northward shifts of precipitation anomalies from early summer to late summer are clearest during phases 4 and 7, when the lower-tropospheric anticyclonic and cyclonic circulation anomalies dominate over the subtropical western North Pacific, respectively. Finally, we explain the differences between early and late summers through the seasonal northward migration of climatological equivalent potential temperature gradient, which is located in the South China during early summer but migrates northward to the YRV during late summer.
基金supported by the National Natural Science Foundation of China (Grant No.41375056 and 91224004)the Meteorological Specialty Foundation of China (Grant No.GYHY201206013)
文摘Using daily precipitation data from 110 stations in Southeast China from 1960 to 2012,the extreme precipitation(EP)events associated with monsoon and tropical cyclones were examined using the Objective Synoptic Analysis Technique.In Southeast China,the extreme precipitation associated with tropical cyclones(TEP),which mainly occur in the summer(July–September),accounted for 27.9%of the total extreme precipitation amount,with 40–50%in the coastal regions.While the regional mean TEP amount showed an inconspicuous trend,total EP and monsoon EP(MEP)both showed an increasing trend,with the MEP trend being statistically significant.Although there was little change in the frequency of tropical cyclones affecting Southeast China,the TEP contribution to frequency increased with increasing EP threshold and the frequency of TEP with daily precipitation of more than 300 mm showed an increasing trend in the background of global climate change.The upward trend in the highest-threshold TEP events presents a challenge for mitigation of the damage associated with tropical cyclones.
