首页|春季长江中下游旱涝的环流特征及对前期海温异常的响应

春季长江中下游旱涝的环流特征及对前期海温异常的响应

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  • 国家科技期刊平台
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春季长江中下游降水有显著的年际、年代际变化特征,进入21世纪以来长江中下游春季降水偏少现象频繁发生.根据中国国家气候中心160站月平均降水资料和美国国家环境预报中心/国家大气研究中心(NCEP/NCAR)月平均再分析资料,重点探讨春季(3-5月)长江中下游地区降水异常的环流特征、可能成因、机理以及对外强迫的响应.春季长江中下游降水异常偏多(少)的环流主要特征是:高层200 hPa风场上东亚副热带西风急流中心位置比气候态偏北(南)；中层500 hPa亚洲地区的阻塞高压主要发生在乌拉尔山(鄂霍次克海)附近、西太平洋副热带高压位置偏北(南)；低层850hPa风场的东亚沿海地区为偏南(北)风距平,有利于(不利于)水汽向长江中下游地区输送.大气环流内部动力过程的分析指出:东亚地区上空Eliassen-Palm(EP)通量散度在40°N为正(负)异常、30°N为负(正)异常,有利于东亚高空西风急流中心位置偏北(南),从而导致春季长江中下游降水偏多(偏少).春季长江中下游降水异常偏多(少)年最显著的前期外强迫信号表现为赤道太平洋海温呈现厄尔尼诺(拉尼娜)型.
The circulation characteristics of spring precipitation anomalies over the Yangtze River valley and their response to the preceding SSTA
The spring precipitation over the Yangtze River valley is characterized by obvious variability on interdecadal and interannual timescales.The drought events over the Yangtze River valley tend to occur more frequently since 2000.The characteristics of interannual variability of spring (March-May) precipitation over the Yangtze River valley are analyzed by using the observed data at the 160 stations in China and the monthly National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis dataset during 1951-2009.The analyzed results show that the spring precipitation over the Yangtze River valley is above (below) normal while the East Asian jet stream shifts northward (southward),a blocking high pattern persists over the Ural Mountain (Okhotsk Sea),the position of the western Pacific subtropical high is norther (souther) than that of the climatic mean state,and the southerly wind anomaly over southern China and associated water vapor transport at lower levels are intensified (weakened).Further analyses indicate the northward (southward) shift of the East Asian jet is due to the upper levels divergence (convergence) of Eliassen-Palm flux anomalies over the mid-latitudes of East Asia (90°-130°E,40°N) and the converse pattern in the south (30°N).Moreover,the El Ni(n)o (La Ni(n)a)-like sea surface temperature anomalies over the tropical Pacific Ocean is closely related to the anomalies of the atmospheric circulation which cause more (less) spring rainfall over the Yangtze River valley.

Spring precipitation over the Yangtze River valleyEast Asian circulationQuasi-stationary planetary wavesSSTA

李超、张庆云

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中国科学院大气物理研究所国际气候与环境科学中心,北京,100029

中国科学院大学,北京,100049

中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京,100029

春季长江中下游降水 东亚环流 准定常行星波 海温异常

国家自然科学基金面上项目全球变化研究国家重大科学研究计划项目国家重点基础研究发展规划(973计划)国家重点基础研究发展规划(973计划)

409750222012CB9578042013CB4302012009CB421401

2013

10.11676/qxxb2013.033

气象学报
中国气象学会

气象学报

CSTPCDCSCD北大核心
影响因子：1.565
ISSN：0577-6619
年,卷(期)：2013.71(3)
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