湖北省夏季不同阶段强降水及其大气低频特征
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摘要
利用1961-2014年湖北省68站逐日降水资料和美国国家海洋和大气管理局环流资料,对比分析了湖北省夏季梅雨期和盛夏期低频强降水事件的基本特征、大气环流形势和低频信号传播特征。结果表明:(1)湖北省夏季降水存在显著的准双周低频周期。(2)相较于盛夏期,梅雨期低频强降水事件次数多,强度强。(3)梅雨期和盛夏期低频强降水事件发生期间的环流形势有着显著的差异。梅雨期,对流层中层东亚沿岸为南北向的波列分布,低层受强索马里越赤道气流和副热带高压外围西南气流共同影响,水汽条件好,东亚存在鞍型场,流场变形,利于形成中尺度气旋系统;盛夏期,对流层中层为欧亚波列分布,低层索马里越赤道气流弱,主要受副热带高压外围水汽输送的影响,日本海以西地区有一异常气旋,其西侧的偏北气流与暖湿气流在30°N附近交汇维持。(4)在强降水事件发生前后,对流层低层的低频正涡度传播特征有较大差异,在梅雨期表现为驻波特征,盛夏期传播更为明显,表现为向西、向南向北传播。
By using the daily precipitation data of 68 stations in Hubei and NCEP/NCAR circulation reanalysis data,the characteristics of the heavy rain events and low-frequency atmospheric features between the Meiyu and midsummer periods are studied.The results indicate that the quasi-biweekly oscillation of precipitation exists obviously in summer over Hubei.Compared with the rains in the midsummer period,lowfrequency heavy rain events in the Meiyu period are seen more often with stronger intensities.There are significant differences of low-frequency heavy rain events between the Meiyu and midsummer period.During Meiyu period,circulations show the distribution of north-south wave trains above the East Asia Littoral in the mid-level troposphere.The combined impact of strong Somali cross-equatorial flow and southwest air current around subtropical high contribute to the abudant water vapor.The saddle-type field of circulations in East Asia and transformed flow field are beneficial to the formation of mesoscale cyclonic systems.In the midsummer period,however,circulations distribute in the pattern of Eurasian wave trains in middle troposphere.In lower troposphere,water vapor comes from subtropical peripheral with the weak Somali cross-equatorial flow.The north air streams from the west of the cyclone to the west of Japan Sea and the south warm-wet air streams from the periphery of subtropical high get intersected and maintained over 30°N.Before and after the heavy rain events,there are obvious differences of the low-frequency positive vorticity propagation in low troposphere.The low-frequency positive vorticity during the Meiyu period shows the characteristics of standing wave while in the midsummer,it propagates westward,southward and northward obviously.
By using the daily precipitation data of 68 stations in Hubei and NCEP/NCAR circulation reanalysis data,the characteristics of the heavy rain events and low-frequency atmospheric features between the Meiyu and midsummer periods are studied.The results indicate that the quasi-biweekly oscillation of precipitation exists obviously in summer over Hubei.Compared with the rains in the midsummer period,lowfrequency heavy rain events in the Meiyu period are seen more often with stronger intensities.There are significant differences of low-frequency heavy rain events between the Meiyu and midsummer period.During Meiyu period,circulations show the distribution of north-south wave trains above the East Asia Littoral in the mid-level troposphere.The combined impact of strong Somali cross-equatorial flow and southwest air current around subtropical high contribute to the abudant water vapor.The saddle-type field of circulations in East Asia and transformed flow field are beneficial to the formation of mesoscale cyclonic systems.In the midsummer period,however,circulations distribute in the pattern of Eurasian wave trains in middle troposphere.In lower troposphere,water vapor comes from subtropical peripheral with the weak Somali cross-equatorial flow.The north air streams from the west of the cyclone to the west of Japan Sea and the south warm-wet air streams from the periphery of subtropical high get intersected and maintained over 30°N.Before and after the heavy rain events,there are obvious differences of the low-frequency positive vorticity propagation in low troposphere.The low-frequency positive vorticity during the Meiyu period shows the characteristics of standing wave while in the midsummer,it propagates westward,southward and northward obviously.
引文
曹鑫,任雪娟,孙旭光,2013.江淮流域夏季持续性强降水的低频特征分析[J].气象科学,33(4):362-370.
曹鑫,任雪娟,杨修群,等,2012.中国东南部5—8月持续性强降水和环流异常的准双周振荡[J].气象学报,70(4):766-778.
岑思弦,巩远发,王霄,2009.2007年夏季淮河流域洪涝与亚洲地区大气低频振荡的关系[J].大气科学,33(6):1286-1296.
陈青,廖玉芳,杨书运,等,2014.低频天气图方法在湖南省雨季强降水过程预报中的影响[J].气象,40(2):223-228.
崔讲学,柯怡明,王仁乔,等,2011.湖北省天气预报手册:暴雨预报[M].北京:气象出版社,22-24.
黄丽娜,高建芸,陈彩珠,等,2014.福建前汛期持续性强降水的大气低频特征分析[J].气象,40(6):723-732.
李崇银,1991.大气低频振荡[M].北京:气象出版社,207.
刘慧斌,温敏,何金海,等,201 2.东北冷涡活动的季节内振荡特征及其影响[J].大气科学,36(5):959-973.
齐艳军,程明虎,仪清菊,2004..98.7湖北特大暴雨的天气分析与降水模拟[J].气象,30(3):12-16.
苏布达,姜彤,任国玉.等,2007.长江流域1960—2004年极端强降水时空变化趋势[J].气候变化研究进展,3(Z1):45-50.
王黎娟,庞玥,于波,等,2014.江淮流域梅雨期持续性强降水及其10—30 d低频环流特征[J].热带气象学报,30(5):85卜860.
王小玲,郭艳君,2009.2008年全球重大天气气候事件概述[J].气象,35(4):108-111.
王遵娅,丁一汇,2008.中国雨季的气候学特征[J].大气科学,32(1):1-13.
魏晓雯,梁萍,何金海,等,2015.大范围持续性强降水过程与30—60d低频降水的联系及其预报指数[J].热带气象学报,31(1):63-70.
夏芸,管兆勇,王黎娟,2008.2003年江淮流域强降水过程与30—70d天低频振荡的联系[J].南京气象学院学报,31(1):33-41.
杨秋明,201 5.2013年初夏长江下游降水低频分量延伸期预报的多变量时滞回归模型[J].气象,41(7):881-889.
尹志聪,王亚非,2011.江淮夏季降水季节内振荡和海气背景场的关系[J].大气科学,35(3):495-505.
袁嫒,任福民,王艳娇,等,2012-2012年华南前汛期降水特征及环流异常分析[J].气象,38(10):1247-1254.
张娇,王东勇,朱佳宁,等,2011.淮河流域持续性强降水的重要前斯信号[J].气象,37(11):1329-1335.
Yang J,Wang B,Wang B,et al,2010.Biweekly and 21-30-day variations of the subtropical summer monsoon rainfall over the Lower Reach of the Yangtze Basin[J].J Climate,23(5),1146-1159.
曹鑫,任雪娟,杨修群,等,2012.中国东南部5—8月持续性强降水和环流异常的准双周振荡[J].气象学报,70(4):766-778.
岑思弦,巩远发,王霄,2009.2007年夏季淮河流域洪涝与亚洲地区大气低频振荡的关系[J].大气科学,33(6):1286-1296.
陈青,廖玉芳,杨书运,等,2014.低频天气图方法在湖南省雨季强降水过程预报中的影响[J].气象,40(2):223-228.
崔讲学,柯怡明,王仁乔,等,2011.湖北省天气预报手册:暴雨预报[M].北京:气象出版社,22-24.
黄丽娜,高建芸,陈彩珠,等,2014.福建前汛期持续性强降水的大气低频特征分析[J].气象,40(6):723-732.
李崇银,1991.大气低频振荡[M].北京:气象出版社,207.
刘慧斌,温敏,何金海,等,201 2.东北冷涡活动的季节内振荡特征及其影响[J].大气科学,36(5):959-973.
齐艳军,程明虎,仪清菊,2004..98.7湖北特大暴雨的天气分析与降水模拟[J].气象,30(3):12-16.
苏布达,姜彤,任国玉.等,2007.长江流域1960—2004年极端强降水时空变化趋势[J].气候变化研究进展,3(Z1):45-50.
王黎娟,庞玥,于波,等,2014.江淮流域梅雨期持续性强降水及其10—30 d低频环流特征[J].热带气象学报,30(5):85卜860.
王小玲,郭艳君,2009.2008年全球重大天气气候事件概述[J].气象,35(4):108-111.
王遵娅,丁一汇,2008.中国雨季的气候学特征[J].大气科学,32(1):1-13.
魏晓雯,梁萍,何金海,等,2015.大范围持续性强降水过程与30—60d低频降水的联系及其预报指数[J].热带气象学报,31(1):63-70.
夏芸,管兆勇,王黎娟,2008.2003年江淮流域强降水过程与30—70d天低频振荡的联系[J].南京气象学院学报,31(1):33-41.
杨秋明,201 5.2013年初夏长江下游降水低频分量延伸期预报的多变量时滞回归模型[J].气象,41(7):881-889.
尹志聪,王亚非,2011.江淮夏季降水季节内振荡和海气背景场的关系[J].大气科学,35(3):495-505.
袁嫒,任福民,王艳娇,等,2012-2012年华南前汛期降水特征及环流异常分析[J].气象,38(10):1247-1254.
张娇,王东勇,朱佳宁,等,2011.淮河流域持续性强降水的重要前斯信号[J].气象,37(11):1329-1335.
Yang J,Wang B,Wang B,et al,2010.Biweekly and 21-30-day variations of the subtropical summer monsoon rainfall over the Lower Reach of the Yangtze Basin[J].J Climate,23(5),1146-1159.
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