A Circulation Index of the Spring Persistent Rainfall in the South of the Yangtze and Its Synoptic Characteristics
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摘要: 利用东亚和西太平洋对流层低层850 hPa纬向风的经向差异,定义了一个可以表征江南春雨变化特征的环流指数,通过诊断分析探讨该指数与降水和大气环流的关系。结果表明:该指数可以较好地反映江南春雨的年际和逐日变化特征。在年际时间尺度上,高指数年江南春雨偏多,而低指数年江南春雨偏少。该指数的逐日变化与江南地区同期逐日降水变化呈显著正相关。在高指数日,我国江南地区的低压系统和西北太平洋地区的副热带高压偏强,江南地区对流层高层辐散增强,低层辐合和高层辐散的增强为春雨发生提供动力抬升条件,有利于春季江南地区降水的产生;低指数日,西北太平洋副热带高压位置偏南,江南至华南地区对流层低层存在弱辐散,这种形势配合下不利于江南春雨的产生。
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关键词:
- 江南春雨;
- 环流指数;
- 西北太平洋副热带高压
Abstract: Using daily precipitation dataset of 2466 stations over China, daily and monthly reanalysis dataset from 1961 to 2016 by National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), a circulation index of spring persistent rainfall (ISPR) is defined based on latitudinal differences of zonal winds in lower troposphere over the region from East Asia to the western Pacific. Relationships of ISPR with spring persistent rainfall and general circulation is investigated. Results show that the westerly wind from the South of the Yangtze to South China and the easterly wind located in the region from Huanghuai to Jianghuai area in spring is beneficial to the spring persistent rainfall in the South of the Yangtze. Using this characteristic, the spring rainfall circulation index in the South of the Yangtze is defined. In high-index cases, rainfall increases in the South of the Yangtze; and in low-index cases, rainfall decreases. Meanwhile, the index defined not only reflect the annual variation of the spring persistent rainfall, but also can reflect the daily variation of the spring persistent rainfall. The index has good synoptic significance, and is positively correlated with the daily precipitation in the South of the Yangtze. A verification using data from 1961 to 2016 in the South of the Yangtze indicates that this definition of index can reflect the precipitation in most years in the South of the Yangtze in spring. Taking the year of 2016 as an example, results show that the index defined has a clear physical meaning. In high-index cases, the plateau trough and the southern branch of westerly trough are more active. The western Pacific high moves northward anomalously. Confluence of the southwesterly wind from the low trough, the western Pacific high and the cold air from the higher latitude occur from the South of the Yangtze to South China. Low level convergence and high level divergence provide dynamic uplifting conditions for spring persistent rainfall in the South of the Yangtze. In low-index cases, the western Pacific high moves southward anomalously, and anticyclone anomalies cover the mainland of China. The existence of weak divergence in the lower troposphere in the South of the Yangtze to South China goes against persistent rainfall. -
图 9 2016年高指数日和低指数日合成的风场(矢量)和散度场(等值线,单位:10-6 s-1)距平(a)高指数日850 hPa,(b)低指数日850 hPa,(c)高指数日500 hPa,(d)低指数日500 hPa,(e)高指数日200 hPa,(f)低指数日200 hPa
Fig. 9 Composite analysis of the wind(the vector) and divergence(the contour, unit:10-6 s-1) anomalies (a)at 850 hPa in high-index cases, (b)at 850 hPa in low-index cases, (c)at 500 hPa in high-index cases, (d)at 500 hPa in low-index cases, (e)at 200 hPa in high-index cases, (f)at 200 hPa in low-index cases
图 10 沿110°~120°E的2016年高指数日(a)和低指数日(b)合成的假相当位温(实线,单位:K)、温度(虚线,单位:K)、垂直环流(矢量)及散度(填色)
Fig. 10 Composite analysis of the pseudo-equivalent potential temperature(the solid line, unit:K), temperature(the dashed line, unit:K), vertical circulation(the vector) and divergence(the shaded) in high-index cases(a) and low-index cases(b) along 110°-120°E
表 1 1961—2016年逐年3月1日—5月15日逐日ISPR与同期逐日江南地区区域平均降水量的相关系数
Table 1 Correlation of daily ISPR to precipitation in the South of the Yangtze from 1 Mar to 15 May during 1961-2016
年份 相关系数 1961 0.56 1962 0.62 1963 0.46 1964 0.34 1965 0.64 1966 0.59 1967 0.48 1968 0.61 1969 0.57 1970 0.62 1971 0.49 1972 0.63 1973 0.48 1974 0.51 1975 0.42 1976 0.33 1977 0.53 1978 0.51 1979 0.42 1980 0.61 1981 0.31 1982 0.22 1983 0.26 1984 0.58 1985 0.32 1986 0.33 1987 0.23 1988 0.36 1989 0.38 1990 0.30 1991 0.15 1992 0.44 1993 0.29 1994 0.26 1995 0.14 1996 0.49 1997 0.35 1998 0.39 1999 0.33 2000 0.59 2001 0.41 2002 0.22 2003 0.32 2004 0.35 2005 0.36 2006 0.39 2007 0.16 2008 0.60 2009 0.15 2010 0.37 2011 0.58 2012 0.58 2013 0.59 2014 0.46 2015 0.34 2016 0.46 -
[1] 李麦村, 潘菊芳, 田生春, 等.春季连续低温阴雨天气的预报方法.北京:科学出版社, 1977:3-4. http://www.oalib.com/paper/4179795 [2] 吴宝俊, 彭治班.江南岭北春季连阴雨研究进展.科技通报, 1996, 12(2):65-70. http://www.cnki.com.cn/Article/CJFDTOTAL-KJTB602.000.htm [3] 刘宣飞, 袁旭.江南春雨的两个阶段及其降水性质.热带气象学报, 2013, 29(1):99-105. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=rdqxxb201301012 [4] Tian S F, Yasunari T.Climatological aspects and mechanism of spring persistent rains over central China.J Meteor Soc Japan, 1998, 76(1):57-71. doi: 10.2151/jmsj1965.76.1_57 [5] 陈绍东, 王谦谦, 钱永甫.江南汛期降水基本气候特征及其与海温异常关系初探.热带气象学报, 2003, 19(3):260-268. http://www.cqvip.com/QK/92292A/2003003/8166247.html [6] 万日金, 吴国雄.江南春雨的时空分布.气象学报, 2008, 66(3):310-319. doi: 10.11676/qxxb2008.029 [7] 万日金, 吴国雄.江南春雨的气候成因机制研究.中国科学(D辑), 2006, 36(10):936-950. http://www.docin.com/p-678157827.html [8] 晏红明, 王灵, 李蕊.1-3月欧亚大陆热力变化及其与中国降水的关系.应用气象学报, 2016, 27(2):209-219. doi: 10.11898/1001-7313.20160209 [9] 袁佳双, 郑庆林.西北太平洋冷还问对东亚初夏大气环流影响的数值研究.应用气象学报, 2006, 17(3):310-315. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20060355&flag=1 [10] 王澄海, 王式功, 杨德保, 等.中国西北春季降水与太平洋海温讷的相关特征.应用气象学报, 2001, 12(3):383-384. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20010350&flag=1 [11] 林建, 何金海.海温分布型对长江中下游旱涝的影响.应用气象学报, 2000, 11(3):339-347. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20000350&flag=1 [12] 杨明, 徐海明, 李维亮, 等.近40年东亚季风变化特征及其与海陆温差关系.应用气象学报, 2008, 19(5):522-530. doi: 10.11898/1001-7313.20080502 [13] 尚可, 詹丰兴, 何金海, 等.前期夏季西太平洋暖池热含量对江南春雨的影响及其可能机理.海洋学报, 2014, 36(1):86-97. http://www.oalib.com/paper/4848179 [14] 尚可, 何金海, 朱志伟, 等.西太平洋暖池区热含量和海表温度与江南春雨的相关性对比研究.地理科学, 2013, 33(8):986-992. http://www.cnki.com.cn/Article/CJFDTOTAL-DLKX201308014.htm [15] 李超, 徐海明, 朱素行, 等.江南春雨形成机制的数值模拟.高原气象, 2010, 29(1):99-108. http://www.cqvip.com/QK/91655X/201001/33035341.html [16] 张博, 钟珊珊, 赵滨, 等.春季西太平洋海表面温度对我国江南春雨的影响.应用气象学报, 2011, 22(1):57-65. doi: 10.11898/1001-7313.20110106 [17] 陈隆勋, 李薇, 赵平, 等.东亚地区夏季风爆发过程.气候与环境研究, 2000, 5(4):345-355. http://d.wanfangdata.com.cn/Periodical_rdqxxb201405015.aspx [18] 陈隆勋, 张博, 张瑛.东亚季风研究的进展.应用气象学报, 2006, 17(6):711-724. doi: 10.11898/1001-7313.20060609 [19] 张庆云, 陶诗言.夏季东亚热带和副热带季风与中国东部汛期降水.应用气象学报, 1998, 9(增刊Ⅰ):17-23. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=200606120&flag=1 [20] 万日金, 赵兵科, 侯依玲.江南春雨的年际变率及其影响因子分析.高原气象, 2008, 27(增刊Ⅰ):118-123. http://www.oalib.com/paper/4179795 [21] Zhang R H, A Sumi, M. Kimoto.Impact of El Nio on the East Asian monsoon:A diagnostic study of the '86/87 and '91/92 events.J Meteor Soc Japan, 1996, 74:49-62. doi: 10.2151/jmsj1965.74.1_49 [22] Zhang R H, Sumi A, Kimoto M.A diagnostic study of the impact of El Nino on the precipitation in China.Adv Atmos Sci, 1999, 16(2):229-241. doi: 10.1007/BF02973084 [23] 刘屹岷, 刘伯奇, 任荣彩, 等.当前重大厄尔尼诺事件对我国春夏气候的影响.中国科学院院刊, 2016, 31(2):241-250. http://www.cnki.com.cn/Article/CJFDTOTAL-KYYX201602013.htm [24] 邵勰, 周兵.2015/2016年超强厄尔尼诺事件气候监测及诊断分析.气象, 2016, 42(5):540-547. doi: 10.7519/j.issn.1000-0526.2016.05.003