中国春季土壤湿度与东亚夏季风的关系
A STUDY ON THE RELATIONSHIP BETWEEN SPRING SOIL MOISTURE OVER CHINA AND EAST ASIA SUMMER MONSOON
-
摘要: 利用1981～2002年全国土壤湿度资料,利用相关分析发现东亚夏季风和河套地区及西南地区春季土壤湿度之间存在较大的正相关,利用这两个区域的春季土壤湿度定义了一个标准化春季土壤湿度指数(SMI),结果发现:(1)SMI和东亚夏季风的强弱相关较好。高指数年东亚季风区低空西南夏季风气流和高层东风气流明显偏强,表明这一年夏季风偏强,低指数年则相反;(2)强SMI年,西太平洋副热带高压位置偏北,强度偏弱,西风扰动带偏北,有利于夏季风北推,不利于北方冷空气南下与之交汇,使得锋区偏北,位于华北、东北地区。弱SMI年则反之;(3)SMI能够较好地反映东部地区夏季降水,在强SMI年,长江流域降水明显偏少,而华北和河套地区的降水明显增多,而弱SMI年正好相反,这与东亚夏季风降水的环流形势也较为吻合(;4)SMI指数存在明显的4～6年和准2年的周期振荡,但其振幅和周期又有明显的周期变化。在对东亚夏季风强度的预报能力上,负的SMI对弱东亚夏季风的预报能力要强于正SMI对强东亚夏季风的预报能力。Abstract: The correlation analysis was used to study the relationship between spring soil moisture over China and East Asian summer monsoon(EASM).It is shown that EASM has a strong positive correlation with spring soil moisture over southwest China and the Great Bend region of the Yellow River.A standard soil moisture index(SMI) was defined using the observed soil moisture of the two regions.The results show that SMI has a strong correlation with EASM.The years of strong(weak) SMI are associated with stronger(weaker) summer monsoon circulation.In the years of strong SMI,the west Pacific subtropical high is much northward in position and weaker in intensity;the westerlies zone is also more to the north.All of these make EASM circulation move northward and cause the rainfall belt to relocate to North China and Northeast China.SMI can reflect the variation of the summer rainfall anomaly over eastern China.In the years of strong SMI,the rainfall belt is mainly located over the northern part of China.However,during the weak years,the summer rainfall belt is largely located over the mid-and lower-reaches of the Yangtze River.Additionally,the SMI has obvious oscillations of quasi 4～6 years and quasi 2 years.Moreover,negative SMI predicts EASM better than positive SMI.
-
Key words:
- soil moisture /
- East Asia summer monsoon /
- summer rainfall /
- prediction ability
-
[1] NAMIAS J.Persistence of mid-tropospheric circulations between adjacent months and seasons[M].Rossby Memorial Volume,Oxford:Rockefeller Institute Press and Oxford University Press,1958:240-248. [2] NAMIAS J.Surface-atmosphere interactions as fundamental causes of droughts and other climatic fluctuations[M].Arid Zone Research,V20.Changes of Climate Proc 0f Rome Symp,UNESCO.75700 Paris,France,1963:345-359. [3] MANABE S.Climate and ocean circulation,Ⅱ:The atmospheric circulation and the hydrology of the earth's surface[J].Mon Wea Rev,1969,97(11):739-774. [4] MANABE S,SMAGORINSKY J,STRICKER R J.Simulated climatology of a general circulation model with a hydrological cycle[J].Mon Wea Rev,1965,93(12):769-798. [5] HENDERSON-SELLERS A.Soil moisture:A critical focus for global change studies[J].Global and Planetary Change,1996,13(1):3-9. [6] 孙岚,吴国雄.陆面蒸散对气候变化的影响[J].中国科学(D辑),2001,31(1):59-69. [7] VINNIKOV K YA,YESERKEPOVA I B.Soil moisture:Empirical data and model results[J].J Climate,1991,4(1):66-79. [8] VINNIKOV K YA,ROBOCK A,SPERANSKAYA N A,et al.Scales of temporal and spatial variability of midlatitude soil moisture[J].J Geophys Res,1996,101:7 163-7 174. [9] DELWORTH T L,MANABE S.The influence of potential evaporation on the variabilities of simulated soil wetness and climate[J].J Climate,1988,1:523-547. [10] 李国平,符淙斌,叶笃正.大尺度降雨异常对地面过程的影响——一类气候反馈机制的初步研究[J].大气科学,1991,15(2):23-31. [11] 刘永强.土壤湿度和植被对气候影响的研究[D].中国科学院大气物理研究所博士论文,1990. [12] 马柱国,魏和林,符淙斌.中国东部区域土壤湿度的变化及其与气候变率的关系[J].气象学报,2000,58(3):278-287. [13] 孙秀荣,陈隆勋,何金海.东亚海陆热力差指数及其与环流何降水的年际变化关系[J].气象学报,2002,60(2):164-172. [14] 高辉,张芳华.关于东亚夏季风指数的比较[J].热带气象学报,2003,19(1):79-86. [15] 陈隆勋,朱乾根,罗会邦,等.东亚季风[M].北京:气象出版社,1991:78-80. -
点击查看大图
计量
- 文章访问数: 1112
- HTML全文浏览量: 0
- PDF下载量: 805
- 被引次数: 0
下载:
粤公网安备 4401069904700003号