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| 中国春季土壤湿度与东亚夏季风的关系 |
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乐益龙1,2, 罗勇3, 郭品文1
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1.南京信息工程大学大气科学系, 江苏, 南京, 210044;2.宁波市气象台, 浙江, 宁波, 315012;3.中国气象局国家气候中心气候研究开放实验室, 北京, 100081
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| 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。 |
| 关键词: 土壤湿度 东亚夏季风 夏季降水 预报能力 |
| DOI： |
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| 基金项目:国家自然科学基金项目(批准号:40375026和40331010)资助 |
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| A STUDY ON THE RELATIONSHIP BETWEEN SPRING SOIL MOISTURE OVER CHINA AND EAST ASIA SUMMER MONSOON |
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LE Yi-long1,2, LUO Yong3, GUO Pin-wen1
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1.Nanjing University of Information Science & Technology, Nanjing 210044, China;2.Ningbo Meteorological Observatory, Ningbo 315012, China;3.Laboratory for Climate Studies, National Climate Center, CMA, Beijing 100081, China
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| 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 |