印度洋暖池热含量变化对低纬高原汛期降水的影响

 利用美国Scripps海洋研究所提供的1961—2003年的海洋热含量再分析资料、低纬高原148站降水资料和NCEP/NCAR环流再分资料，采用EOF分析、相关分析、合成分析等方法研究了印度洋暖池热含量变化，及其对低纬高原6—8月降水的影响及其可能原因.结果表明，印度洋暖池6—8月热含量变化E0F分析第1模态为全场一致型，解释方差为28%.印度洋暖池热含量与中国低纬高原6—8月降水的关系主要体现为与云南北部和东部等地区的显著正相关，这种相关关系源于前期2—4月，且随时间的推移其影响范围不断扩大，至同期时达到最好.在印度洋暖池热含量偏高年，暖池区持续的加热异常在东侧对流层低层激发出反气旋式环流异常，造成副高西伸，从而在副高外围形成一条自孟加拉湾向低纬高原区域的经向水汽输送带，为低纬高原区域输送大量的水汽，从而造成低纬高原区域降水增多.相反，在印度洋暖池热含量异常偏低时，西南风水汽输送带较弱，水汽输送无法穿越山脉输送到低纬高原区，造成低纬高原汛期降水偏少.
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On the influence of north Indian ocean warm pool thermal content variation on Low Latitude plateau summer precipitation

Based on the reanalyzed thermal content data from American Scripps Sea Research Institute,the monthly precipitation data of the Low Latitude Plateau,and NCEP/ NCAR reanalysis data from 1961 to 2003,the relationship between Indian Ocean warm pool (IOWP) thermal content and Low Latitude Plateau (LLP) precipitation form June to August has been studied by using the empirical orthogonal function (EOF) methods,correlation analysis and composite analysis.Results of EOF analysis of Indian Ocean warm pool thermal content show that the EOF1 mode,which accounts for 28% of total variance,consistently represents variations of thermal content over Indian Ocean warm pool.The Low Latitude Plateau summer precipitation is notably influenced by Indian Ocean warm pool thermal content.When the IOWP thermal content is in a high (low) phase,the continuous heating of the IOWP can evoke anti-cyclonic circulation anomaly and cause the subtropical high extent to west,enhancing meridional water vapor transport band along the periphery of subtropical high from the Bengal Bay to the Low Latitude Plateau and resulting in more rainfall in northern and eastern LLP.By contrast,when the IOWP thermal content is low,the southwest water vapor transport band is weak; hence the water vapor cannot prevail to Low Latitude Plateau,leading to less rainfall there in summer.