近百年长江下游作物生长季冷暖的变化与大型环流的振动

本文运用上海1373—1982年110年气温资料,配合1871—1980年110年月平均海平面气压场资料,分析了长江下游作物生长季冷暖的长期变化以及与之关联的大型环流变化特征。发现最近百余年里,年、季(代表月份)和关键旬的平均气温普遍经历了从偏冷期转为偏暖期约80—100年周期的振动,转折发生在本世纪20年代末、30年代初。70年代前后有转向偏冷期的趋势。这类低频振动与大型环流活动的低频振动有密切关联,主要表现在冬季亚洲大陆冷高压主体偏东和阿留申低压偏弱时期,相应夏季青藏高原热低压偏弱时期,对应长江下游偏冷期;反之,则对应偏暖期。讨论了生长季冷暖变化对农作物生长发育和产量的影响。

COLD/WARM CHANGE OF LOWER YANGTZE DURING THE CROP GROWING SEASON IN THE LAST 100 YEARS AND THEIRRELATION TO LARGE-SCALE CIRCULATION FLUCTUATION

Using both data of temperature in Shanghai during 1873-1982 and of rnonthly mean sea-level pressure field over the Eastern Hemisphere during 1271-1980, the inversion of the colder/warmer patterns of the Lower Yangtze during the crop growing season are analyzed by associating with the evolution feature of the large-scale circulation. The main results are as follows: 1,For more than century lately, the yearly, representative monthly of seasons and key decadely mean temperatures run widely through a 80-100 years periodic fluctuation in which the colder term inverted the warmer term. It is an inversion point in the late 20's or early 30's of the 20th century. Since 70's it seems running to the colder term. 2, The inversion of the colder/warmer terms is correlated with the low-frequency fluctuation of the large-scale circulation. Summarily when the main place of Asian Continent colder-high pressure is Basting and Aleutian low pressure is weaker in winter, and Tibetan Plateau hotlow pressure is weaker in summer, corresponding to the colder term. In reverse, there is the warmer term.