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.