Abstract:

Studying the continuous rain characteristics and atmospheric circulation background during the picking period of ponkan in Quzhou can provide a scientific guide for picking ponkan on time.Based on the daily weather data such as precipitation, rainy days, sunshine hours, relative humidity, etc., this study analyzed the change characteristics of the continuous rain and atmospheric circulation background during the picking period of ponkan from 1951 to 2018 using the statistical analysis and wavelet analysis methods.The results show that the number of consecutive rainy days, frequency, and intensity of rain during the picking period of Quzhou ponkans lightly increase, and the number of rainless days with a 3-day sliding decreases and shows the characteristics of 5 years and 7 years inter-annual and 15 years inter-decadal cyclical changes, and the cycles present a shortening trend.In the strong continuous rainy years during the ponkan picking period, a meridional circulation with two heights and one low prevails over the Asia-Europe region.Under such circumstances, strong cold air moves southward frequently and eastward slowly, and the southerly warm and humid airflow is active, which causes a convergence of warm and cold air in the middle and lower reaches of the Yangtze River for a long time.

Key words: Ponkan picking period, Continuous rain, Atmospheric circulation background