Studies On The Fluctuation Patterns And Charateristics Of Spatial Distribution Of The Winter Chilling Damage In Guangdong

In order to provide scientific advice for wintertime agricultural production in Guangdong Province, we analyzed and studied the yearly variations and spatial distribution of the winter chilling damage in Guangdong for the latest 44 years by using mean daily temperature and daily minimum temperature of 22 Meteorological Stations in Guangdong from December, 1957 to February, 2001.The harmfulness caused by the low temperature in wintertime to the main tropic and south subtropic crop and fruit was discussed and summarized. The climatic change of wintertime air temperature in Guangdong was studied. The result shows that while winter mean air temperature in Guangdong has a rising tendency, its range of oscillation is enlarged. Based on those, the concept of chilling process was put forward according to the lowest biologic temperature of main tropic and south sub tropic crop and fruit in Guangdong and the low temperature (environment temperature 5. 0 ) which is harmful to those crop and fruit . With the lowest air temperature (the daily lowest air temperature) X1, the lasting days of low temperature X2 and an integrative physical element --negative accumulated temperature X3 in which the effect of the intense and lasting days of low temperature were considered, the correlation coefficient of those indexes were calculated and analyzed, and the resultsshowed that there are apparent linear correlations among them.PCA of X1, X2and X3 successions was done, and from these three eigenvector fields, a principal component that its physical meaning is clear and its variance deficiency contribution rate is large (over 75 %) is found. And that principal component was defined as an integrative chilling damage index.The integrative chilling damage index successions of 22 representative stations for 44 years were calculated. Let those successions consist of a matrix. Do EOF to the matrix and get two meaningful eigenvector fields, and therefore two main patterns about the spatial distribution of winter chilling damage in Guangdong was found: the whole distribution pattern and the south-north distribution pattern.A wavelet analysis was made to the wintertime integrative chilling damage index, time-coefficients of the first characteristic vector field and the second eigenvector field of wintertime integrative chilling damage index. The results showed that the whole distribution pattern of winter chilling damage in Guangdong had quasi-8 year periodic variation, and the south-north distribution pattern had quasi-22 year periodic variation. Generally speaking, the periodic variation of winter chilling damage in Guangdong had quasi-8 year mainly oscillation.