The Variations Of The Cold-warm And The Drought-flood During The Recent 50 Years In Heilongjiang Province

In this paper, based on the Wavelet Theory which is considered an important breakthrough to Fourier Analysis, the variations of air temperature and precipitation during the recent 50 years in Heilongjiang Province have been analysed using the Morlet wavelet transformation method. Wavelet transformation with Fourier power spectral analysis are compared. The results are as follows: ?The temperature variations in Heilongjiang Province appear the multi-time scale and jump characteristics. There are obvious 10-20 years and 40-55 years decades scale periodic changes and 1 year, quasi-biennial, 4 years and 6-8 years annual scale ones in Heilongjiang's temperature variations. The 40-50 years periodic change divides the temperature variation into three main cold and warm vicissitudes of the last 50 years, which include the warm period before mid 1960s, the cold period from later 1960s to 1980s and the warm period after the 1980s; (2) The precipitation variations in Heilongjiang Province have multi-time scale and jump characteristics. There are obvious 10-15 years and 25-40 years decades scale periodic change and 1 year, 2 years and 4 years or so annual scale periodic change in Heilongjiang's precipitation variations. For example, the jump points that 8 years converging upon 1 year are in 1958, 1970, 1981 and 1998. (3) Though the conventional Fourier power spectral analysis can reflect the common characteristics of the signal, it cannot provide the fine structure of time-frequency changes and the location of the jump points, while the wavelet transforming can better the situation.Secondly, the correlations between El Nino Southern Oscillation(ENSO) with the temperature and precipitation during the recent 50 years in Heilongjiang are analysed by the bivariate wavelet transformation applying Marr wavelet function. And some comparisons are made by applying both bivariate wavelet transformation and Fourier cross spectral methods to the data. The results show that the correlations between E1 Nino and the temperature and precipitation in Heilongjiang Province have multi-time scale characteristics; (1) The correlations between SST in NINO3 and temperature in Heilongjiang Province are negative as a whole, but their correlations are evidently different according to different time scales; the correlations between the temperature and Southern Oscillation Index (SOI) are positive in annual-scale periodic changes and negative in decades periodic changes. (2) It shows strong positive correlation at 32 years periodic scale between the precipitation and SST in NINO3, while the periodic characteristics are more distinct at 4 years though it is mostly positively correlative then; In a shorter time scale period, the correlation between the precipitation in Heilongjiang and SOI is the regular transforming of positive and negative correlations, while at a longer annual or decades scale, the correlations, though mostly negative, are periodically positive.The article analyses the time-frequency characteristics of the main climatic elements in Heilongjiang Province more particularly, and discusses the main regularity of the climatic variations in Heilongjiang Province, The conclusions obtained are of referential importance for they can provide the background and main features of climatic changes in short-term climate forecast for Heilongjiang Province and the Northeast areas in our country.