The Study On The Change Characteristics Of Sea Surface Temperature Based On The Wavelet Analysis

Under the circumstances of global warming,there is a certain degree of rise inthe global Sea Surface Temperature (SST). The change of SST not only determinesthe survival environment of marine life but also influences the living and productionof mankind, as well as the development of economy and society. Accordingly,Thestudy on the evolution characteristics of SST and discussion on its various situationsin large, medium or small scale of period could provide effective reference data on theglobal climate and weather forecast. Meanwhile, it also has the vital significance onthe prediction of the temperature change of coastal cities, for instance Qingdao, andthe development of tourism economy. Wavelet transform analysis, one kind ofmathematical analysis method, was developed in the1980s. With respect to theunsteady data signal, the wavelet is able to present its changes in different scales oftime clearly.This paper analysed the various characteristics of SST data from1880to2011inthe software environment of MATLAB, with Mexico hat wavelet and Morlet Waveletas the wavelet base and one-dimensional continuous wavelet transformed, and thenacquires the various characteristics and periodic law of SST in the large, medium andsmall scale of period. By analysing the change features of the temperature of Qingdao,the uniformity of change features is obtained between the Qingdao temperature andsea surface temperature.The principal research contents of this paper are shown as follows:(1) The trend analysis of SST. After the analysis on the various characteristics ofSST data from1880to2011, it is witnessed that the value of SST has undergone anincreasing trend in general during this132years. Specifically, it experienceddecrease first, and then increase. Next, reduce again and subsequencely rise up.(2) The study on the change features of SST. This paper acquires the changefeatures of SST, not only globally but in both hemispheres, by means of wavelettransform method. It is found that SST usually has a scale of warm center from80to 100years and approximately40-year unclosed cold center in large scale; however,in small and medium scale, the change of SST is frequent.(3) Using wavelet variance figure to investigate SST cycle. Through the analysisof wavelet variance figure, it is summarized that the interdecadal cycle of around80and40years is all existed both in the globe and in the north and south hemispheresin large scale, and the energy of wavelet variance visualizes bimodal type.(4) Analyzing the change trend of Qingdao temperature and research on itschange features and periodic law in the medium and small scales. It is concludedthat Qingdao’s temperature has experienced a rise trend during the recent51years,the time of the appearance of the lowest and highest anomaly is4years later thanSST. The temperature of Qingdao goes through four partial warm periods and threepartial cold periods in the scale of10to20years and it changes frequently in thescale of less than10years. Based on the analysis of wavelet variance figures, thispaper obtains a12-17years of change cycle in medium scale and a4years of changecycle in small scale. The change trend, characteristics and cycle of temperature has abetter consistency with sea surface temperature.