Evolvement of climate-productivity over China Loess Plateau

By applying empirical orthogonal function(EOF),rotated empirical orthogonal function(REOF),complex empirical orthogonal function(CEOF)and wavelet analysis on 1961-2000 weather datum of China loess plateau and 1937-2004 datum of Xifeng station,the spatial and temporal variations of China loess plateau climate-productivity were investigated.The results showed that the climate-productivity kept decreased over China loess plateau.The highest climate-productivity was in 1930s to 1940s,the high was in 1960s.The lowest was in 1990s,the lower in 1980s.The climate-productivity obviously decreased during 1951-1960 and 1978-2000,especially so in 1978-2000;the curve continuously went up during 1961-1978 and stayed growing after 2000.By using wavelet analysis,there were kinds of periods of climate evolvement,the 4 years period was more remarkable.Three divisions,the west,east and south part were identified,showing strong temporal variability.The west part of divisions was unsteady and low yield of climate-productivity,the south part was steady and high yield,the east part was astatic.The sensitivity of the climate-productivity variation was in the north-central plateau.The variation information of the climate-productivity flowed from the east-center area to east south of the plateau.