Research on temporal and spatial change of 400 mm and 800 mm rainfall contours of China in 1961-2000

Based on daily precipitation data from 1961 to 2010, the spatial location of 400 mm and 800 mm rainfall contours were quantitatively analyzed via weighted contour line average location. Time series analysis methods such as Kendall, Morlet wavelet, moving t test and Yamamoto method were utilized to systematically reveal the spatial shift feature of 400 mm and 800 mm rainfall contours of China in the recent 50 years: During 1961 to 2010, weighted 400 mm and 800 mm rainfall contours average location were 106°07'12"E, 39°25'13"N and 110°16'31"E, 34°12'04"N. The trendy results showed that 400 mm and 800 mm rainfall contours of China had a shifting trend toward west and south, of which 400 mm rainfall contour had a significant shifting trend toward west and 800 mm rainfall contour had a significant shifting trend toward south. Periodic results indicated that primary period of 400 mm rainfall contour's radical and zonal shift were 9 a and 12 a respectively in China, while that of 800 mm rainfall contour's radical and zonal shift were both 7 a. The breakpoint of 400 mm rainfall contour's spatial location were 1995 to 1996 (zonal) and that of 800mm rainfall contour's spatial location were 1975 and 2002 (radical) and 1980, 1982, 1987(zonal).