1948～2001年全球陆地12～2月降水旱涝长期变化

本文利用1948～2001全球陆地月降水资料(PREC／L)，研究了全球、北、南半球及欧亚、非洲、澳洲、北美、南美和南极大陆6个大尺度区域12～2月的降水趋势变化及早涝气候变化。结果表明：全球、南、北半球的12～2月的陆面降水有明显的年代际变化，全球12～2月降水量从1975年开始有明显的下降趋势，回归系数约为-0．017mm／a。北半球有明显的降水减少，约为-0．028mm／a，南半球12～2月降水表现为极微弱的下降趋势，且在统计上是不显著的。划分出了全球、南北半球、全球6个大尺度区域12～2月旱涝年，指出全球及北、南半球12～2月的旱涝有明显的年代际变化。70年代中期以前是全球洪涝多发期，80年代到90年代为全球干旱多发期。北半球旱涝特征与全球特征相近，南、北半球12～2月的旱涝没有明显的联系。12～2月大尺度区域中：欧亚大陆、北美洲、南极大陆旱涝年的分布有明显的年代际特征，并指出全球大部分地区的旱涝年降水量有显著的差异。6个大尺度区域12～2月的降水相关关系中，欧亚大陆和非洲大陆的相关系数最高，为-0．35，北美大陆与欧亚大陆，南美洲和澳洲的12～2月降水也有较高的相关关系。

SECULAR VARIATION OF PRECIPITATION AND CHANGE OF FLOOD /DROUGHT OF GLOBAL LAND IN DEC.-FEB.DURING 1948-2001

Based on global land monthly precipitation dataset PREC/L during the period of 1948-2001, the flood/drought and the secular trend variation of precipitation of global, the Northern Hemisphere (NH) ,the Southern Hemisphere(SH), Eurasia, Africa, Australia, North America, South America and Antarctica in December-February (DJF) are investigated. The results indicate that the precipitation of global, NH and SH experienced decadal change: a minus-trend from 1974s global precipitation for DJF, regression coefficient is -0.017 mm/a. The precipitation of Northern Hemisphere has a significant negative trend, lapse rate of precipitation during DJF is -0.028 mm/a .for the Southern Hemisphere , but it hasn't pass the statistical significance .The flood/drought years are picked out in 1948-2001 for DJF over global, Northern and Southern Hemisphere, six large-scale areas, the results point out there is significant decadal change in the flood/drought years of global ,NH and SH in DJF,during 1940s-1970s global flood in DJF occurred frequently and from 1970s-1990s global drought in DJF occurred frequently. The flood/drought characteristics of Northern Hemisphere are agreed with ones of the global. There is no obvious correlation between the Northern and Southern Hemispheric flood/drought in DJF. Eurasia, North America, Antarctica have significant interdecadal change of the flood/drought during DJF. Global has a significant contrast of rainfall between flood/drought years. The correlations among six large-scale areas precipitation are analysed. Study shows that the relationships of precipitation may exist among the Eurasia and Africa (The correlation coefficients is -0.35), North America and Eurasia , South America and and Australia.