干旱区生态环境知识资源中心

Regional decadal precipitation reconstructions for the and and semi-arid zones of northern China were established by the use of different palaeoclimate archives such as ice-cores, tree-rings, lake sediments and written historical documents. Local rainfall reconstructions from single sites were averaged to obtain regional precipitation records for western and eastern regions of an and and semiarid zone of northern China, respectively. All established regional precipitation curves display 5 dry periods, each lasting about 50 years. Meanwhile, precipitation reconstructions show regional dissimilarities. During the last 500 years, the trends of precipitation change in the eastern and region are basically consistent with those in the western and eastern regions of the semiarid zone. Precipitation variations in the western and region are unique, showing significant local patterns of rainfall variability. Maximum entropy method (MEM) spectral estimates show that each regional precipitation series contains stationary century-scale periodicities of about 120 a. Singular spectrum analysis was applied to isolating the century-scale oscillation signals from the regional proxy precipitation series. Significant periods with wavelengths of 121.4a, 154.6a, 124.3a, 118.6a, 108.5a and 121.4a were found 26.56%, 26.44%, 28.87%, 18.67%, 33.48% and 34.04% of the variances of the original series for the western and zone, the eastern and zone, the whole and zone, the western semi-arid zone, the eastern semiarid zone and whole northern China, respectively.