Decadal Characteristics of Global Land Annual Precipitation Variation on Multiple Spatial Scales

Based on 1951-2010 Global Precipitation Climatology Centre monthly precipitation dataset, decadal characteristics of annual precipitation over the globe, the Eastern and Western Hemispheres, five continents and four typical arid and semi-arid regions were analyzed using the Ensemble Empirical Mode Decomposition (EEMD) method. The results showed that: (1) there exists a decadal oscillation in global land precipitation in addition to a long-term trend. Compared to the long-term trend, the decadal oscillation is more distinct and it is the major phenomenon in global land precipitation. (2) On the hemisphere scale, decadal characteristics of the Eastern and Western Hemispheres are opposite before 2000, with a drying trend over the Eastern Hemisphere and an wetting trend over the Western Hemisphere. (3) The decadal oscillation, long-term trend, drying period and drought period of precipitation over Eurasia and Africa exhibit an opposite variation with that over North America, South America and Australia during 1951-2010. Five continents tend to enter a wet phase in the recent 10 years. (4) The decadal characteristics of precipitation over the four typical arid and semi-arid areas have distinctly differences. Generally, the long-term trend and multi-decadal oscillation of precipitation over North China and North Africa are opposite with that over North America and central Asia. North China and North Africa are approximately in phase. Although North America and central Asia are both in wet period in the recent years, the beginning year for the wet period is 1975 in North America and 1985 in central Asia. Additionally, North America experiences a dry period during the first wet period (1959-1968) in central Asia.