Annual precipitation fields secular variation over global land areas for 1948—2000

In contrast to global temperature, fewer studies have been contributed to global precipitation. There are nu-merous efforts devoted to the problem, including Gruza1], Diaz et al.2], Bradley et al.3], Vinnikov et al.4] and Hulme5], in which the global precipitation was addressed simply in the context of data in the 1980s, sometime be-fore that and the early 1990s6—8]. More recently, studies have involved data around 1997 but on a local basis. Evi-dently, the problem of secular variatio…

Annual precipitation fields secular variation over global land areas for 1948–2000

The secular variation over the global land annual precipitation (GLAP) fields for 1948-2000 is investigated. Evidence suggests that the GLAP abruptly reduced around 1978 and experienced a decrease of 0.54 mm/a, on average. Fuzzy clustering is used to group the annual precipitation over commonly-used 36 latitudes belts into six belts for examining its secular variation. The results show that, except northern high-latitudes (60°-90°N) where it is slightly increased, the precipitation is decreased, especially in 35°N-35°S, and the diminution is the maximum of 0.98 mm/a at tropics. Moreover, identification of 1948-2000 flood/drought years on a global basis is made, showing noticeable interdecadal variations. During the years of warm (cold) events the precipitation decreases (increases) by 15.4 mm (14.4 mm) per year, on average. It can be assumed that global warming and frequent ENSO occurrences from the end of the 1970s maybe serve as the root cause of the diminution.