The secular variation over the global land an-nual precipitation (GLAP) fields for 1948—2000 is investi-gated. Evidence suggests that the GLAP abruptly reduced around 1978 and experienced a decrease of 0.54 mm/a, on ...The secular variation over the global land an-nual precipitation (GLAP) fields for 1948—2000 is investi-gated. 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 pre-cipitation 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 no-ticeable 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 dimi-nution.展开更多
文摘The secular variation over the global land an-nual precipitation (GLAP) fields for 1948—2000 is investi-gated. 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 pre-cipitation 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 no-ticeable 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 dimi-nution.
