近50年秋季全球旱涝年的分布特征及其与海温和ENSO的关系

Distributional Rule and Feature of Global Dry and Flood Years in Autumn within Past 50 Years

该文用Chen等(2001)最新创建的全球陆地月降水资料(PREC L),划分并检验了1948年～2001年全球9月～11月的旱涝年。结果表明,冷事件大多对应涝年,暖事件大多对应旱年。全球9月～11月降水有明显的年代际变化,涝年大多在80年代以前,旱年大多从80年代开始。其中,1987年～1997年全球9月～11月的连续旱年,是一个非常特殊的时段。指出,印度季风区域、东南亚地区、热带太平洋岛屿、我国的东南沿海及日本一带、西非季风区及墨西哥湾区域,是旱涝年的平均降水差异较大的区域。并指出,东太平洋和西南太平洋3月～5月海温的变化对于9月～11月全球陆地降水的趋势变化有很好的预报意义。划分并检验了南、北半球9月～11月的旱涝年。指出,北半球旱涝年的分布和全球的是基本一致的,南半球与北半球的旱涝年的分布具有明显的正相关。

The global dry and flood year has been identified in this paper by global land monthly data (PREC/L) in September-November during 1948 to 2001. The flood years are 1950, 1952, 1954, 1955, 1956, 1961, 1964, 1970, 1971, 1973, 1974, 1975, 1983, 1986,1998 and dry years are 1948, 1953, 1965, 1968, 1972, 1982, 1987, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1997. Monte Carlo method was used to examine the dividing rationality of dry and flood years. The results indicated the differences of SON mean rainfall of dry and flood years are significant. The relationships between global rainfall in September-November and ENSO events show that the cold events are mostly corresponding to flood years and the warm events are mostly corresponding to dry years. The dryness/flood of the globe in September-November show distinctive decadal changes: the 1950s and 1970s are frequently-occurring periods of SON global floods with five flood years and one dry year, respectively; and the 1980s～2000s is a frequently-occurring period of SON global droughts with 10 dry years and 3 flood years. Because of the continuous flood years, the period of 1987～1997 is very peculiar. It also points out that the are as with distinct difference are Indian monsoon region, southeast of Asia, tropic Pacific islands (south Asia monsoon region), southeast of Australia, coastal regions of southeast China and Japan, west of Africa monsoon region and Mexico bay. And the change of SST in March-May in the east of Pacific and southwest of Pacific will forecast the trend change of global land rainfall in September-November well. The results show that the distribution of dry and flood years of north hemisphere is consistent with the global. And there is obviously positive correlation between the distribution of dry and flood years of north and south hemisphere.