两类ENSO事件对中国东部地区极端降水的影响

Impact of Two Types of ENSO Events on the Extreme Precipitation in Eastern China

利用1979～2010年中国地区降水数据和IRESST全球海温数据,对比研究了东部型和中部型El Ni1o/La Ni1a事件成熟期至衰退期(冬季至次年夏季)对中国东部地区极端降水和一般降水的影响,进而揭示在两类ENSO事件影响中国东部地区降水时,极端降水和一般降水各自所占的比重。结果表明:极端降水在冬、春和夏季均占总降水量的1/2以上,其中冬季所占比重最高,夏季最低,而且长江以北比长江以南高。当两类ENSO事件发生时,中国东部地区极端降水异常空间分布特征与该地区总降水基本一致,而该地区一般降水异常分布特征则与总降水和极端降水显示出较大差别,表明两类ENSO事件均是主要通过影响极端降水异常来影响到我国东部地区的总降水异常分布。从两类ENSO事件对比来看,东部型ENSO对中国东部地区极端降水的影响要显著强于中部型ENSO,而且在各季节,两类ENSO事件影响下极端降水的空间分布特征也有所不同。在此基础上,分析了1979～2010年4次最强ENSO事件对于中国东部地区极端降水的影响,结果发现,最强ENSO事件对极端降水的影响也是远强于一般降水,而且极端降水异常分布特征与总降水异常基本一致,但是当最强ENSO事件发生时,中国东部地区极端降水和总降水的异常变化较一般ENSO事件更剧烈。

Using the daily precipitation data in China and the IRESST global sea surface temperature data during1979-2010,the effects of the Eastern-Pacific and Central-Pacific El Ni1o/La Ni1 a events on the extreme precipitation and the general precipitation events in eastern China during the period from maturity to recession were studied to reveal the proportion of the extreme precipitation and general precipitation of the total influencing by the two kinds of ENSO events. The results show that,the extreme precipitation accounts for more than half of the total precipitation in winter,spring,and summer,which proportion is the biggest in winter and smallest in summer. Besides,the proportion that the extreme precipitation accounts for in the north of the Yangtze River is higher than that in the south of the Yangtze River. Furthermore,when the two types of ENSO occur,the spatial distribution characteristics of the extreme precipitation anomalies in eastern China are basically consistent with that of the total precipitation anomalies in the region. However,the features of the general precipitation anomalies in this area show a large difference from those of the total and extreme precipitation. The above shows that the two types of ENSO events affect the distribution feature of total precipitation anomalies in eastern China mainly through affecting the extreme precipitation anomalies. From the comparison of the two types of ENSO events,the effect of the Eastern-Pacific ENSO on the extreme precipitation in eastern China is significantly stronger than that of the Central-Pacific ENSO. In addition, under the influence of two types of ENSO events, the distribution characteristics of the extreme precipitation are also different. On this basis,the impact of the four strongest ENSO events during the period of 1979-2010 on the extreme precipitation in eastern China are analyzed. It turns out that the influence of the strongest ENSO events on the extreme precipitation is also much stronger than that of the general precipitation,and the anomalous distribution features of the extreme precipitation are basically consistent with the total precipitation anomalies. However,when the strongest ENSO events occur,the abnormal magnitude variation of the extreme precipitation and total precipitation in eastern China are greater than that of the general ENSO events.