2013年全球重大天气气候事件及其成因

Global Significant Weather and Climate Events in 2013and the Possible Causes

2013年,全球气温持续偏高,与2007年并列为第六个最暖年份,其中气温异常偏高的地区主要位于澳大利亚、北美洲北部、南美洲东北部、非洲北部以及欧亚大陆的大部地区。年内,赤道中东太平洋基本维持弱冷水状态,北极海冰范围仍处于记录中最低水平之一,而南极海冰范围则创历史新高。受大气环流异常以及海洋和海冰等外强迫因子的共同影响,世界范围内出现了显著的气候异常和极端事件,年初寒流和暴风雪袭卷亚洲、欧洲部分地区和北美洲,澳大利亚出现了极端高温天气;6—9月中欧、亚洲和北美洲部分地区遭受暴雨洪涝的袭击,期间北半球大部地区则发生了极端高温天气;6月以来多个强台风袭击东亚、东南亚和北美洲东海岸。分析指出,大气环流异常是上述全球重大天气气候事件的直接原因,而太平洋海温异常通过海气相互作用对大气环流异常产生重要影响。此外,在全球升温的过程中,伴随着气温平均值和变幅增大,致使发生极端天气气候事件的概率增加,这为全球许多国家和地区出现异常天气提供了有利的气候背景条件。

In 2013,above-average temperatures affected most of the global land surface areas.This is the sixth warmest year since records began in 1850,which is the same as 2007,and abnormal high tempera-tures were observed in Australia,northern North America,northeastern South America,northern Africa and most Eurasia.During the year,the weak cold water continually dominated the most of the eastern and central equatorial Pacific,and sea ice extent in the Arctic was still at one of the lowest levels in records, while the Antarctic sea ice extent has reached a new record.Affected by the anomalous atmospheric circu-lation combined with the external forcing factors of ocean and sea ice,notable climate anomalies and ex-treme events occurred worldwide in 2013.In early 2013,extreme cold waves and snowstorm attacked parts of Asia,Europe and North America while Australia experienced extreme high temperatures;from June to September,the Central Europe,parts of the Asia and North America suffered rainstorms and floods, while the hot weather hits the most of the Northern Hemisphere in same period.Since June,tropical storms and hurricanes attacked the East Asia,Southeast Asia and the east coast of America.The analysis results show that atmospheric circulation anomalies are the main causes for the above global extreme weather and climate events,and the Pacific sea surface temperature anomalies contribute to the atmospher-ic circulation anomalies by air-sea interaction.In addition,during the process of global warming,the aver- <br> age temperature and its amplitudes of variation are all increasing,resulting in the increase of the frequen-cies of extreme weather and climate events,which has provided the favorable conditions for the occurrence of abnormal weathers in many countries and regions of the world.