Global Significant Weather and Climate Events in 2013 and the Possible Causes
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 temperatures 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 circulation combined with the external forcing factors of ocean and sea ice, notable climate anomalies and extreme 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 atmospheric circulation anomalies by air sea interaction. In addition, during the process of global warming, the average temperature and its amplitudes of variation are all increasing, resulting in the increase of the frequencies 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.