2019年全球重大天气气候事件及其成因

Global Major Weather and Climate Events in 2019 and the Possible Causes

2019年全球主要温室气体浓度继续保持上升趋势,全球平均温度比工业化前水平高1.1(±0.1)℃,为有气象记录以来第二暖年。海洋热容量及海平面高度创新高,海冰面积偏小。年内,全球各地发生了许多重大天气气候事件,包括多地遭遇暴雨洪涝侵袭,澳大利亚以及亚洲和欧洲多国受干旱影响,全球极端热带气旋频发,欧洲及澳大利亚等地遭遇异常高温热浪天气,北美和欧洲遭受寒流和暴风雪袭击,多地出现强对流天气。分析表明,印度洋偶极子(IOD)处于正位相、赤道中太平洋地区海温持续偏暖以及副热带高压系统控制是澳大利亚高温少雨的主要原因,最终引发严重的森林山火;前期异常偏强的IOD正位相叠加持续时间异常偏长的热带低压,促进了2019年印度7—8月强暴雨事件的发生发展。

The global concentration of major greenhouse gases continued to rise in 2019,and the global average temperature in 2019 was 1.1(±0.1)℃higher than the pre-industrial level,being the second warmest year on record.The ocean heat content and sea level height have reached new high levels,while the sea-ice extent was at a low-level.Many significant weather and climate events occurred in 2019,including torrential rains and floods in many places,droughts in Australia and many countries in Asia and Europe,frequent extreme tropical cyclones,unusually high temperature and heat waves in Europe and Australia,cold and heavy snowstorms in North America and Europe,as well as severe convective weather in many regions.The positive phase of the Indian Ocean dipole(IOD),the continuous warming of the sea surface temperature in the equatorial central Pacific and the control of the subtropical high pressure system were the main causes of high temperature and little rain in Australia,resulting in serious forest fires.The continuous heavy rainfall in India from July to August was mainly due to the abnormally strong positive phase of IOD and the tropical depression with unusually long duration.