Based on the above principles, Bian Xiao will analyze why there is so much rain this year. According to experts, the average precipitation in the Yangtze River basin this year is 196 1, the highest in the same period in history. Experts say that this is mainly due to the rainy season and the El Ni? o phenomenon. Wang Yongguang, chief forecaster of the National Climate Center, said that it was the plum rains that triggered the continuous heavy precipitation. Specifically, the early arrival of Meiyu and the strong Meiyu front are the reasons for the unusually high rainfall in the Meiyu period in the middle and lower reaches of the Yangtze River. This year, the plum rains in the south of the Yangtze River are seven days earlier than in previous years. Because the South China Sea summer monsoon broke out earlier this year, the ridge of the western Pacific subtropical high was northward in the first half of June, which led to the early arrival of Mei in the middle and lower reaches of the Yangtze River.
In addition, a weak El Nino event occurred last autumn, and the SST in the northern Indian Ocean was unusually warm, which led to the obvious strong subtropical high. At the same time, the meridional circulation develops in the middle and high latitudes, the cold vortex is active, and the cold air erupts strongly in the process of moving to the middle and lower reaches of the Yangtze River. As a result, cold and warm air meet in the middle and lower reaches of the Yangtze River, resulting in a strong Meiyu front and obvious precipitation in the middle and lower reaches of the Yangtze River. So, will extreme weather become more and more frequent in the future? Huang Lei, a researcher at the Climate Change Adaptation Office of the National Climate Center, said in an interview with the Central Meteorological News, "Although it is difficult to directly attribute a single weather and climate event (such as heavy rain in the south) to global warming, some extreme weather and climate events are indeed increasing in the context of global warming."
Taking the facts as an example, since 195 1 year, the average temperature and extreme temperature in China have shown a significant upward trend, and some extreme weather and climate events have the characteristics of stronger intensity, higher frequency and longer duration. At the same time, the climate change assessment report issued by the United Nations Intergovernmental Panel on Climate Change (IPCC) also pointed out that in the 2 1 century, there will be more high temperature and rainstorm events in some parts of the world, and the degree of drought will be aggravated, threatening the food, water resources and energy security of all countries. The prediction results of climate model show that if the emissions of man-made greenhouse gases are not controlled, the frequency, intensity and duration of some extreme events will increase significantly in the future. By the end of February1,the probability of high-temperature heat wave events in land areas will be 5- 10 times as high as it is now, and the frequency of extreme precipitation events in most parts of the world will also increase.