Why do El Nino and La Nina make the summer in northern China hot and dry?

El Nino has a serious impact on our climate. First, the number of typhoons has decreased. After the El Ni? o phenomenon, the number of tropical storms (typhoons) in the northwest Pacific and the number of landings in China's coastal areas are less than normal. Secondly, the northern part of China is prone to high temperature and drought in summer. Usually in El Nino, the summer monsoon in China is weak, and the monsoon rain belt is south, which is located in the middle of China or south of the Yangtze River. Drought and high temperature often occur in summer in northern China. 1997 After the strong El Ni? o, the drought and high temperature in northern China were very obvious.

Impact of La Nina on China's climate: This year is in La Nina state, that is, the SST in the equatorial eastern Pacific is 0.5 degrees lower than normal, which has a very obvious impact on China's climate. Under the influence of La Nina phenomenon, the meridional circulation in East Asia is abnormal, which is very beneficial to the southward movement of cold air in northern China. It has given us a cold winter, so we can see that this cold winter has already appeared this year. Since 2008, the high pressure in Asia has been very active, forming a cold air mass in the south, affecting China and causing large-scale gale and cooling weather. However, due to the active warm air mass in the south this year, a large number of warm and humid air currents from the Pacific Ocean and the Indian Ocean frequently patronize the southern region. When the powerful cold air mass from Mongolia and Siberia quickly moved south to meet the warm and humid air mass, the cold and warm air just merged into one. Affected by these two air currents, there have been more rainy and snowy weather recently, especially in the Yangtze River basin, and the low temperature weather has lasted for a long time. If there is only a strong cold air mass without a large amount of water vapor provided by warm and humid air mass, there will only be strong winds and cool weather in the south; If there is only a large amount of water vapor provided by warm and humid air masses, there will be no disastrous weather at all without the arrival of cold air masses. When both are ready, disaster comes.