Large scale heavy rainfall in the south continues! What impact will El Ni ñ o bring to our country?, Many northern regions are experiencing high temperatures and "grilling" El Ni ñ o | floods | China

Recently, many areas in the north have been hit by high temperatures, with temperatures above 37 ℃ affecting an area of approximately 450000 square kilometers. 21 national meteorological stations in Beijing, Tianjin, Hebei, Shandong and other areas have seen their daily highest temperatures exceed historical extremes; Large scale heavy rainfall continues in the southern region, with a rainfall coverage area of over 100 millimeters reaching 205700 square kilometers.

Since this summer, many parts of the Northern Hemisphere have been experiencing extreme high temperatures. Why do extreme weather occur frequently? What impact will the developing El Ni ñ o have on our country?

Since June, the sea surface temperature in the equatorial central eastern Pacific has significantly increased and has now entered an El Ni ñ o state. According to the National Climate Center's prediction, the equatorial central and eastern Pacific will maintain an El Ni ñ o state in the next three months, with a continuous increase in sea surface temperature index, and a moderate to strong eastern type El Ni ñ o event will form in the autumn of this year.

Experts suggest that in the context of global warming, the combination of moderate to high intensity El Ni ñ o events may lead to more frequent, wider, and stronger extreme weather events.

Since 1951, there have been a total of 21 El Ni ñ o events in the equatorial central and eastern Pacific, which have had an impact on China, including high temperatures, heatwaves, floods, and droughts.

For example, in the summer of 2006, affected by El Ni ñ o, Chongqing, eastern Sichuan, western Hubei, southern Shaanxi and other places experienced rare and sustained heatwaves. The National Climate Center analyzed historical data and found that during the summer of the El Ni ñ o development year, the air temperature in southern North China, central and northern China, central and eastern East China, and eastern Northwest China is prone to high temperatures, with some areas experiencing over 30 days of high temperatures.

"In the summer of the El Ni ñ o development year, the subtropical high pressure in the western Pacific tends to be southward and stronger, causing more precipitation in the southern region of China. The recent frequent occurrence of heavy rainfall in Jiangnan, South China and other areas is one of the manifestations of the impact of the El Ni ñ o state," said Zhou Bing, Chief Expert of Climate Services at the China Meteorological Administration.

Meanwhile, the southward and stronger subtropical high pressure is not conducive to the movement of rain bands during the flood season. From the 1998 Yangtze River Basin flood, it can be seen that it was precisely because the entire rain belt continued to flow around the Yangtze River during the flood season, leading to the formation of a "peak to peak" pattern in the Yangtze River flood.

After the occurrence of El Ni ñ o, the eastern part of China is prone to a precipitation distribution pattern of "less in the north and more in the south" in autumn and winter, and the phenomenon of urban waterlogging in the south is prominent, increasing the probability of a "warm winter". Due to the relatively low precipitation in the north, drought is prone to occur. For example, in 2002, there was a continuous summer and autumn drought in some areas of North China and the Yellow and Huai Rivers, in 2006, there was a large-scale autumn drought in the central and eastern regions, and in 2018, there were periodic droughts in areas such as the Yellow and Huai Rivers.

According to the prediction of the National Climate Center, in the context of the strengthening of El Ni ñ o development, it is expected that the southeastern, central and southern parts of China, as well as the southern parts of Southwest China, will experience more precipitation this summer, with a higher risk of flooding; The eastern part of the northwest region is prone to less precipitation, and there is a high possibility of meteorological drought.

Zhou Bing reminds us that the precipitation in the southern region is increasing, and we need to be alert to the occurrence of waterlogging in southern cities.

For agricultural production, recent precipitation in the southern region has been beneficial for increasing and storing soil moisture in most areas of farmland, as well as agricultural water storage. However, it may also cause waterlogging disasters in some areas of farmland and early rice "washing the flowers with rain" during the flowering period. Experts suggest early dredging of ditches and channels, and timely cleaning and drainage of ditches during rainfall intervals; The early rice production areas with high risk of rain washing the flowers need to be sprayed with pesticides and fertilized in a timely manner according to the growth situation to improve the stress resistance of early rice.

In response to the possibility of periodic high-temperature heatwaves, Liu Yanxiang, Chief Public Service Officer of the Public Meteorological Service Center of the China Meteorological Administration, pointed out that high-temperature weather may lead to heatstroke and heat stroke, and increase the risk of cardiovascular and cerebrovascular diseases. It is recommended that the public take good sun protection measures when going out, and outdoor workers should try to avoid working during direct sunlight hours. The relevant departments should do a good job in ensuring energy supply during peak summer periods.

This summer, China may experience regional meteorological droughts. Gao Hui, the chief forecaster of the National Climate Center, suggested that we should seize favorable weather conditions and carry out artificial rain enhancement operations in a timely manner, strengthen the water storage and retention work of Tangba Reservoir, and actively divert and lift water to resist drought.

Experts say that the factors affecting China's climate anomalies, especially extreme events such as high temperatures, droughts, and floods, are complex, and El Ni ñ o is just one of the important factors. For example, during the summer of the same year as the development of El Ni ñ o, the temperature in China was significantly lower in 2004, which is not consistent with the regular understanding. This indicates that the impact of El Ni ñ o on China's climate is somewhat uncertain. The meteorological department will closely monitor and strengthen the analysis and prediction of weather and climate trends.