Why are there so many droughts this year? Expert: the drought may continue

Recently, high temperature weather has appeared in most parts of the north, which further aggravates the soil water evaporation and leads to the rapid spread of drought. Meteorologists believe that drought or waterlogging is more common in some parts of China in summer. At present, there is no large area drought in the main grain producing areas, but the grain yield in some areas with severe drought is greatly affected.

A peasant proverb says, "there will be drought and flood on July 15th and harvest on August 15th." At present, it is an important stage for the growth and development of autumn grain in China. however, with the high temperature and little rain in most areas north of the Yangtze River since the beginning of summer, there is a serious drought in many places.

The meteorological monitoring data show that since July, the precipitation in North China, Huang-Huai and the southeast of the northwest region has obviously decreased by more than 50%, among which the precipitation in some parts of central Henan is even more than 80% less, the lowest in the same period in history since 1961.

Why did the north, which entered the main flood season, suffer from a large area of drought at this time? "the lack of precipitation is mainly affected by the strong continental high pressure." Zhang Tao, chief forecaster of the Central Meteorological Observatory, said that at present, most parts of northern China are under the control of the western Pacific subtropical high, resulting in continuous sunny, hot and little rain in the north, especially in North China, Huang-Huai and other places.

Subtropical high, which refers to the warm high pressure system located in the subtropics, is one of the main weather systems that affect the weather in mainland China in summer and cause drought and flood in summer. In the subtropical high pressure area, the weather is generally sunny, when it controls a certain area for a long time, it will often cause high temperature and drought in that area.

"in addition, recently, high temperatures have occurred in most parts of the north, further aggravating soil water evaporation, so the drought has spread rapidly." Zhang Tao said.

It is gratifying that at present, the drought in some of the above-mentioned areas has slightly alleviated. From July 29 to August 1, obvious rainfall has occurred (or will occur) in Shanxi, Hebei, Shandong, Sichuan and other places, according to the Central Meteorological Observatory.

"rainfall is concentrated in North China and the Huang-Huai region, where there is less precipitation in the previous period, which is very beneficial to alleviating the local drought." Mao Liuxi, a researcher at the National Meteorological Center, told reporters that the drought in northwest Anhui has basically alleviated, and the drought in central and eastern Henan has been greatly alleviated.

According to Mao Liuxi, according to the latest monitoring, from the national soil moisture situation, the drought in central and western Henan and Guanzhong, Shaanxi is still continuing or spreading; there are signs of drought in eastern Sichuan Basin, central Hebei, central Inner Mongolia, and Hubei; if there is no precipitation in the later stage, the drought will develop quickly.

Zhang Tao told the Economic Daily that in the next 10 days, except for the strong rainfall along the eastern coast affected by the typhoon, there will be no large-scale strong rain belt across the country, while there will be two small-scale rainfall processes in some parts of North China, but the rainfall is relatively small, and the affected areas are also limited to north-central Hebei, eastern Inner Mongolia and southern parts of Inner Mongolia.

In addition, according to meteorological forecasts, temperatures in most parts of the country in August are close to the same period of the year or on the high side. "at that time, the drought in North China, Huang-Huai and other places may continue or develop, and summer drought is very likely to occur." Mao Liuxi proposed that where conditions permit, artificial rain enhancement or agricultural irrigation should be carried out in a timely manner, meteorological departments should do a good job in weather forecasts, agricultural departments should make detailed monitoring and research, timely grasp the development and changes of drought, and take more measures to increase water sources for drought resistance.

For now, however, there may be no need to worry too much about the autumn grain problem. "this year's drought is not very serious compared with the same period in history." Mao Liuxi said that the distribution of precipitation in China in summer is usually uneven, and drought or waterlogging is more common in some areas as a whole. At present, the main grain producing areas, such as Northeast China and Hunan, have not formed a large area of drought, but grain production in some areas with severe drought has been greatly affected.