Xinhua News Agency, Beijing, June 22 Question: Why has the recent heavy rainfall continued in the south and the high temperature in the north continued?

　　Xinhua News Agency reporter Huang Yao

　　Recently, heavy rainfall has been "entrenched" in the south, and the high temperature has continued to "barbecue" the north. Is it normal for "southern floods and northern droughts" to occur during this time period?

What is the reason?

　　Experts said that since May, my country's main rain belt has mainly affected southern China and Jiangnan area, and there have been multiple rounds of heavy rainfall. In northern my country, the water vapor conditions have been poor since the beginning of April, and the meteorological drought has continued to develop. In addition, the high-pressure ridge began in mid-June. Development, leading to a significant increase in temperature, together resulting in the recent "southern floods and northern droughts" situation is more prominent.

　　Since June 15, high temperature weather between 35 degrees Celsius and 40 degrees Celsius has occurred in many places in Henan, Hebei, Shandong, Guanzhong, Shaanxi, and northern Jiangsu and Anhui, and the number of high temperature days above 35 degrees Celsius has exceeded 6 days in many places.

Monitoring data show that 842 weather stations exceeded 35 degrees Celsius, of which 520 weather stations exceeded 37 degrees Celsius, and 104 weather stations exceeded 40 degrees Celsius, breaking the historical extreme values ​​for the same period in many places.

At present, the high temperature weather in Huanghuai and other places in North China continues, and the Central Meteorological Observatory continued to issue a high temperature orange warning on the 22nd.

　　Yuan Yuan, the chief on-duty of the National Climate Center during the flood season, said that compared with previous years, the regional high temperature weather this year actually occurred relatively late.

Because the cold air is relatively active in the early stage, the north is relatively cool during the period from May to the early June.

　　She analyzed that there are two main reasons for the continuous high temperature weather: first, the water vapor conditions in the north are poor, the atmosphere is relatively dry, and the relative humidity is low; the second is controlled by a high-pressure ridge, the northwest sinking airflow prevails at high altitude, and the solar radiation is strong, so the high temperature The weather begins to develop and strengthen.

　　"The high temperature in the north will gradually weaken for a period of time in the future. After the subtropical high rises northward, it will mainly control the areas of Jiangnan and central and eastern South China. The high temperature in the south will develop again, and there may be high temperature weather that lasts for a long time." Yuan Yuan said.

　　Contrary to the "burning" in the north, since May, there have been multiple rounds of heavy rainfall in South China, Jiangnan and other places.

　　Data from the National Climate Center shows that since the pre-flood season in South China began on March 24, the precipitation has been less in the early stage and more in the later stage.

The precipitation from May 10 to June 20 was 63% higher than the same period of normal years, the most in the same period in history since 1961.

Since the flood season, the average number of rainy days in the region is 3.9 days, the most since 1961.

As of the 20th, the daily precipitation of 16 national meteorological stations in the four provinces of Fujian, Guangdong, Guangxi and Qiong has exceeded the monthly extreme value. Among them, Shaoguan in Guangdong (286.4 mm, on June 19) and Songxi in Fujian (225.6 mm, on June 18) And Guangxi Longsheng (166.9 mm, June 4) broke the record for the largest daily rainfall since the local station was established.

　　Zhou Bing, chief expert of meteorological services of the China Meteorological Administration, said that the reason for the continuous heavy rainfall in the south is that, on the one hand, under the background of global warming, the instability of the atmospheric circulation system has strengthened, resulting in enhanced convective activities, increased precipitation efficiency, and increased rainfall during precipitation. On the other hand, the ongoing La Niña event provides an important climatic background for the early onset of the South China Sea summer monsoon and the early progress of the rainy season in my country this year. The southwest water vapor transport guided by the monsoon circulation is relatively strong. The continuous transport of water vapor from the Northwest Pacific affects South China and Jiangnan areas in my country; in addition, while the water vapor conditions are abundant, the meridional dimension of the atmospheric circulation in the middle and high latitudes of Eurasia increases, which affects the frequent cold air activities in the eastern part of my country, especially since June. It is active and develops southwardly and strengthens, guiding the cold air southward to affect the southern part of Jiangnan and southern China, which together lead to abnormally high precipitation in the pre-flood season in southern China.

　　The Central Meteorological Observatory predicts that in the next ten days, the main rain belt will rise in a stepwise northward trend, and the continuous heavy rainfall in southern China will end.

Experts remind that with active typhoons in the future, the southern region may encounter heavy rainfall again, and it is necessary to pay attention to preventing disasters such as flash floods, landslides, mudslides and urban and rural waterlogging that may be caused by heavy rainfall.

　　The latest climate forecast bulletin of the National Climate Center shows that in July, the central and southern parts of Northeast China, eastern and southern North China, northern central China, northeastern China, southwestern South China, southern and northeastern Southwest China, southeastern Northwest China, and southwestern Xinjiang , Western Tibet and other places have more precipitation than the same period of the year; except for the southern part of Southwest China, the southwestern part of South China and other places where the temperature is lower than the same period of the year, the temperature in the rest of the country is close to the same period of the year to higher than the same period of the year; 2 to 4 tropical cyclones were generated, which were close to the same period of the year (3.8) to relatively few. Among them, 1 to 2 tropical cyclones landed or affected the coastal areas of my country.