China News Service, Beijing, March 1 (Reporter Chen Su) According to data released by the China Meteorological Administration on the 1st, the precipitation in northern China in 2021 will be the second largest in history, second only to 1964, and the annual precipitation in Beijing, Tianjin and Hebei is the largest in history. most.

Talking about the reasons, Xiao Chan, deputy director of the National Climate Center, said that the more precipitation in the north is affected by various factors, which are related to climate warming.

　　At the press conference of the China Meteorological Administration held on the same day, Xiao Chan said that there was a lot of precipitation in the north last year, especially in the Beijing-Tianjin-Hebei region since 1961. the combined influence of factors.

　　Xiao Chan said that, first of all, climate warming aggravates the instability of the climate system and increases the water-holding capacity of the atmosphere. The study believes that an increase in atmospheric temperature of 1°C will increase the water vapor content by 7%. Climate warming will cause frequent occurrence of extreme heavy precipitation events. Global background.

　　"In addition, from August 2020 to March 2021, a moderate-intensity La Niña event occurred in the equatorial central and eastern Pacific. Affected by it, the western Pacific subtropical high began to show an obvious northerly feature from July. Convective activity in the western Pacific continued to be extremely active, which played an important role in the continued northward shift of the subtropical high, resulting in abnormally strong southeast warm and humid air flow from the northwestern Pacific and southwest warm and humid air flow from the Indian Ocean, and provided the northern precipitation as the subtropical high moved northward. Abundant water vapor conditions. At the same time, the Eurasian mid-to-high latitude circulation has a large meridian, cold air activities are frequent, and cold and warm air frequently intersect in northern China, resulting in more precipitation in the northern region.” Xiao Chan said.

　　Xiao Chan said that the increase in precipitation in the north is not only affected by global warming, but also related to interdecadal climate evolution.

In the past 70 years, the main rain belts in China have obvious interdecadal variation characteristics.

From the 1950s to the 1970s, the rainbands were mainly located in the area north of the Yellow River, showing the characteristics of “northern floods and southern droughts”. Since the 1980s, the precipitation showed two rainbands in the north and south, one of which was located in the northeast and northern Inner Mongolia, and the other was located in the northeast and northern Inner Mongolia. The rain belt is located in the middle and lower reaches of the Yangtze River, that is, "southern floods and northern droughts"; in the past ten years, the rain belts have begun to show obvious characteristics of northward uplift and northward expansion, and the precipitation in the Beijing-Tianjin-Hebei region is also mainly on the high side.

　　Looking forward to the precipitation in the northern region in the future, Xiao Chan said that the study shows that the interdecadal variation of precipitation in the north is affected by the North Pacific SST Interdecadal Oscillation (PDO). When the PDO is in the cold water phase, the precipitation in the north is more.

The cycle of PDO is usually 20 to 30 years, and the current cold water phase characteristics will continue for a period of time, which will be beneficial to the overall trend of more precipitation in the north in the future.

(over)