Extreme precipitation in Shanxi

According to the statistics of Shanxi Meteorological Observatory, the precipitation in Shanxi Province mainly occurred from June to September every year in previous years, and the average monthly precipitation in the whole province was only 3 1. 1 mm in June and October, while the process precipitation in Shanxi Province was/from 20: 00 on February 2, 65438 to 8: 00 on October 7 this year. From 20: 00 on October 2, 65438654381to 8: 00 on October 7, 654381,the precipitation in Taiyuan reached 203mm. According to public information, Taiyuan covers an area of 6,909 square kilometers. During this period, Taiyuan received a total of 65.438+0.49 billion cubic meters of rainwater, while the water storage capacity of the West Lake was 65.438+0.4 billion cubic meters, which was equivalent to the water storage capacity of 98.6 West Lakes being pumped into Taiyuan.

According to the public information of Shanxi Energy Bureau, there are currently 682 coal mines in Shanxi Province, with annual production capacity ranging from several hundred thousand tons to 20 million tons. Production coal mines are mainly distributed in 1 1 city, and the annual total production capacity of five cities exceeds1000000 tons: Shuozhou1830000 tons/year; Changzhi 65438+58 million tons/year; Lvliang 65438+26 million tons/year; Jincheng1090,000 tons/year; Jinzhong10.2 million tons/year. Recently, sudden heavy rainfall caused 60 coal mines in Shanxi to stop production. But at the same time, more than 600 coal mines in Shanxi Province are still in normal production, and many coal mines choose to give up their holidays and organize production with all their strength.

Heavy rainfall not only affects coal production, but also has a certain impact on everyone's travel and coal transportation. As of 10, 17, 10, 60 expressway lines in Shanxi were interrupted. Linfen, Yuncheng and Jincheng were the most seriously affected, with 17, 13 and 10 roads interrupted respectively, and local transportation departments were rushing to get through.

Why is there a rare extreme precipitation?

Cause of rainstorm in Shanxi

According to reports, the cause of this rainstorm in Shanxi is related to three factors.

First, the atmospheric circulation situation is stable. The unusually strong western Pacific subtropical high first extended westward and then lifted northward, and then remained stably in Huanghuai area, forming a stable circulation situation in Shanxi with the low-value system of westerly belt, which is conducive to long-term precipitation in Shanxi.

Second, rich water vapor conditions. The southerly airflow on the west side of the subtropical high and the low-level southwest jet continuously transport the water vapor from the South China Sea and the Bay of Bengal from southwest to north to the south-central part of Shanxi, providing a rich source of water vapor for the continuous precipitation in Shanxi.

Third, the low-level conditions last for a long time. Under the stable weather situation, the low-level shear line convergence system was maintained for a long time, and the precipitation echo repeatedly passed through the central part of Shanxi. The complex topography of Luliang Mountain and Taihang Mountain in Shanxi increased the precipitation of the easterly airflow, resulting in heavy precipitation in the central part of Shanxi and northern Linfen.

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It is worth noting that in summer and autumn this year, it is generally rainy in the north, less precipitation in the south, and severe drought in South China. The eastern monsoon region presents the climate anomaly characteristics of "northern waterlogging and southern drought". For example, the rainy season in North China comes early and the autumn rain in West China comes early. There are many precipitation processes in flood season and autumn in the north, and the accumulated rainfall is large. However, due to the continuous influence of subtropical high in the south, the high temperature in the south of the Yangtze River is strong and lasts for a long time. The characteristics of "waterlogging in the north and drought in the south" make the weather and climate performance abnormal this year. The most impressive extreme weather event was the "July 20th" rainstorm in Zhengzhou, with the maximum hourly rainfall of 20 1.9 mm, which broke the historical extreme of Chinese mainland. From the end of September to the beginning of 10, it rained continuously in Shanxi and other places, and the average accumulated precipitation reached more than 100 mm, which was more than three times that of the same period in normal years. At the same time, influenced by the subtropical high, the high temperature in the south of the Yangtze River is strong and lasts for a long time recently, forming a rare autumn high temperature heat wave. Ren Guoyu, chief expert of the National Climate Center and professor of China Geo University (Wuhan), said that compared with the weather and climate in summer and autumn in previous years, this year is indeed very abnormal, and the direct cause of this regional extreme precipitation and high temperature is mainly the abnormal atmospheric circulation in the northern hemisphere and East Asia.

Ren Guoyu said that in recent years, especially this year, the atmospheric circulation in the northern hemisphere is abnormal. In the middle and high latitudes, the upper air circulation becomes more radial and changeable, and the north-south exchange of cold and warm air is more intense and frequent. In addition, the performance of the subtropical high in the western Pacific is very abnormal, which is mainly reflected in the strong intensity, the west-north ridge and the abundant tropical ocean water vapor, which leads to the long stay time of the rain belt from Sichuan Basin to North China and Northeast China, the long duration of precipitation and the accumulated rainfall, while the south is sunny and dry under the control of the subtropical high.

What is the root cause of this extreme weather and climate event, and is it related to global warming? Ren Guoyu said that this is possible, but special research is needed. At present, the climate anomalies in recent years may also be the performance of climate variability on the scale of decades, which is related to the climate transformation in the northern hemisphere in the last 20 years.

As to whether these phenomena mean that we are experiencing a continuous climate change, Hu Xiao, chief meteorologist of Yiyou Weather in China, also said that it is not easy to draw a conclusion at present, only that the weather situation this year is very special and rare, which is a signal to remind us to continue to pay attention to climate change.