Five questions from Huaxi Qiuyu!The latest situation of Sichuan -Guizhou and Shaanxi Meteorological Experts | The chief is here

Sichuan: Dare to believe it? The West China Autumn Rain in Sichuan only started half a month later?

Shaanxi: This field can not even pick up the rain!

Guizhou: It seems to be drizzle.

That's right, recently to the "rain" season in the West China region. What is the situation in the autumn rain in various places this year? What are the main impacts? Huaxi Autumn Rain is often "night rain"? The chief of this issue is here. Meteorological experts from the three provinces of Sichuan, Guizhou, and Shaanxi take everyone to know the autumn rain of West China -the "weather coffee" that I have to mention in the autumn!

Source: UNSPLASH

Interview expert:

Tan Wen, an engineer of the Agricultural Meteorological Center of the Institute of Environmental Climate, Guizhou Province

Cai Xinling Zhao Xiaomeng and Li Qian, a forecast at the Shaanxi Provincial Climate Center

President Wang Chunxue, a senior engineer of Sichuan Meteorological Observatory, Wang Chunxue

1. What is Huaxi Autumn Rain?

What is the main cause?

After entering the end of August, in most parts of the country, West China was rainy. In the 1920s and 1930s, Zhu Kezhen and Tu Changwang successively classified the mountainous areas around the Yunnan -Guizhou Plateau and the Sichuan Basin as the West China Climate Zone in the Chinese climate zone. The concept of "West China Autumn Rain" was finally named.

The main administrative areas involved in Huaxi Qiuyu include Hubei, Hunan, Chongqing, Sichuan, Guizhou, Shaanxi, Ningxia, and Gansu.

The formation of the West China Autumn Rain is due to the cold air in the fall south of the autumn to meet the warm and humid air stranded in the area. The warm and cold air confronted for a long time, so it formed a long rainy weather.

The age of autumn rain has changed a lot. Some years of autumn rain are not obvious, and even the air rainy season appears. Taking Sichuan as an example, in October 1962, Ya'an, "Yucheng", was 29 days a month; from September 26 to November 22, 1975, Sichuan had a long -term autumn rain that lasted more than 50 days.

There are many folk names in various places in West China. Shaanxi is called "autumn", Guizhou region is called "falling rain in autumn", and Sichuan region is called "autumn rain".

What is Huaxi Autumn Rain? | Open the "Sky" window series short video

2. How to judge the beginning of West China Autumn Rain?

According to the Meteorological Industry Standard "China Rain Season Monitoring Indicators Huaxi Autumn Rain" (QX/T 496-2019), the first date of the autumn rain in the West of West China and the North and North areas began as the starting date of the entire West China autumn rain.

This year, Huaxi Qiuyu North District (including most southern Shaanxi, southern Ningxia and southern Gansu) entered the autumn rain season on August 25, which was 18 days earlier than the beginning of the perennial rain season in the North District (September 12); as of the end of August, Huaxi Qiuyu South District (including western Hubei, western Hunan, Chongqing, eastern Sichuan, northern Guizhou and south of Shaanxi) have not yet entered the autumn rain season. Therefore, Huaxi Qiuyu was determined in 2022 to start on August 25.

West China Autumn Rain Monitoring Station Space Distribution Map (Red Dot represents North District, and Blue Dot represents South District)

Sichuan:

According to the monitoring of Huaxi Autumn Rain Meteorological Industry Standards (QX/T496-2019), on September 14, the "West China Autumn Rain" in Sichuan Province officially started this year. Sichuan Province usually starts and ended on August 30 and November 1, respectively.

Guizhou:

Guizhou Huaxi Qiuyu has a formal criteria, that is, from September 1st to November 30th each year, a period of rainfall ≥0.1 millimeters and a duration of 5 days or more No rainfall) is defined as the drizzle process in autumn, referred to as autumn rain. This year, the West China Autumn Rain in Guizhou officially started on September 9.

From September 9th to 17th, 22 counties (districts), including 22 counties (districts) of 6 cities including Anshun City, Bijie, Guiyang City, Liupanshui City, Qiannan Prefecture, Qiannan Prefecture, 22 stations in 22 stations in 6 cities. class. Shaanxi:

This year, Huaxi Qiuyu (Shaanxi District) began on August 25, 18 days earlier than usual. From August 25th to 30th, a large -scale continuous precipitation process occurred in central and southern Shaanxi. The West China Autumn Rain Shaanxi Monitoring Area (Guanzhong and Southern Shaanxi) started rainfall from the 25th for 6 consecutive days. , August 25th to 30th is the first rainy season in the fall of this year.

The criteria for judgment of Huaxi Autumn Rain (Shaanxi District) are that starting from August 21, ≥50%of the daily rainfall in the autumn rain monitoring area ≥0.1 mm is a autumn rain day. If there are 5 or more autumn rain days in the area, (There is a non -autumn rain day in the middle), which is a rainy period. The first autumn rain day of the first rainy period is the beginning of the autumn rain.

3. What is the situation of West China autumn rain this year?

The National Climate Center predicts that in the fall of 2022, the strength of the autumn rain in Huaxi is generally stronger than usual, but the space distribution is different.

Compared with the same period of the same year, there are many precipitation in the central and western regions of the southwest and northwest, among which 20 to 50 % are southeast of Gansu, southern Ningxia, central and southern Shaanxi, and northern Sichuan; Among them, 20 to 50 % of the eastern Hubei, Hunan, and eastern Guizhou.

Sichuan:

In 2022, the beginning of the West China Autumn Rain in Sichuan was late compared to the same period (August 30), and it officially started on September 14. It is expected that the intensity of Huaxi autumn rain in Sichuan this year is slightly weaker than the same period of the same year. The end period is close to the same period (November 1), which mainly affects the northwest of the basin, southwest of the basin, and central basin.

Guizhou:

This year, Huaxi Yuyu in Guizhou is mainly concentrated in western Guizhou. Starting from September 9th, September 17th. As of September 19, from the current situation, the signs of "West China Autumn Rain" have not yet appeared in northern Guizhou. Relevant departments still need to strengthen the scientific scheduling of water resources. The timing is carried out manually.

Shaanxi:

It is expected that Huaxi Qiuyu in Shaanxi District is strong this year. The precipitation from August 25th to 30th improved the soil sentiment, effectively alleviating the droughts of most of Guanzhong and southern Shaanxi, and also conducive to the water storage of reservoirs in the upstream of the Weihe River and the Han River.

Huaxi Qiuyu (Shaanxi District) starts September 12 throughout the year, and the end is October 8. After the beginning of the autumn rain, as of October 31, there was no rainy period, and the autumn rain ended, and the end of the last rainy period was the end of the autumn rain at the area of ​​the year.

4. West China Autumn Rain is not large?

Why are you paying attention?

Compared with summer precipitation, the total magnitude of autumn rain is usually not large. Relatively speaking, the chances of thunderstorms, rainstorms, and strong flowing weather are not high, and the intensity of precipitation is maintained in small rain. So why is Huaxi Autumn Rain still received widespread attention?

Sichuan:

Mainly because Huaxi Autumn Rain has a greater impact on agricultural production (including the harvest of Dachun crops and sowing Xiaochun crops). The autumn rain period is exactly in the period of autumn harvest and autumn. Severe autumn rain may cause autumn floods and bring flood disasters.

In 2022, the beginning of the West China Autumn Rain in Sichuan was late, and the autumn rain situation of the year still needed to end in autumn. In late August this year, there was a continuous precipitation weather in Sichuan Province. Although it did not meet the standard of the beginning of the West China Autumn Rain, continuous precipitation still alleviated the early high temperature drought.

It is expected that the strength of Huaxi autumn rain in Sichuan this year is weaker than usual, and there is uneven distribution of water in precipitation. Among them, the average precipitation in the northwest of the basin, southwestern and southwest of the basin is about 10%more than the same period of the same year. The average precipitation of the rest of the autumn rain districts in Sichuan is 10%to 20%less than the same period of the year. In addition, during the autumn rain period, most of the Sichuan Basin will occur in the process of precipitation.

Therefore, this year's West China autumn rain can improve the emotion to a certain extent, which is particularly conducive to alleviating the drought in the northwestern part of the basin, southwest of the basin, and the central part of the basin.

The Western Sichuan Plateau and Pen Zhou Mountains should pay close attention to the weather conditions to prevent geological disasters such as landslides that may cause landslides that may be caused by Huaxi Autumn Rain. Reduce agricultural losses.

Guizhou:

Autumn is the critical period of autumn harvest and autumn. It is beneficial that autumn rain is beneficial to the soil in the arid areas, and it is conducive to the sowing and emergence of winter wheat. The farm proverb has a cloud "you have thousands of grains, I have autumn crickets"; The temperature is low, and mature crops are prone to rot and germination.

At the same time, due to the complex geological structure of the Yunnan -Guizhou Plateau, the floods caused by heavy precipitation and rain and rain can also make the water content of the surface soil reaching saturation, causing secondary disasters such as floods, landslides, and mudslides. At present, during the harvest period of mature crops in autumn, farmers' friends need to pay attention to weather changes and seize the gap between rainfall interruption and grab harvest in time.

Shaanxi:

During the autumn harvest season, long -term rainy and rainy weather not only affects agricultural activities such as autumn harvests and autumn species. Sustainable heavy precipitation may also cause autumn floods, bringing secondary disasters such as waterlogging, landslides, and mudslides, which threatens the safety of the people's lives and property. For example, during the strong autumn of 2003, 2011, and 2021, autumn floods appeared in the upper stream of the Weihe River and the Han River. Especially in 2021, the autumn is significantly stronger, and the precipitation during autumn rain is 3.5 times the same period per year, the most during the same period since 1961. From October 3rd to 6th, 2021, regional heavy rain appeared in the Weihe River Basin, triggering the largest flood in the same period since the measured information in 1935. On October 7th, the largest flood peak since 1979, heavy rainfall and cooling to flood rescue for rescue of flood rescue Increase difficulty.

In October 2021, the flood of the Weihe River passed through the Lintong section of Xi'an, and the Hongfeng of the Weihe River was forming

5. Huaxi Autumn Rain is often "night rain"?

As early as a thousand years ago, the poet Li Shangyin seemed to have completed a weather notes in unintentional.

In the context of the weather in Huaxi Autumn Rain, he wrote a poem: "Jun asked the return period, and the Bashan night rain rose the autumn pool. The climatic characteristics of lingering and more often revealed the considerable night rain rate of Huaxi. According to historical records, Bashan in the poem is probably located in the eastern and western regions of Chongqing.

Source: Science Popularization China

High night rain rate is one of the characteristics of West China autumn rain. Data show that during the autumn rain of Huaxi, the night rainfall in various regions of West China accounted for 60%to 70%of the total rainfall. There are many night rain, mainly affected by the local special terrain.

This is because the air in the southwest region is relatively humid all year round. After the night, the cloud layer has a heat preservation effect on the ground. The upper part of the cloud layer is caused by radiation cooling, which can easily condense water vapor.

Source: Science Popularization China

For agricultural production, night rain has many benefits. Night rain can increase the humidity of the air and soil, and correspond to the rich sunlight during the day of the crops for photosynthesis; the sun and night rain increase the temperature difference between day and night, which is conducive to improving the production and quality of the crop.

In areas where there are many night rain, a large amount of rainwater may penetrate into the soil deep, maintaining sufficient soil moisture, and avoiding the water loss quickly due to high temperature and strong evaporation during the day.

On the other hand, the disaster that occurred late at night brought a lot of inconvenience to disaster relief work. Therefore, it is necessary to strengthen forecasting and forecasting during the night rain during the flood season, and we must not take it lightly for the possible flood conditions.

The China Meteorological Administration's Xuanke Center (China Meteorological News) produced by
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Plan: Zhang Juan

Interviewer: Yang Chunzhu Zhou Wen and Tang Yukun (Wang Meiyu Wu Yue contributed to this article)

Reference materials: China Meteorological News Xinhuanet Science and Popular China, etc.

Edit: Wen Ge

Review: Duan Haoshu

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