(China Focus Face to Face) What is the connection between the heavy rains in Henan and global climate change? ——Interview with Jia Xiaolong, Deputy Director of the National Climate Center
China News Service, Beijing, July 23. Title: What is the connection between Henan's heavy rain and global climate change?
——Interview with Jia Xiaolong, Deputy Director of the National Climate Center
China News Agency reporter Chen Su
On July 20th, Henan, China encountered extreme heavy rainfall, which was rare in history. Zhengzhou and other places experienced a year of rain in three days. At the same time, Western Europe also encountered extreme heavy rains. Floods caused by heavy rains caused hundreds of people. die.
At present, extreme weather events are occurring more and more frequently, and major natural disasters are being reported in the media more and more frequently.
What was the cause of the heavy rain in Henan?
What is the connection with global climate change?
At present, China is in a critical period of "seven lower and eight upper" flood control. What is the situation of flood control in the later stage?
Jia Xiaolong, deputy director of the National Climate Center, accepted an exclusive interview with a reporter from China News Agency for an authoritative interpretation.
Jia Xiaolong.
Photo courtesy of me
Excerpts from the interview are as follows:
China News Agency reporter: Recently, Henan suffered extremely heavy rainfall, which caused severe floods and caused social concern. How extreme is this round of Henan rainstorm compared with the same period in history?
Jia Xiaolong:
Since the 17th, record-breaking extreme heavy precipitation events have occurred in many parts of Henan, which have the characteristics of large cumulative rainfall, wide range of heavy precipitation, strong precipitation extremes, concentrated short-term heavy precipitation periods and long duration.
The accumulated rainfall is large.
From July 17 to 22, the precipitation in central and northern Henan was generally 200-400 mm. The cumulative precipitation in 39 counties and cities in Henan reached more than half of the local annual precipitation. Among them, Zhengzhou, Huixian and Qixian Wait for 10 counties and cities to exceed the local annual precipitation.
The range of heavy rainfall is wide.
The heavy rainfall with cumulative rainfall exceeding 250 mm covers an area of approximately 52,000 square kilometers, accounting for 31.1% of the total land area of Henan, which exceeds the historical "75·8" rainstorm process (34,500 square kilometers) in Henan’s history, and 65% of the province’s national weather Heavy rains have occurred at the stations, and 44% of the stations have experienced heavy rains.
Rainfall is extremely extreme.
Since the 17th (as of 08:00 on the 22nd), the daily precipitation of 19 counties and cities in Henan has exceeded the historical extreme value, far exceeding "75·8" (5), and the precipitation of 32 counties and cities has exceeded the historical extreme for 3 consecutive days , The number far exceeds "75·8" (15).
The periods of short-term heavy precipitation are concentrated and the duration is long.
Beginning on the night of the 18th, heavy rains, heavy rains, and local heavy rains began in northern, central, and western areas of Henan. On the 19th to 20th, two consecutive days of heavy rain concentrated in Zhengzhou and its surrounding areas.
The rainfall in Zhengzhou reached 201.9 millimeters at 16:00 on the 20th, breaking the historical extreme value of hourly rainfall in mainland China (198.5 millimeters, Henan Linzhuang, August 5, 1975).
On July 20, a heavy rain in Zhengzhou, Henan caused a disaster.
The picture shows the citizens supporting each other across the road with stagnant water.
Photo by China News Agency reporter Li Chaoqing
China News Agency reporter: Why is there extremely heavy rainfall in Henan? Is it related to global climate change?
Jia Xiaolong: The
recent extreme heavy precipitation event in Henan Province occurred under the background of global warming. The northern precipitation concentration period of "seven lower and eight upper" is the direct result of the abnormal synergistic effect of the atmospheric circulation in East Asia.
1. Global warming has aggravated the instability of the climate system, which is the fundamental reason for the frequent and increased intensity of extreme weather and climate events.
In the context of global warming, extreme weather and climate events are becoming more and more intense. A large number of studies have confirmed that as the climate warms, the atmosphere can hold more water vapor before it is saturated, and the possibility of extreme heavy precipitation increases.
The recent severe floods in Western Europe and the "July 20" torrential rain in Henan, China are both concrete manifestations of the frequent occurrence of extreme heavy rainfall events.
2. Taihang Mountain and Funiu Mountain are the topographical factors that caused this extreme heavy rainfall.
The special topography of Taihang Mountain and Funiu Mountain has an uplifting and convergence effect on the easterly airflow. The heavy precipitation area is stable and less moving in the western and northwestern mountainous areas of Henan Province, and the precipitation in front of the windward slope of the terrain has increased significantly.
3. The period of "seven down and eight up" is the period of concentrated precipitation in northern China. Many extreme rainstorms in history have occurred during this period, such as the "7·8" torrential rain in Henan and the "7.21" torrential rain in 2012 in Beijing.
According to statistics, the precipitation in Henan in July is the maximum in each month of the year, and the precipitation in July-August accounts for about 42% of the annual precipitation, which is a time when heavy precipitation is prone to occur throughout the year.
4. The abnormal synergy of East Asian atmospheric circulation is the direct cause of this extremely heavy precipitation.
Recently, the western Pacific subtropical high has been stronger and northerly, extending westward to the eastern part of North China and the eastern part of Huanghuai area. Henan is at the western edge of the subtropical high and has sufficient convective and unstable energy.
At the same time, typhoon activities in the tropics have entered a period of frequent occurrence, which has strengthened the transportation of water vapor from the Northwest Pacific, the South China Sea and the Bay of Bengal, providing a sufficient source of water vapor for heavy rainfall in Henan.
At the same time, the strong subtropical high pressure in the western Pacific and the continental high pressure in Central Asia stabilized the atmospheric circulation and further extended the duration of heavy rainfall in Henan and other places.
On July 21, Henan, Zhengzhou, the second day of heavy rain, there were many vehicles trapped in the water area.
Image source: ICphoto
Reporter from China News Service: Since the beginning of this year, the northeast and north China have generally had more rainfall. The Northeast has experienced more serious floods in the early period. Why is there more rainfall in the north this year? Is it related to climate change?
Jia Xiaolong:
Since the main flood season this year (June 1st to July 22nd), the Northeast region (eastern Inner Mongolia, Heilongjiang, Jilin, Liaoning) has 15% more precipitation than the same period in normal years (the 15th in history since 1951); Huanghuai (Hebei, Beijing, Tianjin, Shanxi, Shandong, Henan) is 58.5% higher (the fourth in history since 1951).
The main reason for the more rainfall since the flood season in the north this year is that the northeast cold vortex was active from June to early July, and the northwestern Pacific subtropical high was phased to the north, which is conducive to the convergence of cold and warm air in the northern region; after the start of the rainy season in North China in mid-July At the same time, the northwest Pacific subtropical high ridge line moved northward, and the southwest vortex was active, moving in the direction of North China and Huanghuai. Accompanied by active typhoons in the Northwest Pacific and South China Sea, the water vapor in Huanghuai and North China was sufficient, leading to more precipitation in the northern region.
In addition, the early flood season and more rainfall in the north this year have a greater relationship with the abnormalities such as sea temperature and snow cover. A mid-strength La Niña event occurred in the autumn, winter and spring of 2020/2021, and the spring and summer sea temperature distribution in the North Atlantic showed a three-pole distribution. With the characteristics of positive phase, the Qinghai-Tibet Plateau has significantly less snow in winter and spring. These anomalies in ocean and land conditions are conducive to the northwestern Pacific subtropical high, the strong East Asian summer monsoon and the active northeast cold vortex in early summer, which in turn is conducive to the rainy north.
This year, whether in China or other parts of the world, extreme weather and climate events are frequent and strong, which are closely related to global warming.
On July 21, heavy rain caused serious water accumulation in Zhengzhou City.
Photo by Wang Zhongju published by China News Service.
Image source: CNSPHOTO
Reporter from China News Service: At present, China has entered a critical period of "seven lower and eight upper" flood control. How does China's rainfall during this year's flood season compare with previous years? Last year, China suffered the worst flood disaster since 1998. How does China's flood control situation compare with last year?
Jia Xiaolong:
Since the main flood season this year, the areas with heavy rainfall in China are mainly in the north.
Since June (June 1-July 22), the national average precipitation is 177.7 mm, 4.1% less than the same period in normal years.
The spatial distribution of precipitation varies greatly. The areas with more precipitation are mainly in the north of the Yangtze River. The northwestern part of Northeast China, the central-eastern part of North China, the western part of Huanghuai, the northeastern part of Sichuan, the southeastern part of Liaoning, and the northeastern part of Inner Mongolia are more than 50% to 20%. In the north-central part of Northwest China, most of southern China, southern Jiangnan, and central and southern Yunnan, it is 20% to 80% less.
Compared with last year, last year's flood disasters mainly occurred in the Yangtze River and Huaihe River Basins, with heavy rains in many processes and long durations, and the affected areas were large.
Since the flood season this year, extreme precipitation has been relatively high, and the flood situation has been characterized by phases, mainly in the northern regions.
For example, in mid-June, there was a lot of rainfall in Northeast China, and heavy flooding occurred in the Heilongjiang River Basin; from late June to early July, the rainfall during the Meiyu period in the south of the Yangtze River was relatively strong; on July 12, the rainy season in North China began, and most of North China appeared on 12-14 The strongest precipitation process since the flood season, 15-17, the southern Huanghuai and northern Jianghuai experienced heavy precipitation, 19-22, Henan and southern Hebei experienced heavy precipitation, the Yellow River tributaries and Haihe tributaries appeared floods, and urban waterlogging was serious. and many more.
At present, it is the critical period of "seven lower and eight upper" flood control. The flood control situation is still not optimistic. It is expected that there will be more precipitation in the western Northeast, northern Northwest China, northern North China, Jianghuai, Jiangnan, South China and other places during the late flood period, and the Songnen River Basin and the Yellow River. The upper and middle reaches, the Haihe River, the Huaihe River, the lower Yangtze River, and the Pearl River Basin are more likely to have staged floods.
On July 21, heavy rain caused serious water accumulation in Zhengzhou City.
Photo by Wang Zhongju, published by China News Agency. Image source: CNSPHOTO
China News Agency reporter: What is the current flood control situation in the South? How does the rainfall compare to the same period in history?
Jia Xiaolong:
Since June (June 1 to July 22), the average precipitation in the southern region has been 294.1 mm, 12.0% less than the same period in normal years, and the lowest since 2010.
The precipitation in the Yangtze River Basin was 293.0 mm, 9% less than normal in the same period, and the second lowest since 2010, after 2018 (290.5 mm).
The precipitation in the Pearl River Basin was 322.2 millimeters, 26.3% less than normal in the same period, which was the lowest in history since 1990.
In the latter part of the flood season, there will be periods of heavy precipitation in the Jianghuai, Jiangnan, and South China. The southeast coast will also be affected by wind and rain caused by typhoon activities. It is necessary to pay attention to the impact of heavy precipitation on the lower reaches of the Yangtze River, parts of the Pearl River, and other small and medium rivers, lakes, and urban waterlogging.
On July 22, affected by the typhoon "Chapaka", Nanning City, Guangxi ushered in heavy rain, and citizens traveled in the rain.
Photo by Edison Chen
China News Service: The main flood season in China will continue for some time. What is the weather situation in the later period? Will there be more rainfall in the north? What key weather needs to be paid attention to?
Jia Xiaolong: It
is expected that in the latter part of the flood season, China's precipitation will still show phased changes.
In late July, the east of Jiangnan and the east of Jianghuai were mainly affected by typhoon landing, and the precipitation was obviously higher.
There are mainly two rainy belts in the north and south in August. The rainy areas in the north are mainly located in the northwestern part of the northwest, the northern part of the north, the southwestern part of the northeast, the central and western parts of Inner Mongolia, and the southern rainy areas are mainly located in most of southern China and the central and eastern parts of the south of the Yangtze River.
From early to mid-August, the southwestern part of Northeast China, the eastern part of Northwest China, Jiangnan, South China and other places have more precipitation. It is necessary to prevent floods, geological disasters and urban and rural waterlogging that may be caused by heavy precipitation and strong local convective weather.
August is the active typhoon season, and the coastal areas of South China and East China need to guard against the disasters of heavy rainfall, strong winds and storm surges caused by typhoons.
Jia Xiaolong.
Photo courtesy of me
China News Agency reporter: What should we do in the face of severe floods? From the perspective of weather protection, how should the flood season be safe?
Jia Xiaolong:
China is in the "seven lower and eight upper" flood seasons. According to weather forecasts, there are still heavy rainfall in some places recently.
It is necessary to fully understand the current situation facing the critical period of flood prevention, provide weather services for flood prevention and disaster relief, improve the level of early warning and forecast of rainfall, typhoons, mountain torrents, and mudslides, and earnestly play the role of the first line of defense for meteorological disaster prevention and mitigation.
In the face of flood conditions, we must always put the protection of people’s lives and property safety in the first place, and consolidate the main responsibilities. Leading cadres must take the lead to go deep into the front line, take forward command, organize flood control and emergency rescue and disaster relief; strengthen weather monitoring, forecasting and early warning, and improve and improve. Work mechanism, do a good job in extreme weather dynamic monitoring, comprehensively and carefully investigate all kinds of hidden dangers; to improve the work plan, it is necessary to strengthen the coordination of departments and river basins to improve the level of scientific decision-making.
From the perspective of meteorological protection, not only weather forecasts, but also mid-term forecasts and climate forecasts need to be done, and forecast information should be released as early as possible, in a timely and accurate manner, so as to assist relevant departments in making disaster prevention and mitigation arrangements in advance to ensure a safe flood season.
(Finish)