Why is the intensity changing the complicated typhoon "Xuan Lannuo" is so special?

Cover Journalist Teng Yan Survender reporter Feng Rui intern Zhou Xin

According to the Central Meteorological Observatory, as of 8:15 on September 4th, the center of Typhoon No. 11 this year is located in a position of about 470 kilometers east of the south of Zhujiajian Island, Zhejiang Province. The direction moves, and the intensity is gradually strengthened.

Professor Wang Chenghai, a professor and blog director at the School of Atmospheric Sciences of Lanzhou University, said in an interview with the cover journalist that the particularity of "Xuan Lannuo" lies in the formation and development of the formation. It is strong and strong.

Typhoon "Xuan Lannuo" in the next 72 hours path probability forecast map Source: Central Meteorological Observatory

After downgrading or re -developing into a super typhoon level

"This time the typhoon developed faster, and it developed into a super typhoon in about two days." On September 2nd, Zou Chunzheng, director of the Flood Control Division of the Flood Control Department of the Flood and Drought Reactive Department of the Fujian Province, told the cover journalist, "But from today's forecast, Some weakened, the central wind became smaller, weakened from level 17 yesterday to level 14. "

It is understood that the wind level is commonly used in meteorological services to indicate the size of the wind speed. According to the "Tropical Circular Grade" issued by the National Standard Committee, the sign of the 12 -level coastal ships at the 12 -level wind level has been "waves of waves". Generally, the sea surface is 14 meters high. Strong energy.

The decrease in the central wind level means that the typhoon level changes. According to the Central Meteorological Observatory's news on the 2nd, "Xuan Lannuo" weakened from a super typhoon level to a strong typhoon level. The maximum wind speed near the center of the tropical cyclone is divided into six levels. Among them, the super typhoon is the highest level, and its standard is the largest average wind speed near the center center center ≥51.0 meters/s, that is, level 16 or above; followed by strong typhoons, the largest average wind speed near the bottom center is 41.5-50.9 meters per second. , That is level 14-15.

On September 1st, Wang Chenghai said in an interview with the cover reporter that from the current typhoon movement path released by the Central Meteorological Observatory, whether "Xuan Lannuo" can finally land in my country The fierce weather process is also a special atmospheric circulation of tropical ocean. Its generation and movement will definitely interact with the atmospheric circulation of the middle latitude. "

On September 2nd, the reporter learned from the China Meteorological Bureau that the Central Meteorological Observatory expects that "Xuan Lannuo" will move north to west from the 3rd, and move into the East China Sea on the 3rd on the 3rd. Approaching the coast of the northeast of Zhejiang, it is still impossible to rule out the possibility of landing on the eastern coast of my country.

According to the typhoon trend, the impact of "Xuan Lannuo" on my country is also different. Wang Chenghai said that the interaction between "Xuan Lannuo" occurred between the generation and movement and the atmospheric circulation may prompt the subtropical high pressure to weaken, thereby ending the current situation of drought and rain in the Yangtze River Basin. If the typhoon continues to strengthen the north, it will bring a strong wind to the eastern coast. If the circular configuration is reasonable, it will also cause heavy rain. If the subtropical high pressure continues to be strong and stable, and the typhoon enters west in southern my country, it will bring strong wind and precipitation to the southeast coast.

Typhoon "Xuan Lannuo" and the subtropical high -pressure location diagram Source: China Weather Network

Where is the special nature of "Xuan Lan Nuo"?

"'Xuan Lannuo''s particularity is that it is formed in the low -pressure zone on the south side of the subtropical high -pressure south side of the continuous and northern part of the low -pressure zone, and the small tropical low pressure in the low -pressure zone has made" Xuan Lannuo "strong and large. "Wang Chenghai said.

At the same time, the "rapid strengthening" situation shown by "Xuan Lannuo" has a certain relationship with the energy and typhoon its own body. According to CCTV news reports, Dong Lin, chief forecast at the Central Meteorological Observatory, said that due to the large deputy high, the temperature at sea is very high, and the energy of the maritime accumulation some time ago is beneficial to the strength of the typhoon. Secondly, "Xuanlan Nuo" is small and belongs to a micro typhoon, so it is very easy to have a state of rapid enhancement.

According to the "China Meteorological Daily" reported on the 2nd, due to the high pressure of the East Ring subtropical high pressure, and after the deepening of the West wind groove, "Xuan Lannuo" will move north to west and enter the East China Sea warm water area. Essence According to reports, it is very rare for typhoons to reach super typhoon levels in the East China Sea. Global warming and La Nina phenomenon are behind the scenes.

Wang Chenghai also said that some studies have shown that the generation of tropical storms (typhoons) is closely related to global warming. He added that considering many other environmental elements such as the vertical structure of the atmosphere, the relationship between climate change and tropical storms is very complicated, and super typhoons can also be considered a kind of extreme weather.

What is the defense status of the coastal provinces?

The reporter sorted out and found that as of now, there are 27 super typhoons generated in the Pacific and South China Sea in the past five years. Among them, 4 super typhoons have landed in my country. That is one of them.

On August 31, Zhejiang Province's defense finger decided to launch an emergency response to typhoons at sea.

On September 2nd, Zou Chunzhen said in an interview that the current typhoon has a small impact on Fujian's land. It is mainly affected by the sea fishing grounds and past vessels, as well as the coastal breeding industry. "Beginning on August 30, the Flood Control and Drought Resistance Headquarters in Fujian Province required all the fishing vessels in the fishing vessels located in the fishing ground, the eastern part of the Fujian fishing ground and the Diaoyu Islands fishing ground. Relevant sea area operating platforms stop construction and personnel evacuation. As of 21:00 on August 31, a total of 319 related fishing boats were evacuated. On September 1st, the old and weak women and children of the farming and fishing row of Quanzhou, Putian, Fuzhou, and Ningde Pingtan were required to evacuate 1,772 people from the coast of the coast of Hepingtan. The fishing vessels in the western part of the Fujian fishing ground and the waters of the Fujian fishing farm are required to enter Hong Kong before 18:00 on the 2nd, and all people go ashore.

On September 2nd, the National Defense Office and the Emergency Management Department organized a special video of typhoon prevention, emphasizing adherence to the sea, land and windproof, rainproof, and rainproof. Features, personnel should be resolutely transferred, and the facilities should be closed to ensure the safety of the people's lives.

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