China Weather Network News In October, three typhoons " Lion Mountain ", "Compass" and "Nanchuan" were successively generated. After "Selephony Mountain" landed on the coast of Hainan in my country on the 8th, the compass will land on the coast of Hainan at the afternoon and evening today (October 13), and may become the strongest typhoon to land on Hainan in the past five years. To this end, Central Meteorological Observatory has issued an orange typhoon warning, and China Meteorological Administration has also launched a Level III emergency response. So, why is autumn typhoon so fierce? What are the characteristics of typhoons in this season? China Weather Network has specially counted meteorological big data and analyzed it comprehensively for everyone.
Autumn typhoons are still active, and the number of generations is second only to summer
Usually, we call typhoons generated from June to August "summer typhoons", and typhoons generated from September to November "autumn typhoons". Statistics show that in the past 72 years, 833 typhoons have occurred in summer, which is the most active season for typhoons, and 821 typhoons have occurred in autumn, second only to summer.
Judging from the situation of logging in to my country, the influence of the autumn typhoon should not be underestimated. Data from 1949 to 2020 showed that on average, about 4.43 typhoons landed in my country each year, which is the season with the most typhoons landed in my country; and on average, 2.36 typhoons landed in my country each year, which is the second active season for typhoons; the average number of typhoons landed in spring and winter each year is less than 0.2.
The path is southward. Autumn typhoons prefer the area south of Zhejiang.
Compared with summer typhoons, the landing location of autumn typhoons that land in my country is obviously southward. Meteorological big data shows that summer typhoons mostly land in Guangdong, Fujian, Taiwan, Zhejiang and other places, and typhoon landings are not uncommon in northern regions such as Liaoning, Shandong, and Jiangsu; while autumn typhoons are relatively southerly, and landing points are mostly concentrated in , South China . In the past 72 years, there have been basically no typhoons landing in Jiangsu and its north in autumn.
Take October as an example. The range of typhoons landed in my country is the northernmost to Zhejiang Province and the southernmost to Hainan Province. 95% of the typhoons landed in South China, and the most preferred provinces are Hainan and Guangdong.
According to statistics, between 1949 and 2019, there were 45 typhoons landing in my country in October, of which the most landed in Hainan and Guangdong, both of which were 16. In addition, there are 5 in Fujian, 4 in Taiwan, and 2 in Guangxi and Zhejiang respectively.
Why does typhoon "favor" South China in October? Zhou Ying, a meteorological analyst at China Weather Network, said that this is because the subtropical high pressure retreats south at this time, and typhoons are prone to westward paths, traveling westward along the south side of subtropical high pressure, landing in southern my country.
There are many "harsh characters" in autumn typhoons, and super typhoons account for a high proportion of
Although the number of summer typhoons generated and logged in is the largest in the year, meteorological big data shows that autumn typhoons are more likely to produce "harsh characters". Between 1949 and 2020, among the typhoons generated in autumn, super typhoon accounted for 27.9%, far higher than 18% in summer.
Judging from the intensity of the typhoon's first landing in my country, the autumn typhoon is significantly higher than the summer typhoon. In summer, typhoons mostly land in my country at tropical storms or strong tropical storms, and only 14.9% of them reach strong typhoons or above; in autumn, this proportion reaches 22.4%, significantly higher than in summer.
Judging from the intensity of the typhoons landed in my country in October, from 1949 to 2019, there were 9 tropical storms in , 13 strong tropical storms, 16 typhoons, 6 strong typhoons, and 1 super strong typhoon, accounting for more than 50% of the typhoons and above.
China Weather Network meteorological analyst Shi Yan introduced that starting from the vernal equinox, the direct sunlight point moves from the equator to the Tropic of Cancer, heating the tropical oceans of the northern hemisphere. The sea water heat continues to accumulate. Usually, the sea temperature reaches its highest from August to September. High sea temperatures are conducive to typhoon generation and energy enhancement. At the same time, from the end of August to the beginning of September, cold air began to become active, increasing the pressure gradient, and increasing the wind speed near the center of the typhoon is also conducive to the increase in typhoon intensity. Therefore, in autumn, a higher probability of strong typhoons or super-strong typhoons occur.
From 1949 to 2019, a total of 90 super typhoons were generated in Northwest Pacific and South China Sea in September, and 84 were generated in October, ranking first and second in the year respectively.However, in October, most of the super typhoons are active in the distant seas, and the chances of affecting my country begin to drop significantly.
Autumn typhoon encounters cold air. Disaster impact escalates.
The "ruthless" of autumn typhoon not only reflects the intensity of the typhoon, but also the impact of the disaster may also escalate. As the cold air gradually increases in autumn, typhoons are more likely to encounter cold air, and "Autumn Typhoon + Cold Air" is a terrible combination. The two join forces often trigger violent precipitation, resulting in greater disasters.
For example, Typhoon No. 13, 2010, was generated in October and did not log in to Taiwan directly. It drilled into the South China Sea from Bashi Channel , and then went north to log in to Fujian Zhangpu . The large amount of warm and humid air transported by the typhoon circulation encountered cold air from the north to the south, and the impact of the terrain lifting of the central mountain range in Taiwan, resulting in more than 1,000 mm of precipitation in Suao, Yilan, eastern Taiwan, and the collapse of the Suhua Highway , causing many deaths or disappearances.
The path of autumn typhoons is changeable, and prediction is more difficult
The autumn typhoons are not only outstanding in strength, but also often change in the path. According to the "Typhoons in my country" compiled by the Central Meteorological Observatory in 2015, three typhoons were recorded in the "Typhoons with the most complex path", including Typhoons No. 16 in 1986, Typhoons No. 19 in 1991, and Typhoons No. 16 in 2001, Nari. Among them, "Nate" and "Lily" are both generated in autumn, and the life cycle of "Wayne" is also in late summer and early autumn.
1991 Typhoon "Nat" path map
2001 Typhoon "Nari" path map
2001 Typhoon "Nari" path map
0Autumn typhoon path is more complex and changeable, and is related to the weather system affecting autumn typhoons. Shao Peng, a meteorological analyst at China Weather Network, said that in autumn, such as westerly wind belt , subtropical high pressure, cold air, etc., these weather systems compete with each other without deciding their victory or defeat. It is like a "naughty child" being influenced and controlled by different "parents", so it becomes east and west, south and north, with strange and changeable paths, which greatly increases the difficulty of prediction. Whether in terms of forecast difficulty or power, Typhoon Qiu is a very "ruthless character" and its destructive power cannot be underestimated.
As the typhoon "compass" approaches, there will be strong winds and rains in the southeast coastal areas of my country. The public in relevant areas should be reminded to pay attention to the forecast of the approach and take precautions in advance. (Text/Zhang Hui, Zhang Fangli, Wang Wenwen, Data Support/Shi Yan, Shao Peng, Zhou Ying, Design/Wei Lai, Ren Chengying, Luo Jiaxue)
Source: China Weather Network
