Since the beginning of this year, a total of 20 typhoons have formed in the northwest Pacific and South China Sea, and 8 of them have landed on the mainland of my country. The number of typhoons is obviously higher than the number of typhoons, the landing location is northerly, and the path is complex and changeable. At present, due to effective typhoon defense measures, the overall benefits of typhoons that land in my country outweigh the disadvantages. Typhoon rainfall has effectively alleviated the high temperature and drought in the eastern and northern regions.
As of August 19, a total of 20 typhoons have been generated in the northwest Pacific and South China Sea, which is more than 60% higher than the average for the same period of the year (about 12.2). Among them, 8 typhoons have landed in mainland my country, which is more than the average of 3.7 for the same period of the year. More than 1 times more.
According to experts from the meteorological department, this year's typhoons have five main characteristics:
The number of occurrences and landings is obviously too high. This year, the number of typhoons generated and the number of landfalls in mainland my country were respectively 7.8 and 4.3 more than the same period in normal years. Among them, from August 8 to 17, 7 typhoons were generated and 3 landed in mainland my country within 10 days. The eight typhoons currently making landfall are equivalent to the average number of typhoons that land in mainland my country every year (7 to 8).
The landing point of the typhoon is far north, and there are abnormally more typhoons in the Shanghai and Zhejiang areas. Four typhoons have made landfall in Shanghai and Zhejiang this year, which is unusually higher than the number of typhoons that make landfall in the Shanghai and Zhejiang regions in normal years (one). This is the most since 1949.
Typhoon " Yunqiao" made landfall on the coast of jinshan, Shanghai on the morning of August 3. Affected by it, heavy rainfall occurred in many places in East China. The picture shows heavy rainstorms in Haiyan County, Zhejiang Province. China Meteorological Network Picture
The average intensity of typhoons when they land is weak. Among the 8 landfalling typhoons, only 1 was at the strong typhoon level ("Maria") when it made landfall, and the remaining 7 were tropical storms or severe tropical storm levels; the average landfall intensity was 26 meters/second. (Level 10), which is weaker than the multi-year average of 32.8 meters/second (Level 12).
The path of typhoon is complex and changeable. Typhoon No. 4 " Aiwani " circled along the coast of South China and made landfall in South China three times, including two in Guangdong and one in Hainan; Typhoon No. 12 "Yark" moved in an "Ω" path, following landfall After Japan, it landed in my country and circled twice in the southern waters of Japan and the East China Sea; Typhoon No. 16 "Bebiga" made two circles in the coastal waters of western Guangdong, and successively hit Qionghai, Hainan ( Tropical Depression ), Guangdong Yangjiang (tropical depression) and Leizhou (tropical storm) made landfall three times. Affected by the weak airflow that guides the movement of typhoons and the mutual containment of multiple typhoons, the above-mentioned typhoons form complex movement paths that circle or wander offshore, or twist and turn, which greatly increases the difficulty of forecasting and warning.
Typhoon rainfall alleviated the high temperature and drought, but there was a transition from drought to flood in some places. Due to timely forecasts and early warnings and effective defensive measures, the impact of the eight landfalling typhoons outweighed the disadvantages. Some typhoons that penetrate deeply inland bring abundant rainfall, which effectively alleviates high temperatures and drought. The rainfall produced by typhoon "Evanni", the first typhoon to land in my country this year, effectively alleviated the early spring drought in Guangdong and southern Jiangxi; the typhoons "Ambi", "Capricorn" and " Wembia " that penetrated into the inland and moved northward, In addition to "Wembia" causing urban waterlogging and farmland flooding in some areas of Henan and Shandong, the rainfall brought by the typhoon effectively alleviated the high temperature weather in eastern and northern my country and the drought in Huanghuai, Liaoning and Jilin. .
Path map of Typhoon No. 18 "Wumbia" in 2018. Central Meteorological Observatory Figure
Typhoons show the above characteristics and are closely related to the tropical sea temperature in the northwest Pacific, summer monsoon and the intensity of the western Pacific subtropical high (referred to as the subtropical high).
From June to August this year, the tropical ocean surface in the western Pacific remained warm, which was conducive to the development of tropical convection. In addition, the summer monsoon was stronger, resulting in more typhoons this year. At the same time, since mid-July, the dominant typhoon movement path The intensity of the subtropical high is stronger and the position is significantly further north than the same period of normal years. From the end of July to the beginning of August, the ridgeline of the western section of the subtropical high reaches near 40 degrees north latitude, which is 10 latitudes (about 1,000 kilometers) north of the same period of normal years. .Typhoons usually move along the peripheral circulation field on the south side of the subtropical high. The subtropical high is abnormally northward, which causes the source of this year's typhoons to be northward and the moving path to be northward. It is also the main reason why many typhoons move to and land on the coasts of Zhejiang and Shanghai. reason. In addition, the generation of typhoons has been relatively concentrated in the past month, with two "three typhoons co-occurring". The activities of multiple typhoons have dispersed the atmospheric energy on the sea surface, resulting in restrictions on the conditions for each typhoon to intensify. Therefore, so far this year's typhoons have The strength is generally weak.
The China Meteorological Administration Typhoon and Marine Meteorological Forecast Center predicts that in late August, tropical disturbances in the South China Sea or the northwest Pacific will still be active, with 1 to 2 typhoons generated, and will bring wind and rain to the coast of South China; in addition, in Japan Typhoon No. 19 this year "Suli" in the southern ocean will bring strong wind and rain to the East my country Sea, Yellow Sea and Northeast China from the 22nd to the 25th. It is expected that 6 to 7 typhoons may be generated in the northwest Pacific in September, which is more than the same period in normal years (4.9). Among them, 2 to 3 will land in my country, which is more than the same period in normal years (1.8).
