Meteorologists interpret the "train effect" of rainfall in the Pearl River Delta

(Related data drawing)

Under the influence of typhoon "Haikui", heavy rainfall occurred in many parts of Guangdong. The reporter learned from the Guangdong Provincial Emergency Management Department that as of 9:00 on September 8, 10 cities including Guangzhou, Meizhou, Jieyang and Heyuan had been hit by disasters, with more than 160000 people affected and 58000 people transferred from emergency shelters. The heavy rainfall in Guangzhou, Shenzhen, Dongguan, Foshan and other cities caused urban waterlogging. Why did extreme heavy rainfall still occur in the Pearl River Delta after typhoon Haikui was stopped? The reporter interviewed experts from Guangdong Meteorological Observatory.

At around 6:45 on September 5, the 11th typhoon "Haikui" of this year landed in the coastal area of Raoping County, Chaozhou City, Guangdong Province as a tropical storm. This is the third landing of "Haikui" after landing in Taidong City, Taiwan and Dongshan County, Fujian Province. The sea anemone weakened rapidly after landing and stopped numbering at 17:00 on the 6th.

Yang Guojie, chief forecaster of the Guangdong Meteorological Observatory, said that although the sea anemone had stopped compiling, its residual circulation had not completely dissipated and was still hovering in the Pearl River Delta. From July 7 to August 8, the heavy rainfall in Guangzhou, Shenzhen, Dongguan, Foshan and other Pearl River Delta cities also showed a "train effect".

"Train effect" refers to the frequent and continuous generation of small spatial scale heavy rain clouds in a certain place for a period of time, and these heavy rain clouds "queue up" to move in the same direction, forming a "train" arrangement, and continue to "storm" a place, resulting in heavy rainfall. Yang Guojie said that, in addition to the continuous influence of the "sea anemone" residual circulation in the Pearl River Delta, at the same time, the southwest monsoon of the South China Sea and the easterly wind of the northwest Pacific also converge near the "sea anemone" residual circulation, and the abundant moisture brought by multiple streams of air is just constrained in the Pearl River Delta region, and the source constantly triggers strong precipitation cloud clusters, forming a "train effect" conducive to rainfall accumulation, Therefore, two days after the typhoon "Haikui" landed, there was heavy rainfall in the Pearl River Delta.

The Guangdong Meteorological Observatory predicted that there would still be heavy rainfall in the Pearl River Delta and cities and counties in western Guangdong from August 8 to 9. Meteorologists suggest continuing to prevent secondary disasters such as waterlogging, floods in small and medium-sized rivers, mountain torrents, debris flows and landslides caused by heavy rainfall. (Reporter Tian Jianchuan)

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