Explainer-What Brought about the Document Rainfall in Beijing and Northern China?

By Ethan Wang and Ryan Woo

BEIJING (Reuters) – Excessive rain battered Beijing, Tianjin and the province of Hebei within the wake of Hurricane Doksuri in late July, inflicting widespread flooding and injury in a area the scale of Britain.

The storms, which have killed not less than 20 folks and led to the displacement of lots of of 1000’s of residents, had been the worst to hit China in over a decade, with Beijing experiencing its heaviest rainfall in 140 years.

HOW SEVERE WAS THE RAINFALL?

The quantity of rainfall since Saturday has breached many native meteorological information.

A reservoir in Beijing’s Changping district logged a precipitation studying of 744.8mm (29.3 inches) between Saturday and Wednesday, essentially the most within the metropolis in over 140 years and much exceeding the earlier report of 609mm set in 1891.

The persistent downpour prompted Beijing to make use of a flood storage reservoir for the primary time since its institution 25 years in the past to divert floodwater.

In Hebei, one native climate station recorded 1,003mm of rain for a three-day interval from Saturday to Monday, an quantity usually seen over half a yr.

HOW DID THE EXTREME RAIN HAPPEN?

Moreover the remnants of Doksuri, heat and humid air-flows and water vapour introduced by Hurricane Khanun slowly transferring within the Western Pacific created the circumstances for the heavy rains, in accordance with Chinese language meteorologists.

Because the residual circulation of Doksuri’s rain clouds headed north, a subtropical and continental excessive strain system within the ambiance additionally blocked their north and eastward passage, resulting in the persevering with convergence of water vapour that acted like a dam storing the water, the meteorologists say.

Topographic options within the space additionally contributed to the climate. As giant quantities of vapour gathered in northern China, it was then lifted up by a low-altitude wind, shifting precipitation east of the Taihang mountain vary, the place the worst-hit areas – together with Beijing’s Fangshan and Mentougou districts – are situated.

In the meantime, a collection of convective clouds gathered over the world, leading to heavy rainfall for a protracted time frame, additional exacerbating the injury and complicating rescue operations.

HOW DAMAGING WAS THE RAIN?

Within the city elements of Beijing, lots of of roads had been flooded, forcing parks and tourism spots to close. A whole lot of flights had been both delayed or cancelled on the metropolis’s two main airports. Some subway strains and trains had been additionally suspended.

The affect was extra pronounced within the metropolis’s western suburbs. In Mentougou and Fangshan districts, raging water coursed down roads, sweeping away vehicles. Villages in mountainous areas had been reduce off, prompting authorities to deploy helicopters to drop off meals, water and emergency provides.

Hebei’s Zhuozhou, a metropolis with greater than 600,000 folks to the southwest of Beijing, was half-submerged, with about 134,000 residents affected and one-sixth of town’s inhabitants evacuated.

HAVE SIMILAR WEATHER EVENTS HAPPENED IN THE PAST?

Rain with depth seen within the newest occasion following weakened typhoons is uncommon in Beijing and its environment. The Chinese language capital has noticed not less than 12 incidences of great rain introduced by typhoons since authorities began preserving information, in accordance with state media.

In 2017 and 2018, Hurricane Haitang and Ampil each dumped over 100mm of rain on Beijing. One of the vital rain occasions was attributable to Hurricane Wanda in 1956, which unleashed greater than 400mm of precipitation within the densely populated metropolis.

(Reporting by Ethan Wang and Ryan Woo; enhancing by Miral Fahmy)

Copyright 2023 Thomson Reuters.