분지의 대기오염이 어떻게 폭우를 불러오는가?

How Air Pollution Makes Floods Worse

 

간만에 흥미로운 기사가 떴네요

A better understanding of how aerosols interact with weather could lead to better flood forecasts, fewer floods

 

By Erin Blakemore
smithsonian.com
July 9, 2015

 

 

제목만 보고..

음..미세먼지가 응결핵 역할을 한다는 건가?

이렇게만 생각했는데, 그게 아니네

 

글을 읽다보니 이번 연구가 큰 의의를 갖고 있네요

 

Heavy air pollution has increased rapidly in regions such as China and India, where economic growth and urban populations are booming. Researchers have observed increases in the frequency and intensity of regional floods and droughts over the past few decades. This study establishes a clear connection between severe air pollution and extreme weather events.

 

 

 

 

 

 

On July 9, 2013, heavy floodwaters swept through Beichuan in southwest China's Sichuan province.
Over the course of 5 days, 73 centimeters of rain pounded the mountains, peaking at 29 centimeters in a single day.

 

it’s common knowledge that air pollution can affect health — the World Health Organization estimates that it caused 3.7 million premature deaths worldwide in 2012 alone. But now, reports Science’s Roland Pease, air pollution is being blamed for something else: flooding.

 

Pease writes that an atmospheric science named Jiwen Fan was inspired to study air pollution’s role in flooding after she watched catastrophic floods rush through Sichuan, China in 2013. Fan, who is an air pollution expert, wondered whether air quality played a role in the valley’s disaster, which occurred when nearly 2.5 feet of rain fell in just five days.

 

Together with a team of atmospheric scientists, Fan conducted simulations of how air pollution particles interact with weather. They discovered that in some geographic regions, aerosols absorb heat from the sun, suppressing the chance of rain during the day and stabilizing the atmosphere.  It’s another story at night: the warmed, rising air is transported to mountainous areas before it heads higher up into the atmosphere. This causes massive precipitation that can actually make flooding worse.

 

The team calls their discovery “aerosol-enhanced conditional instability,” and its flipside is that reducing pollution in places like Sichuan can actually reduce floods. There’s another upside to a better understanding of how pollution particles worsen flooding, says the team in a release: it could help future weather forecasters predict floods.

 

“We were amazed at the scale the effect of the pollution had,” Fan told Pease. Perhaps her new research will help prompt people worldwide to commit to reducing air pollution.

 

이와 같은 기사가 여기에,여기(과학적 설명은 여기가 좋고) 또 요기(그림은 여기가 제일 좋음)에도 또 있네요. ^^

 

 

 

 

매커니즘을 좀 알아볼까요?

 

Methods: Led by PNNL, the researchers carried out model simulations of the catastrophic flood event and associated sensitivity simulations. They conducted ensemble simulations at a convection-permitting scale (3 km) using the improved chemistry version of the Weather Research and Forecasting Model (WRF-Chem), a regional-scale model.

 

 

 

1. In the clean air model, moist air at Earth’s surface was heated by the daytime sun, became buoyant, and rose to great heights, triggering a convective cycle that led to storm clouds and mild daytime rainfall.

 

>>>>> 맑은 공기 상태에서의 쓰촨은 위도가 낮아 기온이 높고, 큰 강이 네개나 합류하는, 습도가 높은 분지지형(四川)으로, 위와 같은 현상이 당연했을 것이다. (쓰촨은 여름에 놀러가는 것은 비추입니다. 습하고 찌는 더위에 매운 음식이 발달한 지역이지요)

 

 

 

2. But in the dirty air model, the dark veil over the plain soaked up much of the sun’s warmth high in the atmosphere, while simultaneously cooling the streets and fields below. This altered thermal structure stabilized the daytime atmosphere and suppressed rainfall.

 

>>>>> 오염된 공기가 낮시간 햇빛을 차단하니, 낮시간에 대류를 방해하고 안정층이 형성이 되니 비올 확률이 확연히 낮아지게 됩니다.

 

 

 

3. But as night fell, the moist air mass moved northward toward the Longmen Mountains, which tower some 2000 meters above the basin. The weather system that had been building energy over the plains for 12 hours was driven upward as it collided with the range’s steep contours, triggering the postponed convection. A day’s worth of rainfall from the plains was focused into a few hours over a handful of mountain valleys.

 

>>>>> 평상시 같으면, 1번 문장에 나오는' mild daytime rainfall' 이 나타났을텐데, 

2번 때문에, 에너지를 사용하지 못하고, 그 에너지는 밤이되어 북쪽의 산간지역으로 슬슬 기어오르고, 경사가 급한 산에서 내려오는 차갑고 습한 기류와 만나 (제일 앞에서도 말하지만, regional-scale model로 설명하고 있습니다)  엄청난 폭우를 내린다는 얘기입니다.

 

 

Fan교수가 결론적으로 설명하기를

: Geography and pollution combined to make the floods intensely severe

 

 

 

Illustration of the mechanism the researchers call “aerosol-enhanced conditional instability.” Polluted air containing strong, heat-absorbing particles (bottom panel) suppresses daytime rainfall in the Sichuan Basin, allowing the warm, moisture-laden air to be transported to the mountains downwind. There, it is lifted by topography and dumps heavy rainfall during nighttime. The research finds that reducing local pollution in Sichuan Basin would have substantially alleviated the severity of the 2013 Sichuan flood event.

 

 

 

 

 

 

이것하고 조금 유사한 사례를 들어볼까요?

 

관련 포스트

중국의 밀, 옥수수 농업지대 (중국의 쥐불놀이)

 

 

양자강 근처에서 벌어지는 쥐불놀이 입니다.

이런 쥐불놀이를 하면 아래와 같은 현상이 나타나기도 합니다.

 

 

Darkness at noon: Agricultural smoke blotted out the sun in Nanjing, “burning off” expected thunderstorms.

 

정말로 Darkness at noon이 나타나고 무슨일이 생겼을까?

 

farmers outside the city of Nanjing burned their crop waste en masse, forming a wall of sooty smoke that blotted out the sun in June 2012. Intense thunderstorms had been forecast for the city, but never materialized, though the precipitation downwind the following night was stronger than expected. It is as if anticipated storms can be “burned off by intense air pollution during daytime,”

 

위의 현상하고 비슷하다고 말할 수 있을 겁니다.