How La Niña and climate change can enable our current parade of atmospheric rivers.


La Niña plays a role in allowing our current parade of atmospheric rivers across the Pacific and there could be a link to climate change as well.

Faron Anslow, head of climate analysis and monitoring at the Pacific Climate Impacts Consortium, explains, “The global source of almost all atmospheric rivers here and around the world are the tropics.”

“The water evaporates from the warm ocean there and rises due to the thunderstorm activity and eventually this water vapor moves north and gets carried away in the storm tracks which then bring the water in British Columbia “

“With this next storm coming, it looks like this water has come from close to the Philippines and that has been a feature that has been with us for a good part of the year.

The next atmospheric river will impact the south coast of British Columbia on Tuesday and Wednesday.

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“For reasons we’re not entirely clear on yet, water vapor has been dragged into storms repeatedly for months now.”

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Located off the coast of the Philippines is an area of ​​the Pacific Ocean called the Indo-Pacific Hot Water Pool. A scientific article calls this region the “steam engine” of the world. “

“This is a region of the planet with the warmest ocean temperatures in the world and because of that it is able to withstand what we call really deep convection where there are thunderstorms that go from the surface to the top. to the stratosphere, ”Anslow said.

According to a peer-reviewed scientific article in Science Advances, this Indo-Pacific warm water basin has grown and warmed over the past century due to climate change.

“Research shows that the warmest ocean temperatures in this region are increasing. So basically, as entire regions heat up, the areas that reach that critical threshold for convection get wider and wider to the north and south, ”Anslow said.

“My guess is that the expansion makes it a bit easier for these storms to pick up that moisture and push it across the Pacific Ocean to us.”

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In addition, La Niña, which is happening now, is also increasing the moisture export from the Indo-Pacific warm water basin.

“The La Niña model is for warmer than normal ocean temperatures in this warm pool area,” Anslow said.

“So the Niña in this case enhances that hot pool effect and allows all that moisture to be exported. “

Clearly shown in this upcoming atmospheric river.

“This current storm has a very clear wet trail that stretches from British Columbia all the way to quite close to the Philippines, so all the way across the Pacific Ocean for over 10,000 km.”

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