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The North Atlantic warming hole affects the jet stream



  Infection of the North Atlantic warming hole jet stream
Floating iceberg in the Labrador Sea south of Greenland. Credit: Melissa Gervais / Penn State

The North Atlantic warming hole (NAWH), a region of reduced warming located in the North Atlantic Ocean, is significantly affecting the North Atlantic jet stream in the climate simulations of the future, according to a team of researchers.


Ocean surface temperatures (SST) are expected to rise to most of the world's oceans as a result of global climate change. However, within an area of ​​the ocean's spinning waves in the south of Greenland an anomaly exists where the cooler temperatures above the sea are recorded in both global climate-model projects and observations.

"This is called a hole because there is a lack of warming," says Melissa Gervais, assistant professor of meteorology and atmospheric science, Penn State, using the Community Earth System (CESM) model to investigate the effects of NAWH in circulation atmospheric and midlatitude jets. "We have seen that this place of the ocean is an important place for the forcing of the jet stream passing through the North Atlantic Ocean."

Researchers published their findings in the Journal of Climate .

NAWH's development is associated with a slowdown in Atlantic Meridional Overturning Circulation, a large system of ocean currents that bring hot water from the tropics north to the North Atlantic, and is thought to be caused by flowing fresh water that comes from melting the ice in the Arctic sea.

  The impact of North Atlantic's heat affects the jet stream
Floating cave in the Labrador Sea south of Greenland. Credit: Melissa Gervais / Penn State

Gervais and his team's previous research showed that the increase in fresh water in the ocean changes circulation patterns and leads to cooling over.

"More Soluble ice in the Arctic, more water flows into the Labrador Sea, which leads to a reduction in deep convection," says Gervais who is also an Institute for CyberScience co-hire. "The ocean circulation changes, allowing it to cool down to that region in the south of Greenland."

Cooling patterns, related to the global average increase of the SST, are predicted to be larger and more luminous relative to the internal diversity of the ocean as the 21st "These changes to SST patterns are occurring as a result of changes in ocean circulation and may have a significant impact on atmospheric circulation and the North Atlantic storm track in the future, "says Gervais.

Jet streams, high waves of wind that flow over the Earth, transport wind masses and drive weather patterns. The relationship between climate change and the jet stream is complicated and understands the potential impact of climate change on jet streams is important for understanding changes in weather patterns and storms. from Knorr WHOI research vessel. Credit: Melissa Gervais / Penn State
"With climate change we have some ideas about how jets will change. In general, we look forward to seeing a poleward shift and eastward of the jet," says Gervais. "Right now, this is a kind of a tune of war between the effects of the tropics and the effects of the Arctic. So these two things compete with the move where the jet is located."

Most climate models seem to agree that the Pacific jet stream will go to poleward but there are many variations in predictions for the Atlantic, Gervais said.

To investigate how the NAWH's impact on the jet stream progresses, the team is being conducted by a series of large-scale, atmospheric model experiments with CESM prescribed SST and sea ice levels in three different periods of time.

"We run three simulations," Gervais says. "The one with the current condition of the heat-hole, one where the ocean temperature increased to fill the heating hole, and the one where its size was twice deep, to imitate even more clean water from melting ice sheets. "

NAWH plays an important role in the midlatitude changes in the atmosphere at the start of the climate in the future of the model.

"We've found that it's really important for that region," Gervais says. "NAWH is like elongating the jet even more and it changes a bit north. Instead of thinking about how the tropics and arctic influences influence jet influences, we must also consider how this will influence This local change in the North Atlantic jet has a similar magnitude in response to climate change in the region, which indicates that the North Atlantic warming hole can be an important additional factor in pulling war on midlatitude circulation, which has received little attention. "


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More info:
Melissa Gervais et al, Impact of the North Atlantic Warming Hole in the Future Climate Projections: Mean atmospheric Circulation and the North Atlantic jet, Journal of Climate (2019). DOI: 10.1175 / JCLI-D-18-0647.1

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Pennsylvania State University

Citation :
The North Atlantic warming hole affects the jet stream (2019, April 15)
retrieved 15 April 2019
from https://phys.org/news/2019-04-north-atlantic-hole-impacts-jet.html

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