The North Atlantic warming hole (NAWH), a region of reduced warming located in the North Atlantic Ocean, significantly affected the North Atlantic jet stream in climate simulations of the future, according to a team of researchers.
Sea surface temperatures (SST) are projected to increase in most of the world's oceans as the result of global climate change. However, in the vicinity of Greenland anomaly exists where the sea-surface temperatures were recorded.
Melissa Gervais, assistant professor of meteorology and atmospheric science, Penn State, who uses the Community Earth Systems Model (CESM) to investigate the impact of the NAWH on atmospheric circulation and midlatitude jets. "We found that this region of the ocean is a very important place for the jet stream that goes across the North Atlantic Ocean."
The researchers published their findings in the Journal of Climate,
Development of the NAWH is linked to a slowdown of the Atlantic Meridional Overturning Circulation, a large system of ocean currents that carries warm water from the tropics northwards into the North Atlantic, and is thought to be due to an influx of fresh water coming from melting Arctic sea ice.
Previous research by Gervais and her team has shown that this increase in fresh water to the ocean changes circulation patterns and leads to surface cooling.
"With more Arctic sea ice melting, more leads into a deep convection," said Gervais who is therefore at Institute for CyberScience co-hire. "That changes the ocean circulation, allowing it to be cool in that south region of Greenland."
This cooling pattern, relative to the global average SST increase, is predicted to become more and more apparent as the 21st century progresses.
"These changes in SST patterns occur as a result of changes in ocean circulation and could have significant impact on circulation and the North Atlantic storm track in the future," said Gervais.
Jet streams, high-altitude currents of wind flowing above the earth, transport air masses and drive weather patterns. The relationship between climate change and jet streams is complex and understanding changes in weather patterns and storm tracks.
In general, we expect to see a poleward shift and eastward elongation of the jet, "said Gervais. "Right now, it's sort of a conflict between the effects of the tropics and impacts of the arctic." So those two things are competing to shift where the jet is located. "
Geralais, Gervais, said that the Pacific jet stream is currently in the process of being pending.
A series of large-ensemble, atmospheric model experiments in the CESM with prescribed SST and sea ice levels over three different time periods.
"We ran three simulations," Gervais said. "One with the current warming-hole conditions; one with the current warming-hole conditions;
Their results indicate that the NAWH plays an important role in the mid-month atmospheric circulation changes in the model's future climate simulation.
"We found that's really quite important for that region," Gervais said. Instead of just thinking about how the tropics and arctic amplification are influencing the jet, we now need to think about how this warming hole is going to influence the jet aircraft in the North Atlantic Ocean are the major contributing factors to the climate change response in the region has received little attention. "
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Melissa Gervais et al., Impacts of the North Atlantic Warming Hole on Future Climate Projections: Mean Atmospheric Circulation and the North Atlantic Jet, Journal of Climate (2019). DOI: 10.1175 / JCLI-D-18-0647.1
North Atlantic warming hole impacts jet stream (2019, April 15)
retrieved 15 April 2019
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