A Stratospheric Pathway Linking A Colder Siberia To Barents-Kara Sea Ice Loss

[bluewave]

http://advances.sciencemag.org/content/4/7/eaat6025

Previous studies have extensively investigated the impact of Arctic sea ice anomalies on the midlatitude circulation and associated surface climate in winter. However, there is an ongoing scientific debate regarding whether and how sea ice retreat results in the observed cold anomaly over the adjacent continents. We present a robust “cold Siberia” pattern in the winter following sea ice loss over the Barents-Kara seas in late autumn in an advanced atmospheric general circulation model, with a well-resolved stratosphere. Additional targeted experiments reveal that the stratospheric response to sea ice forcing is crucial in the development of cold conditions over Siberia, indicating the dominant role of the stratospheric pathway compared with the direct response within the troposphere. In particular, the downward influence of the stratospheric circulation anomaly significantly intensifies the ridge near the Ural Mountains and the trough over East Asia. The persistently intensified ridge and trough favor more frequent cold air outbreaks and colder winters over Siberia. This finding has important implications for improving seasonal climate prediction of midlatitude cold events. The results also suggest that the model performance in representing the stratosphere-troposphere coupling could be an important source of the discrepancy between recent studies.

https://eos.org/articles/why-are-siberian-temperatures-plummeting-while-the-arctic-warms

By Kimberly M. S. Cartier  26 July 2018

Climate change is warming the Arctic and melting sea ice, yet Siberia has experienced significantly colder and harsher winters for the past few decades. A study published yesterday in Science Advances shows that interactions between melting regional sea ice and the stratosphere—an atmospheric layer spanning about 10–50 kilometers above Earth’s surface—play a key role in creating these frigid winter conditions.

This stratospheric pathway “significantly contributes to the occurrence of the surface cold events over the Eurasian midlatitude, especially in Siberia and East Asia,” Pengfei Zhang, lead scientist on the study, told Eos. Zhang is a postdoctoral researcher in climate science at Purdue University in Lafayette, Ind.

Scientists previously have observed that Siberia experiences colder winters when the Barents and Kara Seas, two sub-Arctic seas off the northern Eurasian coast, exhibit greater sea ice loss in the preceding autumn months. Zhang’s team modeled the cascading effects of that regional sea ice loss to see what factors may lead to a colder Siberia.

They found that modeling the circulation changes in the stratosphere was key in reproducing the observed Siberian chill. “The impact of sea ice loss in late autumn–early winter persists throughout the whole winter due to the long timescale of stratospheric processes,” Zhang explained.

 

The Barents­­ and Kara Seas reach their minimum in sea ice concentration by November each year. Years that have seen the lowest concentrations of sea ice because of warm Arctictemperatures were followed by Siberian cold anomalies lasting through the next 3 months. Average wintertemperatures in the region typically hover around –18°C, but sometimes temperatures drop to –25°C for spans of a week or more. One northern Siberian town even sawtemperatures plummet to –66°C this past January.

 

The explanation for this “warm Arctic, cold Siberia” pattern remained elusive. Scientists debated whether the harsh winter conditions were caused by natural variability in the troposphere—the atmospheric layer closest to the surface—or whether higher atmospheric layers, as some models have suggested, also played a role. Differences between atmospheric circulation models as well as incomplete treatments of the stratosphere within those models complicated the debate, Zhang explained.

In this research, Zhang and his team used an advanced atmospheric general circulation model to link sea ice loss in the Barents and Kara Seas with Siberian surface climate and weather extremes. The models, which include state-of-the-art stratosphere calculations, used observed sea ice concentration to predict sea and air surface temperatures, surface wind velocities, and cold air outbreaks, as well as circulation patterns in the troposphere and stratosphere.

Then they tried to find a distinct trigger. “We switched on and off the stratosphere–troposphere coupling in the model to explicitly isolate the solid pathways underlying the Arctic–Eurasia linkage,” Zhang explained.

 

When the models considered only air circulation near the surface, the researchers found that their simulations yielded a warmer Siberia than what was observed. To get the region as frigid and windy as it has been during recent winters, they found that they needed to include stratospheric circulation as well as mixing between the troposphere and the stratosphere.

In short, they found that decreased sea ice concentrations weaken and shift the stratospheric polar vortex, a low-pressure phenomenon that helps drive regional climate patterns. This weakened polar vortex then causes a colder Siberia.

By accurately accounting for the stratosphere, the team was able to reproduce observed climate conditions in Siberia using only regional sea ice loss rather than ice loss across the entire Arctic.

Can the technique be used to predict, say, the winter climate events over Eurasia? Perhaps, Zhang said, but accuracy depends on whether climate and weather models “can simulate a realistic stratosphere.”

The team is currently exploring whether the stratosphere plays a similar role in linking regional sea ice loss to extreme weather events in the northern reaches of North America.

[Cold Rain]

We need some Katodog up in here.

[frd]

On 7/30/2018 at 7:16 AM, bluewave said:

http://advances.sciencemag.org/content/4/7/eaat6025

Previous studies have extensively investigated the impact of Arctic sea ice anomalies on the midlatitude circulation and associated surface climate in winter. However, there is an ongoing scientific debate regarding whether and how sea ice retreat results in the observed cold anomaly over the adjacent continents. We present a robust “cold Siberia” pattern in the winter following sea ice loss over the Barents-Kara seas in late autumn in an advanced atmospheric general circulation model, with a well-resolved stratosphere. Additional targeted experiments reveal that the stratospheric response to sea ice forcing is crucial in the development of cold conditions over Siberia, indicating the dominant role of the stratospheric pathway compared with the direct response within the troposphere. In particular, the downward influence of the stratospheric circulation anomaly significantly intensifies the ridge near the Ural Mountains and the trough over East Asia. The persistently intensified ridge and trough favor more frequent cold air outbreaks and colder winters over Siberia. This finding has important implications for improving seasonal climate prediction of midlatitude cold events. The results also suggest that the model performance in representing the stratosphere-troposphere coupling could be an important source of the discrepancy between recent studies.

https://eos.org/articles/why-are-siberian-temperatures-plummeting-while-the-arctic-warms

By Kimberly M. S. Cartier  26 July 2018

Climate change is warming the Arctic and melting sea ice, yet Siberia has experienced significantly colder and harsher winters for the past few decades. A study published yesterday in Science Advances shows that interactions between melting regional sea ice and the stratosphere—an atmospheric layer spanning about 10–50 kilometers above Earth’s surface—play a key role in creating these frigid winter conditions.

This stratospheric pathway “significantly contributes to the occurrence of the surface cold events over the Eurasian midlatitude, especially in Siberia and East Asia,” Pengfei Zhang, lead scientist on the study, told Eos. Zhang is a postdoctoral researcher in climate science at Purdue University in Lafayette, Ind.

Scientists previously have observed that Siberia experiences colder winters when the Barents and Kara Seas, two sub-Arctic seas off the northern Eurasian coast, exhibit greater sea ice loss in the preceding autumn months. Zhang’s team modeled the cascading effects of that regional sea ice loss to see what factors may lead to a colder Siberia.

They found that modeling the circulation changes in the stratosphere was key in reproducing the observed Siberian chill. “The impact of sea ice loss in late autumn–early winter persists throughout the whole winter due to the long timescale of stratospheric processes,” Zhang explained.

 

The Barents­­ and Kara Seas reach their minimum in sea ice concentration by November each year. Years that have seen the lowest concentrations of sea ice because of warm Arctictemperatures were followed by Siberian cold anomalies lasting through the next 3 months. Average wintertemperatures in the region typically hover around –18°C, but sometimes temperatures drop to –25°C for spans of a week or more. One northern Siberian town even sawtemperatures plummet to –66°C this past January.

 

The explanation for this “warm Arctic, cold Siberia” pattern remained elusive. Scientists debated whether the harsh winter conditions were caused by natural variability in the troposphere—the atmospheric layer closest to the surface—or whether higher atmospheric layers, as some models have suggested, also played a role. Differences between atmospheric circulation models as well as incomplete treatments of the stratosphere within those models complicated the debate, Zhang explained.

In this research, Zhang and his team used an advanced atmospheric general circulation model to link sea ice loss in the Barents and Kara Seas with Siberian surface climate and weather extremes. The models, which include state-of-the-art stratosphere calculations, used observed sea ice concentration to predict sea and air surface temperatures, surface wind velocities, and cold air outbreaks, as well as circulation patterns in the troposphere and stratosphere.

Then they tried to find a distinct trigger. “We switched on and off the stratosphere–troposphere coupling in the model to explicitly isolate the solid pathways underlying the Arctic–Eurasia linkage,” Zhang explained.

 

When the models considered only air circulation near the surface, the researchers found that their simulations yielded a warmer Siberia than what was observed. To get the region as frigid and windy as it has been during recent winters, they found that they needed to include stratospheric circulation as well as mixing between the troposphere and the stratosphere.

In short, they found that decreased sea ice concentrations weaken and shift the stratospheric polar vortex, a low-pressure phenomenon that helps drive regional climate patterns. This weakened polar vortex then causes a colder Siberia.

By accurately accounting for the stratosphere, the team was able to reproduce observed climate conditions in Siberia using only regional sea ice loss rather than ice loss across the entire Arctic.

Can the technique be used to predict, say, the winter climate events over Eurasia? Perhaps, Zhang said, but accuracy depends on whether climate and weather models “can simulate a realistic stratosphere.”

The team is currently exploring whether the stratosphere plays a similar role in linking regional sea ice loss to extreme weather events in the northern reaches of North America.

 

@bluewave

This was a very interesting read , do you feel there will be a winter correlation here ( East Coast ) as in high scale winter events on the East Coast ?  

And do you think blocking episodes in the AO domain will be greater this winter becasue of the things mentioned iin the article . Thanks 

I already see some indications the the PV is elongating and might be prone to influences from the Pac and the Atlantic , thoughts ?

 

 

[LibertyBell]

On 10/11/2018 at 11:12 AM, frd said:

 

@bluewave

This was a very interesting read , do you feel there will be a winter correlation here ( East Coast ) as in high scale winter events on the East Coast ?  

And do you think blocking episodes in the AO domain will be greater this winter becasue of the things mentioned iin the article . Thanks 

I already see some indications the the PV is elongating and might be prone to influences from the Pac and the Atlantic , thoughts ?

 

 

Had to correct the last part, Oymjakon reached -88 not -66, and it was -98 back in 2013!  No location in the Northern Hemisphere has yet reached -100

 

from the article

 

\

In this remote outpost in Siberia, the cold is no small affair.

Eyelashes freeze, frostbite is a constant danger and cars are usually kept running even when not being used, lest their batteries die in temperatures that average minus-58 degrees Fahrenheit in the winter, according to news reports.

This is Oymyakon, a settlement of some 500 people in Russia’s Yakutia region, that has earned the reputation as the coldest permanently occupied human settlement in the world.

It is not a reputation that has been won easily. Earlier this week, a cold snap sent temperatures plunging toward record lows, with reports as extreme as minus-88 degrees Fahrenheit. The village recorded an all-time low of minus-98 degrees in 2013.