Pacific circulation response to eastern Arctic sea ice reduction in seasonal forecast simulations

AbstractRecent studies point to the sensitivity of mid-latitude winter climate to Arctic sea ice variability. However, there remain contradictory results in terms of character and timing of Northern Hemisphere large-scale circulation features to Arctic sea ice changes. This study assesses the impact of realistic late autumn eastern Arctic sea ice anomalies on atmospheric wintertime circulation at mid-latitudes, pointing to a hidden potential for seasonal predictability. Using a dynamical seasonal prediction system, an ensemble of seasonal forecast simulations of 23 historical winter seasons is run with reduced November sea ice cover in the Barents-Kara Seas, and is compared to the respective control seasonal hindcast simulations set. A non energy-conserving approach is adopted for achieving the desired sea ice loss, with artificial heat being added conditionally to the ocean surface heat fluxes so as to inhibit the formation of sea ice during November. Our results point to a robust atmospheric circulation response in the North Pacific sector, similar to previous findings on the multidecadal timescale. Specifically, an anticyclonic anomaly at upper and lower levels is identified over the eastern midlatitude North Pacific, leading to dry conditions over the North American southwest coast. The responses are related to a re-organization (weakening) of west-Pacific tropical convection and interactions with the tropical Hadley circulation. A possible interaction of the poleward-shifted Pacific eddy-driven jet stream and the Hadley cell is discussed. The winter circulation response in the Euro-Atlantic sector is ephemeral in character and statistically significant in January only, corroborating previous findings of an intermittent and non-stationary Arctic sea ice-NAO link during boreal winter. These results aid our understanding of the seasonal impacts of reduced eastern Arctic sea ice on the midlatitude atmospheric circulation with implications for seasonal predictability in wintertime.

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Two leading modes of wintertime atmospheric circulation drive the recent warm Arctic-cold Eurasia temperature pattern

10.5194/egusphere-egu2020-9705 ◽

2020 ◽

Author(s):

kunhui Ye ◽

Gabriele Messori

Keyword(s):

Sea Ice ◽

Atmospheric Circulation ◽

North Atlantic ◽

Arctic Sea Ice ◽

The Arctic ◽

The North ◽

Downward Longwave Radiation ◽

North Asia ◽

Arctic Sea ◽

The North Atlantic

<p>The wintertime warm Arctic-cold Eurasia (WACE) temperature trend during 1990-2010 was characterized by accelerating warming in the Arctic region, cooling in Eurasia and accelerating autumn/winter Arctic sea ice loss. We identify two atmospheric circulation modes over the North Atlantic-Northern Eurasian sector which displayed strong upward trends over the same period and can explain a large part of the observed decadal WACE pattern. Both modes bear a close resemblance to well-known teleconnection patterns and are relatively independent from anomalies in Arctic sea-ice cover. The first mode (PC1) captures the recent negative trends in the North Atlantic Oscillation and increased Greenland blocking frequency while the second mode (PC2) is reminiscent of a Rossby wave train and reflects an increased blocking frequency over the Urals and North Asia. We find that the loss in the Arctic sea ice and the upward trends in the PC1/PC2 together account for most of the decadal Arctic warming trend (>80%). However, the decadal Eurasian cooling trends may be primarily ascribed to the two circulation modes alone: all of the cooling in Siberia is contributed to by the PC1, and 65% of the cooling in East Asia by their combination (the contribution by PC2 doubles that by PC1). Enhanced intraseasonal activity of the two circulation modes increases blocking frequencies over Greenland, the Ural region and North Asia, which drive anomalous moisture/heat flux towards the Arctic and alter the downward longwave radiation. It weakens warm advection and enhances advection of Arctic cold airmass towards Eurasia.</p>

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Two Leading Modes of Wintertime Atmospheric Circulation Drive the Recent Warm Arctic–Cold Eurasia Temperature Pattern

Journal of Climate ◽

10.1175/jcli-d-19-0403.1 ◽

2020 ◽

Vol 33 (13) ◽

pp. 5565-5587 ◽

Cited By ~ 1

Author(s):

Kunhui Ye ◽

Gabriele Messori

Keyword(s):

Sea Ice ◽

Atmospheric Circulation ◽

North Atlantic ◽

Arctic Sea Ice ◽

The Arctic ◽

The North ◽

Downward Longwave Radiation ◽

North Asia ◽

Arctic Sea ◽

The North Atlantic

AbstractThe wintertime warm Arctic–cold Eurasia (WACE) temperature trend during 1990–2010 was characterized by accelerating warming in the Arctic region, cooling in Eurasia, and accelerating autumn/winter Arctic sea ice loss. We identify two atmospheric circulation modes over the North Atlantic–northern Eurasian sector that displayed strong upward trends over the same period and can explain a large part of the observed decadal WACE pattern. Both modes bear a close resemblance to well-known teleconnection patterns and are relatively independent from variability in Arctic sea ice cover. The first mode (PC1) captures the recent negative trends in the North Atlantic Oscillation and increased Greenland blocking frequency, while the second mode (PC2) is reminiscent of a Rossby wave train and reflects an increased blocking frequency over the Urals and north Asia. We find that the loss in the Arctic sea ice and the upward trends in PC1 and PC2 together account for most of the decadal Arctic warming trend (>80%). However, the decadal Eurasian cooling trends may be primarily ascribed to the two circulation modes alone: all of the cooling in Siberia is contributed to by PC1 and 65% of the cooling in East Asia by their combination (the contribution by PC2 doubles that by PC1). Enhanced intraseasonal activity of the two circulation modes increases blocking frequencies over Greenland, the Ural region, and north Asia, which drive anomalous moisture/heat flux toward the Arctic and alter the downward longwave radiation. This also weakens warm advection and enhances advection of cold Arctic airmasses towards Eurasia.

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Ocean–Atmosphere State Dependence of the Atmospheric Response to Arctic Sea Ice Loss

Journal of Climate ◽

10.1175/jcli-d-16-0531.1 ◽

2017 ◽

Vol 30 (5) ◽

pp. 1537-1552 ◽

Cited By ~ 22

Author(s):

Joe M. Osborne ◽

James A. Screen ◽

Mat Collins

Keyword(s):

Sea Ice ◽

North Pacific ◽

Arctic Sea Ice ◽

The Arctic ◽

The North ◽

Arctic Sea ◽

Ocean Atmosphere ◽

Arctic Sea Ice Loss ◽

The North Pacific ◽

Sst Anomalies

Abstract The Arctic is warming faster than the global average. This disproportionate warming—known as Arctic amplification—has caused significant local changes to the Arctic system and more uncertain remote changes across the Northern Hemisphere midlatitudes. Here, an atmospheric general circulation model (AGCM) is used to test the sensitivity of the atmospheric and surface response to Arctic sea ice loss to the phase of the Atlantic multidecadal oscillation (AMO), which varies on (multi-) decadal time scales. Four experiments are performed, combining low and high sea ice states with global sea surface temperature (SST) anomalies associated with opposite phases of the AMO. A trough–ridge–trough response to wintertime sea ice loss is seen in the Pacific–North American sector in the negative phase of the AMO. The authors propose that this is a consequence of an increased meridional temperature gradient in response to sea ice loss, just south of the climatological maximum, in the midlatitudes of the central North Pacific. This causes a southward shift in the North Pacific storm track, which strengthens the Aleutian low with circulation anomalies propagating into North America. While the climate response to sea ice loss is sensitive to AMO-related SST anomalies in the North Pacific, there is little sensitivity to larger-magnitude SST anomalies in the North Atlantic. With background ocean–atmosphere states persisting for a number of years, there is the potential to improve predictions of the impacts of Arctic sea ice loss on decadal time scales.

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Contributions from intrinsic low-frequency climate variability to the accelerated decline in Arctic sea ice in recent decades

10.5194/acp-2018-127 ◽

2018 ◽

Author(s):

Lejiang Yu ◽

Shiyuan Zhong

Keyword(s):

Sea Ice ◽

Atmospheric Circulation ◽

Large Scale ◽

Low Frequency ◽

Arctic Sea Ice ◽

The Arctic ◽

Self Organizing Maps ◽

The North ◽

Arctic Sea ◽

Atmospheric Circulation Anomalies

Abstract. In recent decades, the Arctic sea ice has been declining at a rapid pace as the Arctic is warmed at a rate of twice the global average. The underlying physical mechanisms for the Arctic warming and accelerated sea ice retreat are not fully understood. In this study, we apply a relatively novel statistical method called Self-Organizing Maps (SOM) to examine the trend and variability of autumn Arctic sea ice in the past four decades and their relationships to large-scale atmospheric circulation changes. Our results show a large portion of the autumn Arctic sea ice decline between 1979 and 2016 may be associated with anomalous autumn Arctic intrinsic atmospheric modes. The Arctic atmospheric circulation anomalies associated with anomalous sea surface temperature patterns over the North Pacific and North Atlantic influence Arctic sea ice primarily through anomalous temperature and water vapor advection and associated radiative feedback.

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The contributions of the leading modes of the North Pacific sea surface temperature variability to the Arctic sea ice depletion in recent decades

10.5194/tc-2019-38 ◽

2019 ◽

Cited By ~ 1

Author(s):

Lejiang Yu ◽

Shiyuan Zhong ◽

Timo Vihma

Keyword(s):

Global Warming ◽

Sea Ice ◽

North Pacific ◽

Arctic Sea Ice ◽

The Arctic ◽

Boreal Summer ◽

The North ◽

Arctic Sea ◽

Arctic Sea Ice Loss ◽

The North Pacific

Abstract. Arctic sea ice decrease in extent in recent decades has been linked to sea surface temperature (SST) anomalies in the North Pacific Ocean. In this study, we assess the relative contributions of the two leading modes in North Pacific SST anomalies representing external forcing related to global warming and internal forcing related to Pacific Decadal Oscillation (PDO) to the Arctic sea ice loss in boreal summer and autumn. For the 1979–2017 period, the time series of the global warming and PDO modes show significant positive and negative trends, respectively. The global warming mode accounts for 44.9 % and 50.1 % of the Arctic sea ice loss in boreal summer and autumn during this period, compared to the 20.0 % and 22.2 % from the PDO mode. There is also a seasonal difference in the response of atmospheric circulations to the two modes. The PDO mode excites a wavetrain from North Pacific to the Arctic; the wavetrain is not seen in the response of atmospheric circulation to the global warming mode. Both dynamic and thermodynamic forcings work in the relationship of atmospheric circulation and sea ice anomalies.

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Viral emergence in marine mammals in the North Pacific may be linked to Arctic sea ice reduction

Scientific Reports ◽

10.1038/s41598-019-51699-4 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 7

Author(s):

E. VanWormer ◽

J. A. K. Mazet ◽

A. Hall ◽

V. A. Gill ◽

P. L. Boveng ◽

...

Keyword(s):

Pacific Ocean ◽

Sea Ice ◽

North Pacific ◽

Marine Mammals ◽

North Pacific Ocean ◽

Arctic Sea Ice ◽

Sea Ice Extent ◽

The North ◽

Arctic Sea ◽

The North Pacific

Abstract Climate change-driven alterations in Arctic environments can influence habitat availability, species distributions and interactions, and the breeding, foraging, and health of marine mammals. Phocine distemper virus (PDV), which has caused extensive mortality in Atlantic seals, was confirmed in sea otters in the North Pacific Ocean in 2004, raising the question of whether reductions in sea ice could increase contact between Arctic and sub-Arctic marine mammals and lead to viral transmission across the Arctic Ocean. Using data on PDV exposure and infection and animal movement in sympatric seal, sea lion, and sea otter species sampled in the North Pacific Ocean from 2001–2016, we investigated the timing of PDV introduction, risk factors associated with PDV emergence, and patterns of transmission following introduction. We identified widespread exposure to and infection with PDV across the North Pacific Ocean beginning in 2003 with a second peak of PDV exposure and infection in 2009; viral transmission across sympatric marine mammal species; and association of PDV exposure and infection with reductions in Arctic sea ice extent. Peaks of PDV exposure and infection following 2003 may reflect additional viral introductions among the diverse marine mammals in the North Pacific Ocean linked to change in Arctic sea ice extent.

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