Weak Stratospheric Polar Vortex Events Modulated by the Arctic Sea‐Ice Loss

Abstract The loss of Arctic sea ice is already having profound environmental, societal, and ecological impacts locally. A highly uncertain area of scientific research, however, is whether such Arctic change has a tangible effect on weather and climate at lower latitudes. There is emerging evidence that the geographical location of sea ice loss is critically important in determining the large-scale atmospheric circulation response and associated midlatitude impacts. However, such regional dependencies have not been explored in a thorough and systematic manner. To make progress on this issue, this study analyzes ensemble simulations with an atmospheric general circulation model prescribed with sea ice loss separately in nine regions of the Arctic, to elucidate the distinct responses to regional sea ice loss. The results suggest that in some regions, sea ice loss triggers large-scale dynamical responses, whereas in other regions sea ice loss induces only local thermodynamical changes. Sea ice loss in the Barents–Kara Seas is unique in driving a weakening of the stratospheric polar vortex, followed in time by a tropospheric circulation response that resembles the North Atlantic Oscillation. For October–March, the largest spatial-scale responses are driven by sea ice loss in the Barents–Kara Seas and the Sea of Okhotsk; however, different regions assume greater importance in other seasons. The atmosphere responds very differently to regional sea ice losses than to pan-Arctic sea ice loss, and the response to pan-Arctic sea ice loss cannot be obtained by the linear addition of the responses to regional sea ice losses. The results imply that diversity in past studies of the simulated response to Arctic sea ice loss can be partly explained by the different spatial patterns of sea ice loss imposed.

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Isolating the Atmospheric Circulation Response to Arctic Sea Ice Loss in the Coupled Climate System

Journal of Climate ◽

10.1175/jcli-d-16-0257.1 ◽

2017 ◽

Vol 30 (6) ◽

pp. 2163-2185 ◽

Cited By ~ 54

Author(s):

Russell Blackport ◽

Paul J. Kushner

Keyword(s):

Sea Ice ◽

Polar Vortex ◽

Arctic Sea Ice ◽

Low Latitude ◽

Stratospheric Polar Vortex ◽

Sea Level Pressure ◽

Surface Warming ◽

Arctic Sea ◽

Pressure Anomaly ◽

Arctic Sea Ice Loss

Abstract In this study, coupled ocean–atmosphere–land–sea ice Earth system model (ESM) simulations driven separately by sea ice albedo reduction and by projected greenhouse-dominated radiative forcing are combined to cleanly isolate the sea ice loss response of the atmospheric circulation. A pattern scaling approach is proposed in which the local multidecadal mean atmospheric response is assumed to be separately proportional to the total sea ice loss and to the total low-latitude ocean surface warming. The proposed approach estimates the response to Arctic sea ice loss with low-latitude ocean temperatures fixed and vice versa. The sea ice response includes a high northern latitude easterly zonal wind response, an equatorward shift of the eddy-driven jet, a weakening of the stratospheric polar vortex, an anticyclonic sea level pressure anomaly over coastal Eurasia, a cyclonic sea level pressure anomaly over the North Pacific, and increased wintertime precipitation over the west coast of North America. Many of these responses are opposed by the response to low-latitude surface warming with sea ice fixed. However, both sea ice loss and low-latitude surface warming act in concert to reduce subseasonal temperature variability throughout the middle and high latitudes. The responses are similar in two related versions of the National Center for Atmospheric Research Earth system models, apart from the stratospheric polar vortex response. Evidence is presented that internal variability can easily contaminate the estimates if not enough independent climate states are used to construct them.

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Weakening of the stratospheric polar vortex by Arctic sea-ice loss

Nature Communications ◽

10.1038/ncomms5646 ◽

2014 ◽

Vol 5 (1) ◽

Cited By ~ 304

Author(s):

Baek-Min Kim ◽

Seok-Woo Son ◽

Seung-Ki Min ◽

Jee-Hoon Jeong ◽

Seong-Joong Kim ◽

...

Keyword(s):

Sea Ice ◽

Polar Vortex ◽

Arctic Sea Ice ◽

Stratospheric Polar Vortex ◽

Arctic Sea ◽

Arctic Sea Ice Loss

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Model and state dependence of the atmospheric response to Arctic sea-ice loss

10.5194/egusphere-egu2020-11872 ◽

2020 ◽

Author(s):

Amber Walsh ◽

James Screen ◽

Adam Scaife ◽

Doug Smith ◽

Rosie Eade

Keyword(s):

Sea Ice ◽

Polar Vortex ◽

Horizontal Resolution ◽

Arctic Sea Ice ◽

Atmospheric Response ◽

Model Resolution ◽

Quasi Biennial Oscillation ◽

Stratospheric Polar Vortex ◽

Arctic Sea ◽

Arctic Sea Ice Loss

The climate response to Arctic sea-ice loss is highly uncertain. There exists considerable disagreement between observational and modelling studies, and between models, for reasons that remain poorly understood. To make progress, the Polar Amplification Model Intercomparison Project (PAMIP) was designed to provide coordinated experiments, with consistent sea-ice loss applied in multiple models. Results from the PAMIP are presented, focussing on the robustness of the atmospheric response to Arctic sea-ice loss across models and, within individual models, the dependence of the response on the mean state.In the troposphere, the mid-latitude jet is either weakened and/or shifted towards the equator in all models, albeit with varying magnitudes. We hypothesise that the magnitude of the jet response is sensitive to the atmospheric model resolution. To test this, and to more broadly identify the aspects of the atmospheric response that are sensitive to model resolution, we compare like-for-like experiments with two versions of the HadGEM3 model at low (N96) and high (N216) horizontal resolution.The stratospheric polar vortex response to Arctic sea-ice loss is not consistent between models, and appears to be influenced by both the size of the ensemble for each model and the phase of the Quasi-Biennial Oscillation (QBO). The possible modulating effect of the QBO is further explored using new simulations with background atmospheric states representing the easterly and westerly QBO phases.A surprising early result from the PAMIP simulations were sizeable changes in the Southern Hemisphere in response to Arctic sea-ice loss and significant changes in the Northern Hemisphere in response to Antarctic sea-ice loss, even in atmosphere-only model experiments. The robustness of such apparent interhemispheric connections across models, ensemble sizes and mean states is investigated.&#160;&#160;&#160;

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Intraseasonal and Interdecadal Jet Shifts in the Northern Hemisphere: The Role of Warm Pool Tropical Convection and Sea Ice

Journal of Climate ◽

10.1175/jcli-d-14-00057.1 ◽

2014 ◽

Vol 27 (17) ◽

pp. 6497-6518 ◽

Cited By ~ 49

Author(s):

Steven B. Feldstein ◽

Sukyoung Lee

Keyword(s):

Sea Ice ◽

Polar Vortex ◽

Warm Pool ◽

Wave Activity ◽

Arctic Sea Ice ◽

Tropical Convection ◽

The Arctic ◽

Stratospheric Polar Vortex ◽

Arctic Sea ◽

Wave Activity Flux

Abstract This study uses cluster analysis to investigate the interdecadal poleward shift of the subtropical and eddy-driven jets and its relationship to intraseasonal teleconnections. For this purpose, self-organizing map (SOM) analysis is applied to the ECMWF Interim Re-Analysis (ERA-Interim) zonal-mean zonal wind. The resulting SOM patterns have time scales of 4.8–5.7 days and undergo notable interdecadal trends in their frequency of occurrence. The sum of these trends closely resembles the observed interdecadal trend of the subtropical and eddy-driven jets, indicating that much of the interdecadal climate forcing is manifested through changes in the frequency of intraseasonal teleconnection patterns. Two classes of jet cluster patterns are identified. The first class of SOM pattern is preceded by anomalies in convection over the warm pool followed by changes in the poleward wave activity flux. The second class of patterns is preceded by sea ice and stratospheric polar vortex anomalies; when the Arctic sea ice area is reduced, the subsequent planetary wave anomalies destructively interfere with the climatological stationary waves. This is followed by a decrease in the vertical wave activity flux and a strengthening of the stratospheric polar vortex. An increase in sea ice area leads to the opposite chain of events. Analysis suggests that the positive trend in the Arctic Oscillation (AO) up until the early 1990s might be attributed to increased warm pool tropical convection, while the subsequent reversal in its trend may be due to the influence of tropical convection being overshadowed by the accelerated loss of Arctic sea ice.

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Mechanisms causing reduced Arctic sea ice loss in a coupled climate model

The Cryosphere Discussions ◽

10.5194/tcd-6-2653-2012 ◽

2012 ◽

Vol 6 (4) ◽

pp. 2653-2687 ◽

Cited By ~ 1

Author(s):

A. E. West ◽

A. B. Keen ◽

H. T. Hewitt

Keyword(s):

Sea Ice ◽

Climate Model ◽

Historical Record ◽

Arctic Sea Ice ◽

The Arctic ◽

Slight Reduction ◽

Coupled Climate Model ◽

Arctic Sea ◽

Ensembles Project ◽

Arctic Sea Ice Loss

Abstract. The fully-coupled climate model HadGEM1 produces one of the most accurate simulations of the historical record of Arctic sea ice seen in the IPCC AR4 multi-model ensemble. In this study, we examine projections of sea ice decline out to 2030, produced by two ensembles of HadGEM1 with natural and anthropogenic forcings included. These ensembles project a significant slowing of the rate of ice loss to occur after 2010, with some integrations even simulating a small increase in ice area. We use an energy budget of the Arctic to examine the causes of this slowdown. A negative feedback effect by which rapid reductions in ice thickness north of Greenland reduce ice export is found to play a major role. A slight reduction in ocean-to-ice heat flux in the relevant period, caused by changes in the MOC and subpolar gyre in some integrations, is also found to play a part. Finally, we assess the likelihood of a slowdown occurring in the real world due to these causes.

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Greenhouse-gas contribution to Arctic sea-ice loss

10.5194/egusphere-egu21-3720 ◽

2021 ◽

Author(s):

Yeon-Hee Kim ◽

Seung-Ki Min

Keyword(s):

Sea Ice ◽

Greenhouse Gas ◽

Coupled Model ◽

Arctic Sea Ice ◽

The Arctic ◽

Detection Analysis ◽

External Forcings ◽

Arctic Sea ◽

Intercomparison Project ◽

Arctic Sea Ice Loss

Arctic sea-ice area (ASIA) has been declining rapidly throughout the year during recent decades, but a formal quantification of greenhouse gas (GHG) contribution remains limited. This study conducts an attribution analysis of the observed ASIA changes from 1979 to 2017 by comparing three satellite observations with the Coupled Model Intercomparison Project Phase 6 (CMIP6) multi-model simulations using an optimal fingerprint method. The observed ASIA exhibits overall decreasing trends across all months with stronger trends in warm seasons. CMIP6 anthropogenic plus natural forcing (ALL) simulations and GHG-only forcing simulations successfully capture the observed temporal trend patterns. Results from detection analysis show that ALL signals are detected robustly for all calendar months for three observations. It is found that GHG signals are detectable in the observed ASIA decrease throughout the year, explaining most of the ASIA reduction, with a much weaker contribution by other external forcings. We additionally find that the Arctic Ocean will occur ice-free in September around the 2040s regardless of the emission scenario.

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The Robustness of Midlatitude Weather Pattern Changes due to Arctic Sea Ice Loss

Journal of Climate ◽

10.1175/jcli-d-16-0167.1 ◽

2016 ◽

Vol 29 (21) ◽

pp. 7831-7849 ◽

Cited By ~ 34

Author(s):

Hans W. Chen ◽

Fuqing Zhang ◽

Richard B. Alley

Keyword(s):

Sea Ice ◽

Large Scale ◽

Coupled System ◽

Circulation Pattern ◽

Ice Cover ◽

Arctic Sea Ice ◽

The Arctic ◽

Intrinsic Variability ◽

Arctic Sea ◽

Arctic Sea Ice Loss

Abstract The significance and robustness of the link between Arctic sea ice loss and changes in midlatitude weather patterns is investigated through a series of model simulations from the Community Atmosphere Model, version 5.3, with systematically perturbed sea ice cover in the Arctic. Using a large ensemble of 10 sea ice scenarios and 550 simulations, it is found that prescribed Arctic sea ice anomalies produce statistically significant changes for certain metrics of the midlatitude circulation but not for others. Furthermore, the significant midlatitude circulation changes do not scale linearly with the sea ice anomalies and are not present in all scenarios, indicating that the remote atmospheric response to reduced Arctic sea ice can be statistically significant under certain conditions but is generally nonrobust. Shifts in the Northern Hemisphere polar jet stream and changes in the meridional extent of upper-level large-scale waves due to the sea ice perturbations are generally small and not clearly distinguished from intrinsic variability. Reduced Arctic sea ice may favor a circulation pattern that resembles the negative phase of the Arctic Oscillation and may increase the risk of cold outbreaks in eastern Asia by almost 50%, but this response is found in only half of the scenarios with negative sea ice anomalies. In eastern North America the frequency of extreme cold events decreases almost linearly with decreasing sea ice cover. This study’s finding of frequent significant anomalies without a robust linear response suggests interactions between variability and persistence in the coupled system, which may contribute to the lack of convergence among studies of Arctic influences on midlatitude circulation.

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The Seasonal Atmospheric Response to Projected Arctic Sea Ice Loss in the Late Twenty-First Century

Journal of Climate ◽

10.1175/2009jcli3053.1 ◽

2010 ◽

Vol 23 (2) ◽

pp. 333-351 ◽

Cited By ~ 330

Author(s):

Clara Deser ◽

Robert Tomas ◽

Michael Alexander ◽

David Lawrence

Keyword(s):

Sea Ice ◽

High Latitude ◽

Vertical Structure ◽

Arctic Sea Ice ◽

First Century ◽

The Arctic ◽

Arctic Sea ◽

Ice Conditions ◽

Twenty First Century ◽

Arctic Sea Ice Loss

Abstract The authors investigate the atmospheric response to projected Arctic sea ice loss at the end of the twenty-first century using an atmospheric general circulation model (GCM) coupled to a land surface model. The response was obtained from two 60-yr integrations: one with a repeating seasonal cycle of specified sea ice conditions for the late twentieth century (1980–99) and one with that of sea ice conditions for the late twenty-first century (2080–99). In both integrations, a repeating seasonal cycle of SSTs for 1980–99 was prescribed to isolate the impact of projected future sea ice loss. Note that greenhouse gas concentrations remained fixed at 1980–99 levels in both sets of experiments. The twentieth- and twenty-first-century sea ice (and SST) conditions were obtained from ensemble mean integrations of a coupled GCM under historical forcing and Special Report on Emissions Scenarios (SRES) A1B scenario forcing, respectively. The loss of Arctic sea ice is greatest in summer and fall, yet the response of the net surface energy budget over the Arctic Ocean is largest in winter. Air temperature and precipitation responses also maximize in winter, both over the Arctic Ocean and over the adjacent high-latitude continents. Snow depths increase over Siberia and northern Canada because of the enhanced winter precipitation. Atmospheric warming over the high-latitude continents is mainly confined to the boundary layer (below ∼850 hPa) and to regions with a strong low-level temperature inversion. Enhanced warm air advection by submonthly transient motions is the primary mechanism for the terrestrial warming. A significant large-scale atmospheric circulation response is found during winter, with a baroclinic (equivalent barotropic) vertical structure over the Arctic in November–December (January–March). This response resembles the negative phase of the North Atlantic Oscillation in February only. Comparison with the fully coupled model reveals that Arctic sea ice loss accounts for most of the seasonal, spatial, and vertical structure of the high-latitude warming response to greenhouse gas forcing at the end of the twenty-first century.

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Internal Variability in Projections of Twenty-First-Century Arctic Sea Ice Loss: Role of the Large-Scale Atmospheric Circulation

Journal of Climate ◽

10.1175/jcli-d-12-00839.1 ◽

2014 ◽

Vol 27 (2) ◽

pp. 527-550 ◽

Cited By ~ 53

Author(s):

Justin J. Wettstein ◽

Clara Deser

Keyword(s):

Sea Ice ◽

Atmospheric Circulation ◽

Large Scale ◽

Wave Train ◽

Internal Variability ◽

Arctic Sea Ice ◽

The Arctic ◽

Arctic Sea ◽

Rossby Wave Train ◽

Arctic Sea Ice Loss

Abstract Internal variability in twenty-first-century summer Arctic sea ice loss and its relationship to the large-scale atmospheric circulation is investigated in a 39-member Community Climate System Model, version 3 (CCSM3) ensemble for the period 2000–61. Each member is subject to an identical greenhouse gas emissions scenario and differs only in the atmospheric model component's initial condition. September Arctic sea ice extent trends during 2020–59 range from −2.0 × 106 to −5.7 × 106 km2 across the 39 ensemble members, indicating a substantial role for internal variability in future Arctic sea ice loss projections. A similar nearly threefold range (from −7.0 × 103 to −19 × 103 km3) is found for summer sea ice volume trends. Higher rates of summer Arctic sea ice loss in CCSM3 are associated with enhanced transpolar drift and Fram Strait ice export driven by surface wind and sea level pressure patterns. Over the Arctic, the covarying atmospheric circulation patterns resemble the so-called Arctic dipole, with maximum amplitude between April and July. Outside the Arctic, an atmospheric Rossby wave train over the Pacific sector is associated with internal ice loss variability. Interannual covariability patterns between sea ice and atmospheric circulation are similar to those based on trends, suggesting that similar processes govern internal variability over a broad range of time scales. Interannual patterns of CCSM3 ice–atmosphere covariability compare well with those in nature and in the newer CCSM4 version of the model, lending confidence to the results. Atmospheric teleconnection patterns in CCSM3 suggest that the tropical Pacific modulates Arctic sea ice variability via the aforementioned Rossby wave train. Large ensembles with other coupled models are needed to corroborate these CCSM3-based findings.

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