Role of Arctic sea ice loss in autumn in the polar vortex splitting in winters 1984/1985, 1998/1999, and 2012/2013

Abstract The impact of projected Arctic sea ice loss on the atmospheric circulation is investigated using the Whole Atmosphere Community Climate Model (WACCM), a model with a well-resolved stratosphere. Two 160-yr simulations are conducted: one with surface boundary conditions fixed at late twentieth-century values and the other with identical conditions except for Arctic sea ice, which is prescribed at late twenty-first-century values. Their difference isolates the impact of future Arctic sea ice loss upon the atmosphere. The tropospheric circulation response to the imposed ice loss resembles the negative phase of the northern annular mode, with the largest amplitude in winter, while the less well-known stratospheric response transitions from a slight weakening of the polar vortex in winter to a strengthening of the vortex in spring. The lack of a significant winter stratospheric circulation response is shown to be a consequence of largely cancelling effects from sea ice loss in the Atlantic and Pacific sectors, which drive opposite-signed changes in upward wave propagation from the troposphere to the stratosphere. Identical experiments conducted with Community Atmosphere Model, version 4, WACCM’s low-top counterpart, show a weaker tropospheric response and a different stratospheric response compared to WACCM. An additional WACCM experiment in which the imposed ice loss is limited to August–November reveals that autumn ice loss weakens the stratospheric polar vortex in January, followed by a small but significant tropospheric response in late winter and early spring that resembles the negative phase of the North Atlantic Oscillation, with attendant surface climate impacts.

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The Role of Extratropical Ocean Warming in the Coupled Climate Response to Arctic Sea Ice Loss

Journal of Climate ◽

10.1175/jcli-d-18-0192.1 ◽

2018 ◽

Vol 31 (22) ◽

pp. 9193-9206 ◽

Cited By ~ 6

Author(s):

Russell Blackport ◽

Paul J. Kushner

Keyword(s):

Sea Ice ◽

Atmospheric Circulation ◽

General Circulation ◽

Arctic Sea Ice ◽

Ocean Warming ◽

The Arctic ◽

Climate Response ◽

Arctic Sea ◽

Arctic Sea Ice Loss

The role of extratropical ocean warming in the coupled climate response to Arctic sea ice loss is investigated using coupled atmosphere–ocean general circulation model (AOGCM) and uncoupled atmospheric-only (AGCM) experiments. Coupled AOGCM experiments driven by sea ice albedo reduction and greenhouse gas–dominated radiative forcing are used to diagnose the extratropical sea surface temperature (SST) response to sea ice loss. Sea ice loss is then imposed in AGCM experiments both with and without these extratropical SST changes, which are found to extend beyond the regions where sea ice is lost. Sea ice loss in isolation drives warming that is confined to the Arctic lower troposphere and only a weak atmospheric circulation response. When the extratropical SST response caused by sea ice loss is also included in the forcing, the warming extends into the Arctic midtroposphere during winter. This coincides with a stronger atmospheric circulation response, including an equatorward shift in the eddy-driven jet, a deepening of the Aleutian low, and an expansion of the Siberian high. Similar results are found whether the extratropical SST forcing is taken directly from the AOGCM driven by sea ice loss, or whether they are diagnosed using a two-parameter pattern scaling technique where tropical adjustment to sea ice loss is removed. These results suggest that AGCM experiments that are driven by sea ice loss and only local SST increases will underestimate the Arctic midtroposphere warming and atmospheric circulation response to sea ice loss, compared to AOGCM simulations and the real world.

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

Journal of Geophysical Research Atmospheres ◽

10.1029/2018jd029222 ◽

2019 ◽

Vol 124 (2) ◽

pp. 858-869 ◽

Cited By ~ 8

Author(s):

Kazuhira Hoshi ◽

Jinro Ukita ◽

Meiji Honda ◽

Tetsu Nakamura ◽

Koji Yamazaki ◽

...

Keyword(s):

Sea Ice ◽

Polar Vortex ◽

Arctic Sea Ice ◽

The Arctic ◽

Stratospheric Polar Vortex ◽

Arctic Sea ◽

Arctic Sea Ice Loss

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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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Elucidating the Role of Anthropogenic Aerosols in Arctic Sea Ice Variations

Journal of Climate ◽

10.1175/jcli-d-17-0287.1 ◽

2017 ◽

Vol 31 (1) ◽

pp. 99-114 ◽

Cited By ~ 14

Author(s):

Yuan Wang ◽

Jonathan H. Jiang ◽

Hui Su ◽

Yong-Sang Choi ◽

Lei Huang ◽

...

Keyword(s):

Sea Ice ◽

Radiative Forcing ◽

Arctic Sea Ice ◽

Arctic Climate ◽

The Arctic ◽

Particulate Pollution ◽

Arctic Sea ◽

Arctic Climate Change ◽

Arctic Sea Ice Loss

AbstractObservations show that the Arctic sea ice cover has been shrinking at an unprecedented rate since the 1970s. Even though the accumulation of greenhouse gases in the atmosphere has been closely linked with the loss of Arctic sea ice, the role of atmospheric aerosols in past and future Arctic climate change remains elusive. Using a state-of-the-art fully coupled climate model, the authors assess the equilibrium responses of the Arctic sea ice to the different aerosol emission scenarios and investigate the pathways by which aerosols impose their influence in the Arctic. These sensitivity experiments show that the impacts of aerosol perturbations on the pace of sea ice melt effectively modulate the ocean circulation and atmospheric feedbacks. Because of the contrasting evolutions of particulate pollution in the developed and developing countries since the 1970s, the opposite aerosol forcings from different midlatitude regions are nearly canceled out in the Arctic during the boreal summer, resulting in a muted aerosol effect on the recent sea ice changes. Consequently, the greenhouse forcing alone can largely explain the observed Arctic sea ice loss up to the present. In the next few decades, the projected alleviation of particulate pollution in the Northern Hemisphere can contribute up to 20% of the total Arctic sea ice loss and 0.7°C surface warming over the Arctic. The authors’ model simulations further show that aerosol microphysical effects on the Arctic clouds are the major component in the total aerosol radiative forcing over the Arctic. Compared to the aerosol-induced energy imbalance in lower latitudes outside the Arctic, the local radiative forcing by aerosol variations within the Arctic, due to either local emissions or long-range transports, is more efficient in determining the sea ice changes and Arctic climate change.

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