scholarly journals Low-frequency variability of the arctic climate: the role of oceanic and atmospheric heat transport variations

2009 ◽  
Vol 34 (2-3) ◽  
pp. 265-279 ◽  
Author(s):  
Johann H. Jungclaus ◽  
Torben Koenigk
Keyword(s):  
Heat Transport ◽  
Low Frequency ◽  
Arctic Climate ◽  
The Arctic ◽  
Low Frequency Variability ◽  
Atmospheric Heat Transport ◽  
Atmospheric Heat

The role of atmospheric heat transport and regional feedbacks in the Arctic warming at equilibrium

2017 ◽  
Vol 49 (9-10) ◽  
pp. 3457-3472 ◽  
Author(s):  
Masakazu Yoshimori ◽  
Ayako Abe-Ouchi ◽  
Alexandre Laîné
Keyword(s):  
Heat Transport ◽  
The Arctic ◽  
Arctic Warming ◽  
Atmospheric Heat Transport ◽  
Atmospheric Heat

scholarly journals Mechanisms for low-frequency variability of summer Arctic sea ice extent

2015 ◽  
Vol 112 (15) ◽  
pp. 4570-4575 ◽  
Author(s):  
Rong Zhang
Keyword(s):  
Sea Ice ◽  
Heat Transport ◽  
Low Frequency ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Low Frequency Variability ◽  
Sea Ice Decline ◽  
Arctic Sea ◽  
Arctic Sea Ice Extent

Satellite observations reveal a substantial decline in September Arctic sea ice extent since 1979, which has played a leading role in the observed recent Arctic surface warming and has often been attributed, in large part, to the increase in greenhouse gases. However, the most rapid decline occurred during the recent global warming hiatus period. Previous studies are often focused on a single mechanism for changes and variations of summer Arctic sea ice extent, and many are based on short observational records. The key players for summer Arctic sea ice extent variability at multidecadal/centennial time scales and their contributions to the observed summer Arctic sea ice decline are not well understood. Here a multiple regression model is developed for the first time, to the author’s knowledge, to provide a framework to quantify the contributions of three key predictors (Atlantic/Pacific heat transport into the Arctic, and Arctic Dipole) to the internal low-frequency variability of Summer Arctic sea ice extent, using a 3,600-y-long control climate model simulation. The results suggest that changes in these key predictors could have contributed substantially to the observed summer Arctic sea ice decline. If the ocean heat transport into the Arctic were to weaken in the near future due to internal variability, there might be a hiatus in the decline of September Arctic sea ice. The modeling results also suggest that at multidecadal/centennial time scales, variations in the atmosphere heat transport across the Arctic Circle are forced by anticorrelated variations in the Atlantic heat transport into the Arctic.

scholarly journals Coupled High-Latitude Climate Feedbacks and Their Impact on Atmospheric Heat Transport

2017 ◽  
Vol 30 (1) ◽  
pp. 189-201 ◽  
Author(s):  
Nicole Feldl ◽  
Simona Bordoni ◽  
Timothy M. Merlis
Keyword(s):  
Heat Transport ◽  
High Latitude ◽  
Surface Albedo ◽  
Hadley Cell ◽  
Lapse Rate ◽  
The Arctic ◽  
Albedo Feedback ◽  
Atmospheric Heat Transport ◽  
The Tropics ◽  
Atmospheric Heat

The response of atmospheric heat transport to anthropogenic warming is determined by the anomalous meridional energy gradient. Feedback analysis offers a characterization of that gradient and hence reveals how uncertainty in physical processes may translate into uncertainty in the circulation response. However, individual feedbacks do not act in isolation. Anomalies associated with one feedback may be compensated by another, as is the case for the positive water vapor and negative lapse rate feedbacks in the tropics. Here a set of idealized experiments are performed in an aquaplanet model to evaluate the coupling between the surface albedo feedback and other feedbacks, including the impact on atmospheric heat transport. In the tropics, the dynamical response manifests as changes in the intensity and structure of the overturning Hadley circulation. Only half of the range of Hadley cell weakening exhibited in these experiments is found to be attributable to imposed, systematic variations in the surface albedo feedback. Changes in extratropical clouds that accompany the albedo changes explain the remaining spread. The feedback-driven circulation changes are compensated by eddy energy flux changes, which reduce the overall spread among experiments. These findings have implications for the efficiency with which the climate system, including tropical circulation and the hydrological cycle, adjusts to high-latitude feedbacks over climate states that range from perennial or seasonal ice to ice-free conditions in the Arctic.

scholarly journals Comparison of Mechanisms for Low-Frequency Variability of Summer Arctic Sea Ice in Three Coupled Models

2018 ◽  
Vol 31 (3) ◽  
pp. 1205-1226 ◽  
Author(s):  
Dawei Li ◽  
Rong Zhang ◽  
Thomas Knutson
Keyword(s):  
Sea Ice ◽  
Heat Transport ◽  
Low Frequency ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Coupled Models ◽  
Surface Warming ◽  
Low Frequency Variability ◽  
Sea Ice Decline ◽  
Arctic Sea

Abstract In this study the mechanisms for low-frequency variability of summer Arctic sea ice are analyzed using long control simulations from three coupled models (GFDL CM2.1, GFDL CM3, and NCAR CESM). Despite different Arctic sea ice mean states, there are many robust features in the response of low-frequency summer Arctic sea ice variability to the three key predictors (Atlantic and Pacific oceanic heat transport into the Arctic and the Arctic dipole) across all three models. In all three models, an enhanced Atlantic (Pacific) heat transport into the Arctic induces summer Arctic sea ice decline and surface warming, especially over the Atlantic (Pacific) sector of the Arctic. A positive phase of the Arctic dipole induces summer Arctic sea ice decline and surface warming on the Pacific side, and opposite changes on the Atlantic side. There is robust Bjerknes compensation at low frequency, so the northward atmospheric heat transport provides a negative feedback to summer Arctic sea ice variations. The influence of the Arctic dipole on summer Arctic sea ice extent is more (less) effective in simulations with less (excessive) climatological summer sea ice in the Atlantic sector. The response of Arctic sea ice thickness to the three key predictors is stronger in models that have thicker climatological Arctic sea ice.

scholarly journals Empirical Mode Reduction in a Model of Extratropical Low-Frequency Variability

2006 ◽  
Vol 63 (7) ◽  
pp. 1859-1877 ◽  
Author(s):  
D. Kondrashov ◽  
S. Kravtsov ◽  
M. Ghil
Keyword(s):  
Numerical Study ◽  
Singular Spectrum Analysis ◽  
Low Frequency ◽  
The Arctic ◽  
Reduced Model ◽  
The North ◽  
Low Frequency Variability ◽  
Intraseasonal Oscillations ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

Abstract This paper constructs and analyzes a reduced nonlinear stochastic model of extratropical low-frequency variability. To do so, it applies multilevel quadratic regression to the output of a long simulation of a global baroclinic, quasigeostrophic, three-level (QG3) model with topography; the model's phase space has a dimension of O(104). The reduced model has 45 variables and captures well the non-Gaussian features of the QG3 model's probability density function (PDF). In particular, the reduced model's PDF shares with the QG3 model its four anomalously persistent flow patterns, which correspond to opposite phases of the Arctic Oscillation and the North Atlantic Oscillation, as well as the Markov chain of transitions between these regimes. In addition, multichannel singular spectrum analysis identifies intraseasonal oscillations with a period of 35–37 days and of 20 days in the data generated by both the QG3 model and its low-dimensional analog. An analytical and numerical study of the reduced model starts with the fixed points and oscillatory eigenmodes of the model's deterministic part and uses systematically an increasing noise parameter to connect these with the behavior of the full, stochastically forced model version. The results of this study point to the origin of the QG3 model's multiple regimes and intraseasonal oscillations and identify the connections between the two types of behavior.

scholarly journals Atmospheric Circulation Regimes in a Nonlinear Quasi-Geostrophic Model

2015 ◽  
Vol 2015 ◽  
pp. 1-19 ◽  
Author(s):  
Henriette Labsch ◽  
Dörthe Handorf ◽  
Klaus Dethloff ◽  
Michael V. Kurgansky
Keyword(s):  
Atmospheric Circulation ◽  
Arctic Oscillation ◽  
Significant Contribution ◽  
Decadal Variability ◽  
Low Frequency ◽  
The Arctic ◽  
Satisfactory Model ◽  
Low Frequency Variability ◽  
Interannual And Decadal Variability ◽  
The Arctic Oscillation

Atmospheric low-frequency variability and circulation regime behavior are investigated in the context of a quasi-geostrophic (QG) three-level T63 model of the wintertime atmospheric circulation over the Northern Hemisphere (NH). The model generates strong interannual and decadal variability, with the domination of the annular mode of variability. It successfully reproduces a satisfactory model climatology and the most important atmospheric circulation regimes. The positive phase of the Arctic Oscillation is a robust feature of the quasi-geostrophic T63 model. The model results based on QG dynamics underlie atmospheric regime behavior in the extratropical NH and suggest that nonlinear internal processes deliver significant contribution to the atmospheric climate variability on interannual and decadal timescales.

Rebalancing state and Indigenous sovereignties in international law: An Arctic lens on trajectories for global governance

2019 ◽  
Vol 32 (4) ◽  
pp. 675-693
Author(s):  
Sabaa Ahmad Khan
Keyword(s):  
Climate Change ◽  
International Law ◽  
Indigenous Peoples ◽  
Global Governance ◽  
Anthropogenic Activities ◽  
International System ◽  
Arctic Climate ◽  
The Arctic ◽  
Arctic Climate Change

AbstractThe environmental and economic realities of Arctic climate change present novel problems for international law. Arctic warming and pollution raise important questions about responsibilities and accountabilities across borders, as they result from anthropogenic activities both within and outside the Arctic region, from the Global North and the Global South. Environmental interdependencies and economic development prospects connect in a nexus of risk and opportunity that raises difficult normative questions pertaining to Arctic governance and sovereignty. This article looks at how the Arctic has been produced in international legal spaces. It addresses the implication of states and Indigenous peoples in processes of Arctic governance. Looking at specific international legal instruments relevant to Arctic climate change and development, the author attempts to tease out the relationship between the concepts of Indigenous rights and state sovereignty that underlie these international legal realms. What do these international legal regimes tell us with respect to the role of Arctic Indigenous peoples and the role of states in governing the ‘global’ Arctic? It is argued that while international law has come a long way in recognizing the special status of Indigenous peoples in the international system, it still hesitates to recognize Indigenous groups as international law makers. Comparing the status of Indigenous peoples under specific international regimes to their role within the Arctic Council, it becomes evident that more participatory forms of global governance are entirely possible and long overdue.

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