“Climate response functions” for the Arctic Ocean: a proposed coordinated modelling experiment

Abstract. A coordinated set of Arctic modelling experiments, which explore how the Arctic responds to changes in external forcing, is proposed. Our goal is to compute and compare climate response functions (CRFs) – the transient response of key observable indicators such as sea-ice extent, freshwater content of the Beaufort Gyre, etc. – to abrupt step changes in forcing fields across a number of Arctic models. Changes in wind, freshwater sources, and inflows to the Arctic basin are considered. Convolutions of known or postulated time series of these forcing fields with their respective CRFs then yield the (linear) response of these observables. This allows the project to inform, and interface directly with, Arctic observations and observers and the climate change community. Here we outline the rationale behind such experiments and illustrate our approach in the context of a coarse-resolution model of the Arctic based on the MITgcm. We conclude by summarizing the expected benefits of such an activity and encourage other modelling groups to compute CRFs with their own models so that we might begin to document their robustness to model formulation, resolution, and parameterization.

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'Climate Response Functions' for the Arctic Ocean: a proposed coordinated modeling experiment

10.5194/gmd-2016-316 ◽

2017 ◽

Cited By ~ 3

Author(s):

John Marshall ◽

Jeffery Scott ◽

Andrey Proshutinsky

Keyword(s):

Arctic Basin ◽

The Arctic ◽

Climate Response ◽

Response Functions ◽

Sea Ice Extent ◽

Beaufort Gyre ◽

Modeling Experiment ◽

Resolution Model ◽

Expected Benefits ◽

Climate Change Community

Abstract. A coordinated set of Arctic modeling experiments is proposed which explore how the Arctic responds to changes in external forcing. Our goal is to compute and compare 'Climate Response Functions' (CRFs) – the transient response of key observable indicators such as sea-ice extent, freshwater content of the Beaufort Gyre etc. – to abrupt 'step' changes in forcing fields across a number of Arctic models. Changes in wind, freshwater sources and inflows to the Arctic basin are considered. Convolutions of known or postulated time-series of these forcing fields with their respective CRFs then yields the (linear) response of these observables. This allows the project to inform, and interface directly with, Arctic observations and observers and IPCC models and the climate change community. Here we outline the rationale behind such experiments and illustrate our approach in the context of a coarse-resolution model of the Arctic based on the MITgcm. We conclude by outlining the expected benefits of such an activity and encourage other modeling groups to compute CRFs with their own models so that we might begin to document how robust they are to model formulation, resolution and parameterization.

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Arctic Ocean surface geostrophic circulation 2003–2014

The Cryosphere ◽

10.5194/tc-11-1767-2017 ◽

2017 ◽

Vol 11 (4) ◽

pp. 1767-1780 ◽

Cited By ~ 42

Author(s):

Thomas W. K. Armitage ◽

Sheldon Bacon ◽

Andy L. Ridout ◽

Alek A. Petty ◽

Steven Wolbach ◽

...

Keyword(s):

Arctic Ocean ◽

Decadal Variability ◽

Arctic Basin ◽

Ocean Surface ◽

Arctic Sea Ice ◽

The Arctic ◽

Atmospheric Forcing ◽

Geostrophic Currents ◽

Beaufort Gyre ◽

Gyre Circulation

Abstract. Monitoring the surface circulation of the ice-covered Arctic Ocean is generally limited in space, time or both. We present a new 12-year record of geostrophic currents at monthly resolution in the ice-covered and ice-free Arctic Ocean derived from satellite radar altimetry and characterise their seasonal to decadal variability from 2003 to 2014, a period of rapid environmental change in the Arctic. Geostrophic currents around the Arctic basin increased in the late 2000s, with the largest increases observed in summer. Currents in the southeastern Beaufort Gyre accelerated in late 2007 with higher current speeds sustained until 2011, after which they decreased to speeds representative of the period 2003–2006. The strength of the northwestward current in the southwest Beaufort Gyre more than doubled between 2003 and 2014. This pattern of changing currents is linked to shifting of the gyre circulation to the northwest during the time period. The Beaufort Gyre circulation and Fram Strait current are strongest in winter, modulated by the seasonal strength of the atmospheric circulation. We find high eddy kinetic energy (EKE) congruent with features of the seafloor bathymetry that are greater in winter than summer, and estimates of EKE and eddy diffusivity in the Beaufort Sea are consistent with those predicted from theoretical considerations. The variability of Arctic Ocean geostrophic circulation highlights the interplay between seasonally variable atmospheric forcing and ice conditions, on a backdrop of long-term changes to the Arctic sea ice–ocean system. Studies point to various mechanisms influencing the observed increase in Arctic Ocean surface stress, and hence geostrophic currents, in the 2000s – e.g. decreased ice concentration/thickness, changing atmospheric forcing, changing ice pack morphology; however, more work is needed to refine the representation of atmosphere–ice–ocean coupling in models before we can fully attribute causality to these increases.

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Sea ice inertial oscillations in the Arctic Basin

The Cryosphere ◽

10.5194/tc-6-1187-2012 ◽

2012 ◽

Vol 6 (5) ◽

pp. 1187-1201 ◽

Cited By ~ 22

Author(s):

F. Gimbert ◽

D. Marsan ◽

J. Weiss ◽

N. C. Jourdain ◽

B. Barnier

Keyword(s):

Sea Ice ◽

Arctic Basin ◽

Original Method ◽

The Arctic ◽

Ice Thickness ◽

Inertial Motion ◽

Inertial Oscillations ◽

Dimensional Parameter ◽

Sea Ice Extent ◽

Sea Ice Thickness

Abstract. An original method to quantify the amplitude of inertial motion of oceanic and ice drifters, through the introduction of a non-dimensional parameter M defined from a spectral analysis, is presented. A strong seasonal dependence of the magnitude of sea ice inertial oscillations is revealed, in agreement with the corresponding annual cycles of sea ice extent, concentration, thickness, advection velocity, and deformation rates. The spatial pattern of the magnitude of the sea ice inertial oscillations over the Arctic Basin is also in agreement with the sea ice thickness and concentration patterns. This argues for a strong interaction between the magnitude of inertial motion on one hand, the dissipation of energy through mechanical processes, and the cohesiveness of the cover on the other hand. Finally, a significant multi-annual evolution towards greater magnitudes of inertial oscillations in recent years, in both summer and winter, is reported, thus concomitant with reduced sea ice thickness, concentration and spatial extent.

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Fram Strait sea ice export variability and September Arctic sea ice extent over the last 80 years

10.5194/tc-2016-79 ◽

2016 ◽

Cited By ~ 2

Author(s):

Lars H. Smedsrud ◽

Mari H. Halvorsen ◽

Julienne C. Stroeve ◽

Rong Zhang ◽

Kjell Kloster

Keyword(s):

Sea Ice ◽

Arctic Basin ◽

Recent Decade ◽

Arctic Sea Ice ◽

The Arctic ◽

Fram Strait ◽

Sea Ice Extent ◽

Arctic Sea ◽

Arctic Sea Ice Extent

Abstract. The Arctic Basin exports between 600,000 and 1 million km2 of it's sea ice cover southwards through Fram Strait each year, or about 10 % of the sea-ice covered area inside the basin. During winter, ice export results in growth of new and relatively thin ice inside the basin, while during summer or spring, export contributes directly to open water further north that enhances the ice-albedo feedback during summer. A new updated time series from 1935 to 2014 of Fram Strait sea ice area export shows that the long-term annual mean export is about 880,000 km2, with large inter-annual and multidecadal variability, and no long-term trend over the past 80 years. Nevertheless, the last decade has witnessed increased ice export, with several years having annual ice export that exceed 1 million km2. Evaluating the trend onwards from 1979, when satellite based sea ice coverage became more readily available, reveals an increase in annual export of about +6 % per decade. The observed increase is caused by higher southward ice drift speeds due to stronger southward geostrophic winds, largely explained by increasing surface pressure over Greenland. Spring and summer area export increased more (+11 % per decade) than in autumn and winter (+2.6 % per decade). Contrary to the last decade, the 1950–1970 period had relatively low export during spring and summer, and consistently mid-September sea ice extent was higher during these decades than both before and afterwards. We thus find that export anomalies during spring have a clear influence on the following September sea ice extent in general, and that for the recent decade, the export may be partially responsible for the accelerating decline in Arctic sea ice extent.

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Arctic Ocean geostrophic circulation 2003-2014

10.5194/tc-2017-22 ◽

2017 ◽

Cited By ~ 5

Author(s):

Thomas W. K. Armitage ◽

Sheldon Bacon ◽

Andy L. Ridout ◽

Alek A. Petty ◽

Steven Wolbach ◽

...

Keyword(s):

Arctic Ocean ◽

Decadal Variability ◽

Arctic Basin ◽

Arctic Sea Ice ◽

The Arctic ◽

Atmospheric Forcing ◽

Geostrophic Currents ◽

Beaufort Gyre ◽

Ice Conditions ◽

Gyre Circulation

Abstract. Monitoring the surface circulation of the ice-covered Arctic Ocean is generally limited in space, time or both. We present a new 12-year record of geostrophic currents at monthly resolution in the ice-covered and ice-free Arctic Ocean and characterise their seasonal to decadal variability from 2003-2014, a period of rapid environmental change in the Arctic. Geostrophic currents around the Arctic basin increased in the late '00s, with the largest increases observed in summer. Currents in the southeastern Beaufort gyre accelerated in late 2007 with higher current speeds sustained until 2011, after which they decreased to speeds representative of the period 2003-2006. The strength of the northwestward current in the southwest Beaufort gyre more than doubled between 2003 and 2014. This pattern of changing currents is linked to shifting of the gyre circulation to the northwest during the time period. The Beaufort gyre circulation and Fram Strait current are strongest in winter, modulated by the seasonal strength of the atmospheric circulation. Eddy kinetic energy is also larger in winter and we find high eddy activity congruent with features of the seafloor bathymetry. The variability of Arctic Ocean geostrophic circulation highlights the interplay between seasonally variable atmospheric forcing and ice conditions, on a backdrop of long term changes to the Arctic sea ice-ocean system. Studies point to various mechanisms influencing the observed increase in Arctic Ocean surface stress, and hence geostrophic currents, in the '00s – e.g. decreased ice concentration/thickness, changing atmospheric forcing, changing ice pack morphology – however more work is needed to refine the representation of atmosphere-ice-ocean coupling in models before we can fully attribute causality to these increases.

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The Recent Decline of the Arctic Summer Sea-Ice Cover in the Context of Internal Climate Variability

The Open Atmospheric Science Journal ◽

10.2174/1874282300802010091 ◽

2008 ◽

Vol 2 (1) ◽

pp. 91-100 ◽

Cited By ~ 7

Author(s):

W. Dorn ◽

K. Dethloff ◽

A. Rinke ◽

M. Kurgansky

Keyword(s):

Climate Variability ◽

Sea Ice ◽

Arctic Ocean ◽

Interannual Variability ◽

Arctic Basin ◽

Ice Cover ◽

The Arctic ◽

Sea Ice Extent ◽

Internal Climate Variability ◽

Arctic Summer

By means of a 21-year simulation of a coupled regional pan-Arctic atmosphere-ocean-ice model for the 1980's and 1990's and comparison of the model results with SSM/I satellite-derived sea-ice concentrations, the patterns of maximum amplitude of interannual variability of the Arctic summer sea-ice cover are revealed. They are shown to concentrate beyond an area enclosed by an isopleth of barotropic planetary potential vorticity that marks the edge of the cyclonic rim current around the deep inner Arctic basin. It is argued that the propagation of the interannual variability signal farther into the inner Arctic basin is hindered by the dynamic isolation of upper Arctic Ocean and the high summer cloudiness usually appearing in the central Arctic. The thinning of the Arctic sea-ice cover in recent years is likely to be jointly responsible for its exceptionally strong decrease in summer 2007 when sea-ice decline was favored by anomalously high atmospheric pressure over the western Arctic Ocean, which can be regarded as a typical feature for years with low sea-ice extent. In addition, unusually low cloud cover appeared in summer 2007, which led to substantial warming of the upper ocean. It is hypothesized that the coincidence of several favorable factors for low sea-ice extent is responsible for this extreme event. Owing to the important role of internal climate variability in the recent decline of sea ice, a temporal return to previous conditions or stabilization at the current level can not be excluded just as further decline.

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Dipole Anomaly in the Winter Arctic Atmosphere and Its Association with Sea Ice Motion

Journal of Climate ◽

10.1175/jcli3619.1 ◽

2006 ◽

Vol 19 (2) ◽

pp. 210-225 ◽

Cited By ~ 159

Author(s):

Bingyi Wu ◽

Jia Wang ◽

John E. Walsh

Keyword(s):

Sea Ice ◽

Barents Sea ◽

Arctic Basin ◽

The Arctic ◽

Positive Phase ◽

Laptev Sea ◽

Nordic Seas ◽

Beaufort Gyre ◽

Arctic Atmosphere ◽

The Laptev Sea

Abstract This paper identified an atmospheric circulation anomaly–dipole structure anomaly in the Arctic atmosphere and its relationship with winter sea ice motion, based on the International Arctic Buoy Program (IABP) dataset (1979–98) and datasets from the National Centers for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR) for the period 1960–2002. The dipole anomaly corresponds to the second-leading mode of EOF of monthly mean sea level pressure (SLP) north of 70°N during the winter season (October–March) and accounts for 13% of the variance. One of its two anomalous centers is stably occupied between the Kara Sea and Laptev Sea; the other is situated from the Canadian Archipelago through Greenland extending southeastward to the Nordic seas. The dipole anomaly differs from one described in other papers that can be attributed to an eastward shift of the center of action of the North Atlantic Oscillation. The finding shows that the dipole anomaly also differs from the “Barents Oscillation” revealed in a study by Skeie. Since the dipole anomaly shows a strong meridionality, it becomes an important mechanism to drive both anomalous sea ice exports out of the Arctic Basin and cold air outbreaks into the Barents Sea, the Nordic seas, and northern Europe. When the dipole anomaly remains in its positive phase, that is, negative SLP anomalies appear between the Kara Sea and the Laptev Sea with concurrent positive SLP over from the Canadian Archipelago extending southeastward to Greenland, there are large-scale changes in the intensity and character of sea ice transport in the Arctic basin. The significant changes include a weakening of the Beaufort gyre, an increase in sea ice export out of the Arctic basin through Fram Strait and the northern Barents Sea, and enhanced sea ice import from the Laptev Sea and the East Siberian Sea into the Arctic basin. Consequently, more sea ice appears in the Greenland and the Barents Seas during the positive phase of the dipole anomaly. During the negative phase of the dipole anomaly, SLP anomalies show an opposite scenario in the Arctic Ocean and its marginal seas when compared to the positive phase, with the center of negative SLP anomalies over the Nordic seas. Correspondingly, sea ice exports decrease from the Arctic basin flowing into the Nordic seas and the northern Barents Sea because of the strengthened Beaufort gyre. The finding indicates that influences of the dipole anomaly on winter sea ice motion are greater than that of the winter AO, particularly in the central Arctic basin and northward to Fram Strait, implying that effects of the dipole anomaly on sea ice export out of the Arctic basin become robust. The dipole anomaly is closely related to atmosphere–ice–ocean interactions that influence the Barents Sea sector.

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SURGE AND WAVE CONDITIONS UNDER WARMER ICE-FREE ARCTIC OCEAN

Coastal Engineering Proceedings ◽

10.9753/icce.v36v.waves.39 ◽

2020 ◽

pp. 39

Author(s):

Martin Mall ◽

Ryota Nakamura ◽

Tomoya Shibayama

Keyword(s):

Negative Impact ◽

Arctic Basin ◽

Coastal Communities ◽

The Arctic ◽

Climate Modelling ◽

Sea Ice Extent ◽

The Past ◽

Wide Range ◽

Global And Local ◽

Modelling Approach

In the past decade the fast changes within the Arctic basin have become more pronounced. The Arctic amplification has an extremely wide range of global and local implications. The latter has already caused negative impact to coastal communities along the Arctic coastline, where the decreasing annual sea ice extent leaves much of the coastal water open for potential high wave attacks for a longer period of time. The study aims to investigate the use of pseudo-climate modelling approach in the Arctic by looking at meteorology, surge and waves.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/SjVaZRnFva8

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Information on the early Holocene climate constrains the summer sea ice projections for the 21st century

Climate of the Past ◽

10.5194/cp-3-683-2007 ◽

2007 ◽

Vol 3 (4) ◽

pp. 683-692 ◽

Cited By ~ 31

Author(s):

H. Goosse ◽

E. Driesschaert ◽

T. Fichefet ◽

M.-F. Loutre

Keyword(s):

Sea Ice ◽

21St Century ◽

Climate Model ◽

Arctic Basin ◽

Standard Test ◽

Early Holocene ◽

The Arctic ◽

Moderate Increase ◽

Sea Ice Extent ◽

Proxy Records

Abstract. The summer sea ice extent strongly decreased in the Arctic over the last decades. This decline is very likely to continue in the future but uncertainty of projections is very large. An ensemble of experiments with the climate model LOVECLIM using 5 different parameter sets has been performed to show that summer sea ice changes during the early Holocene (8 kyr BP) and the 21st century are strongly linked, allowing for the reduction of this uncertainty. Using the limited number of records presently available for the early Holocene, simulations presenting very large changes over the 21st century could reasonably be rejected. On the other hand, simulations displaying low to moderate changes during the second half of the 20th century (and also over the 21st century) are not consistent with recent observations. Using this very complementary information based on observations during both the early Holocene and the last decades, the most realistic projection with LOVECLIM indicates a nearly disappearance of the sea ice in summer at the end of the 21st century for a moderate increase in atmospheric greenhouse gas concentrations. Our results thus strongly indicate that additional proxy records of the early Holocene sea ice changes, in particular in the central Arctic Basin, would help to improve our projections of summer sea ice evolution and that the simulation at 8 kyr BP should be considered as a standard test for models aiming at simulating those future summer sea ice changes in the Arctic.

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Sea ice inertial oscillation magnitudes in the Arctic basin

The Cryosphere Discussions ◽

10.5194/tcd-6-2179-2012 ◽

2012 ◽

Vol 6 (3) ◽

pp. 2179-2220

Author(s):

F. Gimbert ◽

D. Marsan ◽

J. Weiss ◽

N. C. Jourdain ◽

B. Barnier

Keyword(s):

Sea Ice ◽

Arctic Basin ◽

The Arctic ◽

Ice Thickness ◽

Inertial Oscillation ◽

Inertial Motion ◽

Inertial Oscillations ◽

Dimensional Parameter ◽

Sea Ice Extent ◽

Sea Ice Thickness

Abstract. An original method to quantify the amplitude of inertial motion of oceanic and ice drifters, through the introduction of a non-dimensional parameter M defined from a spectral analysis, is presented. A strong seasonal dependence of the magnitude of sea ice inertial oscillations is revealed, in agreement with the corresponding annual cycles of sea ice extent, concentration, thickness, advection velocity, and deformation rates. The spatial pattern of the magnitude of the sea ice inertial oscillations over the Arctic basin is also in agreement with the sea ice thickness and concentration patterns. This argues for a strong link between the magnitude of inertial motion on one hand, the dissipation of energy through mechanical processes, and the cohesiveness of the cover on the other hand. Finally, a significant pluri-annual evolution towards greater magnitudes of inertial oscillations in recent years, in both summer and winter, is reported, thus concomitant with reduced sea ice thickness, concentration and spatial extent.

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