scholarly journals A statistical definition of the Antarctic marginal ice zone

2021 ◽  
Author(s):  
Marcello Vichi
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
The Arctic ◽  
Spatial And Temporal Variability ◽  
Transitional Region ◽  
Climate Data ◽  
Good Correspondence ◽  
Marginal Ice Zone ◽  
Definition Of ◽  
The Antarctic

Abstract. The marginal ice zone (MIZ) is a transitional region between the open ocean and pack ice. This region is circumpolar in the Antarctic, with different sea ice types depending on the season and the sector of the Southern Ocean. The MIZ extent have traditionally been inferred from satellite-derived sea-ice concentration (SIC, one of the essential climate variables), using the 15–80 % range as indicative of sea ice with MIZ characteristics. This proxy has been proven effective in the Arctic, where there is a good correspondence between sea-ice type and sea-ice cover. It is less reliable in the Southern Ocean, where sea-ice type is less linked to the concentration value, since wave penetration and free drift conditions have been reported with 100 % cover. I propose an alternative definition of the MIZ that is based on statistical properties of the SIC and its spatial and temporal variability. The indicator is derived from the standard deviation of daily SIC anomalies, which is often employed in the climate sciences. The use of a monthly climatological mean as the baseline allows to capture changes due to both the seasonal advancement/retreat and the local weather-driven variability typical of less consolidated sea-ice conditions. This method has been tested on the available climate data records to derive maps of the MIZ distribution over the year. It reconciles the discordant seasonal extent estimates using the SIC threshold, which is now independent of the used algorithm. This indicator also allows to derive the climatological probability of exceeding a certain threshold of SIC variability, which can be used for ship navigation, design of observational networks and for testing the skills of sea-ice models in forecasting or climate mode.

scholarly journals Changes of the Arctic marginal ice zone during the satellite era

2020 ◽  
Vol 14 (6) ◽  
pp. 1971-1984 ◽  
Author(s):  
Rebecca J. Rolph ◽  
Daniel L. Feltham ◽  
David Schröder
Keyword(s):  
Sea Ice ◽  
Arctic Sea Ice ◽  
Satellite Observations ◽  
The Arctic ◽  
Upper And Lower Bounds ◽  
Sea Ice Concentration ◽  
Sea Ice Extent ◽  
Ice Concentration ◽  
Marginal Ice Zone ◽  
Definition Of

Abstract. Many studies have shown a decrease in Arctic sea ice extent. It does not logically follow, however, that the extent of the marginal ice zone (MIZ), here defined as the area of the ocean with ice concentrations from 15 % to 80 %, is also changing. Changes in the MIZ extent has implications for the level of atmospheric and ocean heat and gas exchange in the area of partially ice-covered ocean and for the extent of habitat for organisms that rely on the MIZ, from primary producers like sea ice algae to seals and birds. Here, we present, for the first time, an analysis of satellite observations of pan-Arctic averaged MIZ extent. We find no trend in the MIZ extent over the last 40 years from observations. Our results indicate that the constancy of the MIZ extent is the result of an observed increase in width of the MIZ being compensated for by a decrease in the perimeter of the MIZ as it moves further north. We present simulations from a coupled sea ice–ocean mixed layer model using a prognostic floe size distribution, which we find is consistent with, but poorly constrained by, existing satellite observations of pan-Arctic MIZ extent. We provide seasonal upper and lower bounds on MIZ extent based on the four satellite-derived sea ice concentration datasets used. We find a large and significant increase (>50 %) in the August and September MIZ fraction (MIZ extent divided by sea ice extent) for the Bootstrap and OSI-450 observational datasets, which can be attributed to the reduction in total sea ice extent. Given the results of this study, we suggest that references to “rapid changes” in the MIZ should remain cautious and provide a specific and clear definition of both the MIZ itself and also the property of the MIZ that is changing.

Evaluation of the numerical wave model (WaveWatch III) for wave simulation in the Antarctic marginal ice zone

2020 ◽  
Author(s):  
Marzieh H. Derkani ◽  
Katrin Hessner ◽  
Stefan Zieger ◽  
Filippo Nelli ◽  
Alberto Alberello ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Southern Hemisphere ◽  
Global Climate ◽  
Wave Model ◽  
Open Ocean ◽  
Wavewatch Iii ◽  
Marginal Ice Zone ◽  
The Antarctic ◽  
The Impact

<p>The Southern Ocean is the birthplace of the fiercest waves on the Earth, which play a fundamental role in global climate by regulating momentum, heat and gas exchanges between the atmosphere and ocean. At high latitudes, waves interact with Antarctic sea ice, another crucial player of the Earth's climate system, modulating its expansion in the winter and its retreat in summer and hence affecting the global albedo. Despite the impact of waves on climate, global wave models are considerably biased in the Southern Hemisphere, due to the scarcity of observations in these remote waters. This is exacerbated in the marginal ice zone, the region of ice-covered water between the compact ice or land and the open ocean, where surface waves, upper ocean and atmosphere interact with sea ice but the dominant physics are still largely unknown. To improve our understanding of physical processes in Southern Ocean and model capabilities, the Antarctic Circumnavigation Expedition (ACE) sailed these waters from December 2016 to March 2017 to acquire wave data (among other climate variables) both in the open ocean and Antarctic marginal ice zone. Observations were gathered using a radar-based wave and surface current monitoring system (WaMoS-II) built on board of the research icebreaker Akademik Tryoshnikov. Here, we discuss how these observations underpin the set up, calibration and validation of the WaveWatch III wave model over a domain covering the entire Southern Hemisphere, therefore spanning from tropical waters to the edge of sea ice (open waters only). The calibrated model will then be used to carry out a thorough assessment of different sea ice modules, to evaluate accuracy of predictions in the marginal ice zone. Test cases of waves-in-ice recorded during the Antarctic Circumnavigation Expeditions will be discussed in details.</p>

Impact of ice sheet – ocean interactions on the Southern Ocean using fully coupled models over a circumpolar domain

2021 ◽  
Author(s):  
Charles Pelletier ◽  
Lars Zipf ◽  
Konstanze Haubner ◽  
Deborah Verfaillie ◽  
Hugues Goosse ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ice Sheet ◽  
The Arctic ◽  
Surface Cooling ◽  
Coupled Models ◽  
Sea Ice Extent ◽  
Antarctic Ice Sheet ◽  
Antarctic Sea Ice ◽  
The Antarctic

<p>From at least 1979 up until 2016, the surface of the Southern Ocean cooled down, leading to a small Antarctic sea ice extent increase, which is in stark contrast with the Arctic Ocean. The attribution of the origin of these robust observations is still very uncertain. Among other phenomena, the direct, two-way interactions between the Southern Ocean and the Antarctic ice sheet, through basal melting of its numerous and large ice-shelf cavities, have been suggested as a potentially important contributor of this cooling. In order to address this question, we perform multidecadal coupled ice sheet – ocean numerical simulations relying on f.ETISh-v1.7 and NEMO3.6-LIM3 for simulating the Antarctic ice sheet and Southern Ocean (including sea ice), respectively. This presentation is twofold. First, we present the technical aspects of the coupling infrastructure (e.g. workflow and exchanged information in between models). Second, we investigate the ice sheet – ocean feedbacks on the Southern Ocean, their interactions, and the roles of the related physical mechanisms on the ocean surface cooling.</p>

scholarly journals Inter-annual variations observed in spring and summer Antarctic sea ice extent in recent decade

MAUSAM ◽  
2021 ◽  
Vol 62 (4) ◽  
pp. 633-640
Author(s):  
SANDIP R.OZA ◽  
R.K.K. SINGH ◽  
ABHINAV SRIVASTAVA ◽  
MIHIR K.DASH ◽  
I.M.L. DAS ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Large Scale ◽  
Ross Sea ◽  
Ice Cover ◽  
Weddell Sea ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice ◽  
The Antarctic

The growth and decay of sea ice are complex processes and have important feedback onto the oceanic and atmospheric circulation. In the Antarctic, sea ice variability significantly affects the primary productivity in the Southern Ocean and thereby negatively influences the performance and survival of species in polar ecosystem. In present days, the awareness on the sea ice variability in the Antarctic is not as matured as it is for the Arctic region. The present paper focuses on the inter-annual trends (1999-2009) observed in the monthly fractional sea ice cover in the Antarctic at 1 × 1 degree level, for the November and February months, derived from QuikSCAT scatterometer data. OSCAT scatterometer data from India’s Oceansat-2 satellite were used to asses the sea ice extent (SIE) observed in the month of November 2009 and February 2010 and its deviation from climatic maximum (1979-2002) sea ice extent (CMSIE). Large differences were observed between SIE and CMSIE, however, trend results show that it is due to the high inter-annual variability in sea ice cover. Spatial distribution of trends show the existence of positive and negative trends in the parts of Western Pacific Ocean, Ross Sea, Amundsen and Bellingshausen Seas (ABS), Weddell Sea and Indian ocean sector of southern ocean. Sea ice trends are compared with long-term SST trends (1982-2009) observed in the austral summer month of February. Large-scale cooling trend observed around Ross Sea and warming trend in ABS sector are the distinct outcome of the study.

scholarly journals Extreme Warming in the Kara Sea and Barents Sea during the Winter Period 2000–16

2017 ◽  
Vol 30 (22) ◽  
pp. 8913-8927 ◽  
Author(s):  
Svenja H. E. Kohnemann ◽  
Günther Heinemann ◽  
David H. Bromwich ◽  
Oliver Gutjahr
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Barents Sea ◽  
Kara Sea ◽  
The Arctic ◽  
Winter Period ◽  
Limited Area ◽  
Spatial And Temporal Variability ◽  
Large Variability ◽  
Air Temperatures

The regional climate model COSMO in Climate Limited-Area Mode (COSMO-CLM or CCLM) is used with a high resolution of 15 km for the entire Arctic for all winters 2002/03–2014/15. The simulations show a high spatial and temporal variability of the recent 2-m air temperature increase in the Arctic. The maximum warming occurs north of Novaya Zemlya in the Kara Sea and Barents Sea between March 2003 and 2012 and is responsible for up to a 20°C increase. Land-based observations confirm the increase but do not cover the maximum regions that are located over the ocean and sea ice. Also, the 30-km version of the Arctic System Reanalysis (ASR) is used to verify the CCLM for the overlapping time period 2002/03–2011/12. The differences between CCLM and ASR 2-m air temperatures vary slightly within 1°C for the ocean and sea ice area. Thus, ASR captures the extreme warming as well. The monthly 2-m air temperatures of observations and ERA-Interim data show a large variability for the winters 1979–2016. Nevertheless, the air temperature rise since the beginning of the twenty-first century is up to 8 times higher than in the decades before. The sea ice decrease is identified as the likely reason for the warming. The vertical temperature profiles show that the warming has a maximum near the surface, but a 0.5°C yr−1 increase is found up to 2 km. CCLM, ASR, and also the coarser resolved ERA-Interim data show that February and March are the months with the highest 2-m air temperature increases, averaged over the ocean and sea ice area north of 70°N; for CCLM the warming amounts to an average of almost 5°C for 2002/03–2011/12.

scholarly journals Sea ice drift in the Southern Ocean: Regional patterns, variability, and trends

Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
Ron Kwok ◽  
Shirley S. Pang ◽  
Sahra Kacimi
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Sea Level ◽  
Ice Cover ◽  
The Arctic ◽  
Positive Trend ◽  
Amundsen Sea ◽  
Regional Patterns ◽  
Ice Drift ◽  
Sea Ice Drift

Understanding long-term changes in large-scale sea ice drift in the Southern Ocean is of considerable interest given its contribution to ice extent, to ice production in open waters, with associated dense water formation and heat flux to the atmosphere, and thus to the climate system. In this paper, we examine the trends and variability of this ice drift in a 34-year record (1982–2015) derived from satellite observations. Uncertainties in drift (~3 to 4 km day–1) were assessed with higher resolution observations. In a linear model, drift speeds were ~1.4% of the geostrophic wind from reanalyzed sea-level pressure, nearly 50% higher than that of the Arctic. This result suggests an ice cover in the Southern Ocean that is thinner, weaker, and less compact. Geostrophic winds explained all but ~40% of the variance in ice drift. Three spatially distinct drift patterns were shown to be controlled by the location and depth of atmospheric lows centered over the Amundsen, Riiser-Larsen, and Davis seas. Positively correlated changes in sea-level pressures at the three centers (up to 0.64) suggest correlated changes in the wind-driven drift patterns. Seasonal trends in ice edge are linked to trends in meridional winds and also to on-ice/off-ice trends in zonal winds, due to zonal asymmetry of the Antarctic ice cover. Sea ice area export at flux gates that parallel the 1000-m isobath were extended to cover the 34-year record. Interannual variability in ice export in the Ross and Weddell seas linked to the depth and location of the Amundsen Sea and Riiser-Larsen Sea lows to their east. Compared to shorter records, where there was a significant positive trend in Ross Sea ice area flux, the longer 34-year trends of outflow from both seas are now statistically insignificant.

Last Glacial Maximum Antarctic sea ice linked with global mean ocean temperature: evidence from PMIP3, PMIP4 and MIROC-4m simulations

2021 ◽  
Author(s):  
Tristan Vadsaria ◽  
Sam Sherriff-Tadano ◽  
Ayako Abe-Ouchi ◽  
Takashi Obase ◽  
Wing-Le Chan ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Last Glacial Maximum ◽  
Ocean Circulation ◽  
Glacial Maximum ◽  
Ocean Temperature ◽  
Sea Ice Extent ◽  
Last Glacial ◽  
Antarctic Sea Ice ◽  
The Antarctic

<p>Southern Ocean sea ice and oceanic fronts are known to play an important role on the climate system, carbon cycles, bottom ocean circulation, and Antarctic ice sheet. However, many models of the previous Past-climate Model Intercomparison Project (PMIP) underestimated sea-ice extent (SIE) for the Last Glacial Maximum (LGM)(Roche et al., 2012; Marzocchi and Jensen, 2017), mainly because of surface bias (Flato et al., 2013) that may have an impact on mean ocean temperature (MOT). Indeed, recent studies further suggest an important link between Southern Ocean sea ice and mean ocean temperature (Ferrari et al., 2014; Bereiter et al., 2018 among others). Misrepresent the Antarctic sea-ice extent could highly impact deep ocean circulation, the heat transport and thus the MOT. In this study, we will stress the relationship between the distribution of Antarctic sea-ice extent and the MOT through the analysis of the PMIP3 and PMIP4 exercise and by using a set of MIROC models. To date, the latest version of MIROC improve its representation of the LGM Antarctic sea-ice extent, affecting the deep circulation and the MOT distribution (Sherriff-Tadano et al., under review).</p><p>Our results show that available PMIP4 models have an overall improvement in term of LGM sea-ice extent compared to PMIP3, associated to colder deep and bottom ocean temperature. Focusing on MIROC (4m) models, we show that models accounting for Southern Ocean sea-surface temperature (SST) bias correction reproduce an Antarctic sea-ice extent, 2D-distribution, and seasonal amplitude in good agreement with proxy-based data. Finally, using PMIP-MIROC analyze, we show that it exists a relationship between the maximum SIE and the MOT, modulated by the Antarctic intermediate and bottom waters.</p>

2. The physical environment

2021 ◽  
pp. 14-38
Author(s):  
Klaus Dodds ◽  
Jamie Woodward
Keyword(s):  
Sea Ice ◽  
Physical Environment ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Far North ◽  
Sea Ice Decline ◽  
Antarctic Continent ◽  
Polar Opposite ◽  
The Antarctic

‘The physical environment’ describes the Arctic as the polar opposite of the Antarctic continent as it is an ocean semi-enclosed by land. The rocks of the Arctic record key periods in Earth history. The Arctic environment has had an interesting path of evolution. Why is the Arctic cold today? The polar latitudes actually receive less solar energy than the rest of the Earth's surface. What is the key role of sea ice in the Arctic climate system? How does sea ice decline impact upon the Arctic Ocean? The Greenland ice sheet, high latitude glaciers, and the importance of permafrost in the far north are also important topics related to the physical environment.

Decoding Hosing and Heating Effects on Global Temperature and Meridional Circulations in a Warming Climate

2018 ◽  
Vol 31 (23) ◽  
pp. 9605-9623 ◽  
Author(s):  
Qin Wen ◽  
Jie Yao ◽  
Kristofer Döös ◽  
Haijun Yang
Keyword(s):  
Global Warming ◽  
Southern Ocean ◽  
Sea Ice ◽  
Heat Transport ◽  
Global Temperature ◽  
The Arctic ◽  
Freshwater Flux ◽  
Ice Melting ◽  
Warming Climate ◽  
Flux Change

The global temperature changes under global warming result from two effects: one is the pure radiative heating effect caused by a change in greenhouse gases, and the other is the freshwater effect related to changes in precipitation, evaporation, and sea ice. The two effects are separated in a coupled climate model through sensitivity experiments in this study. It is indicated that freshwater change has a significant cooling effect that can mitigate the global surface warming by as much as ~30%. Two significant regional cooling centers occur: one in the subpolar Atlantic and one in the Southern Ocean. The subpolar Atlantic cooling, also known as the “warming hole,” is triggered by sea ice melting and the southward cold-water advection from the Arctic Ocean, and is sustained by the weakened Atlantic meridional overturning circulation. The Southern Ocean surface cooling is triggered by sea ice melting along the Antarctic and is maintained by the enhanced northward Ekman flow. In these two regions, the effect of freshwater flux change dominates over that of radiation flux change, controlling the sea surface temperature change in the warming climate. The freshwater flux change also results in the Bjerknes compensation, with the atmosphere heat transport change compensating the ocean heat transport change by about 80% during the transient stage of global warming. In terms of global temperature and Earth’s energy balance, the freshwater change plays a stabilizing role in a warming climate.

An Analysis on the Change of Ship Speed According to Ice Load Signal in Continuous Icebreaking and Ramming

2018 ◽  
Author(s):  
Se-Jin Ahn ◽  
Woo-Seong An ◽  
Tak-Kee Lee ◽  
Kyungsik Choi
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
The Arctic ◽  
Time Duration ◽  
Amundsen Sea ◽  
Ice Load ◽  
Research Activities ◽  
The Arctic Ocean ◽  
The Antarctic ◽  
Ship Speed

Recently, the research activities by domestic and overseas researchers using the Korean ice-breaking research vessel, ARAON have been actively conducted. The ARAON regularly operates for research activities in the Antarctic and the Arctic Ocean every year. She conducts many scientific and engineering tasks including ice load measurement, investigation of the properties of material strength for sea ice, and icebreaking performance test during her voyages. Such tests provide important data for studying icebreaker. Ice-breaking mode is determined by conditions of sea ice and ice field, and it is divided into ramming and continuous icebreaking. When the icebreaker meets thick ice or icebergs, the ramming is conducted. At that time, the ship speed is generally slower than that of the continuous icebreaking. The ARAON conducted icebreaking performance tests at the Amundsen Sea in Antarctica in 2012. Many strain data were measured in the ramming and the continuous icebreaking. This study was based on the strain gauge signals measured by the ARAON during the research voyage in 2012 in the Antarctic and 2010 in the Arctic. The signals measured from repetitive ramming under the heavy ice condition in 2012 in the Antarctic Ocean were classified into the five profiles. And the classified ice load signals were analyzed with a focus on raising time, half-decaying time and total time duration. Also, the signals measured from continuous icebreaking in 2010 in the Arctic Ocean were analyzed in the same way as the ramming data. Finally, the time histories of ice load signals were summarized from the viewpoint of speed change at the time of ice load, and two data sets were compared.

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