scholarly journals Recent observations of superimposed ice and snow ice on sea ice in the northwestern Weddell Sea

2021 ◽  
Vol 15 (9) ◽  
pp. 4165-4178
Author(s):  
Stefanie Arndt ◽  
Christian Haas ◽  
Hanno Meyer ◽  
Ilka Peeken ◽  
Thomas Krumpen
Keyword(s):  
Energy Balance ◽  
Sea Ice ◽  
Ice Core ◽  
Austral Summer ◽  
Reanalysis Data ◽  
Weddell Sea ◽  
Ice Thickness ◽  
Sea Ice Extent ◽  
Ice Melt ◽  
The North

Abstract. Recent low summer sea ice extent in the Weddell Sea raises questions about the contributions of dynamic and thermodynamic atmospheric and oceanic energy fluxes. The roles of snow, superimposed ice, and snow ice are particularly intriguing, as they are sensitive indicators of changes in atmospheric forcing and as they could trigger snow–albedo feedbacks that could accelerate ice melt. Here we present snow depth data and ice core observations of superimposed ice and snow ice collected in the northwestern Weddell Sea in late austral summer 2019, supplemented by airborne ice thickness measurements. Texture, salinity, and oxygen isotope analyses showed mean thicknesses of superimposed and snow ice of 0.11±0.11 and 0.22±0.22 m, respectively, or 3 % to 54 % of total ice thickness. Mean snow depths ranged between 0.46±0.29 m in the south to 0.05±0.06 m in the north, with mean and modal total ice thicknesses of 4.12±1.87 to 1.62±1.05 m and 3.9 to 0.9 m, respectively. These snow and ice properties are similar to results from previous studies, suggesting that the ice's summer surface energy balance and related seasonal transition of snow properties have changed little in past decades. This is supported by our additional analyses of the summer energy balance using atmospheric reanalysis data and by melt onset observations from satellite scatterometry showing few recent changes.

scholarly journals Recent observations of superimposed ice and snow ice on sea ice in the northwestern Weddell Sea

2021 ◽  
Author(s):  
Stefanie Arndt ◽  
Christian Haas ◽  
Hanno Meyer ◽  
Ilka Peeken ◽  
Thomas Krumpen
Keyword(s):  
Energy Balance ◽  
Sea Ice ◽  
Ice Core ◽  
Austral Summer ◽  
Reanalysis Data ◽  
Weddell Sea ◽  
Ice Thickness ◽  
Sea Ice Extent ◽  
Ice Melt ◽  
The North

Abstract. Recent low summer sea ice extent in the Weddell Sea raises questions about the contributions of dynamic and thermodynamic atmospheric and oceanic energy fluxes. The roles of snow, superimposed ice, and snow ice are particularly intriguing, as they are sensitive indicators for changes in atmospheric forcing, and as they could trigger snow-albedo feedbacks that could accelerate ice melt. Here we present snow depth data and ice core observations of superimposed ice and snow ice collected in the northwestern Weddell Sea in late austral summer of 2019, supplemented by airborne ice thickness measurements. Texture, salinity, and oxygen isotope analyses showed mean thicknesses of superimposed and snow ice of 0.11 ± 0.11 m and 0.22 ± 0.22 m, respectively, or 3 to 54 % of total ice thickness. Mean snow depths ranged between 0.46 ± 0.29 m in the south to 0.05 ± 0.06 m in the north, with mean and modal, total ice thicknesses between 4.12 ± 1.87 m to 1.62 ± 1.05 m, and 3.9 m to 0.9 m, respectively. These snow and ice properties are similar to results from previous studies, suggesting that the ice’s summer surface energy balance and related seasonal transition of snow properties have changed little in past decades. This is supported by our additional analyses of the summer energy balance using atmospheric reanalysis data, and melt onset observations from satellite scatterometry showing little recent changes.

scholarly journals ICESat observations of seasonal and interannual variations of sea-ice freeboard and estimated thickness in the Weddell Sea, Antarctica (2003–2009)

2011 ◽  
Vol 52 (57) ◽  
pp. 43-51 ◽  
Author(s):  
Donghui Yi ◽  
H. Jay Zwally ◽  
John W. Robbins
Keyword(s):  
Sea Ice ◽  
Weddell Sea ◽  
Ice Thickness ◽  
Sea Ice Extent ◽  
Sea Ice Thickness ◽  
Earth Observing System ◽  
Pack Ice ◽  
Snow Water ◽  
The Mean ◽  
Seasonal And Interannual Variations

AbstractSea-ice freeboard heights for 17 ICESat campaign periods from 2003 to 2009 are derived from ICESat data. Freeboard is combined with snow depth from Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) data and nominal densities of snow, water and sea ice, to estimate sea-ice thickness. Sea-ice freeboard and thickness distributions show clear seasonal variations that reflect the yearly cycle of growth and decay of the Weddell Sea (Antarctica) pack ice. During October–November, sea ice grows to its seasonal maximum both in area and thickness; the mean freeboards are 0.33–0.41m and the mean thicknesses are 2.10–2.59 m. During February–March, thinner sea ice melts away and the sea-ice pack is mainly distributed in the west Weddell Sea; the mean freeboards are 0.35–0.46m and the mean thicknesses are 1.48–1.94 m. During May–June, the mean freeboards and thicknesses are 0.26–0.29m and 1.32–1.37 m, respectively. the 6 year trends in sea-ice extent and volume are (0.023±0.051)×106 km2 a–1 (0.45% a–1) and (0.007±0.092)×103 km3 a–1 (0.08% a–1); however, the large standard deviations indicate that these positive trends are not statistically significant.

scholarly journals A 120 000-year record of sea ice in the North Atlantic?

2019 ◽  
Vol 15 (6) ◽  
pp. 2031-2051 ◽  
Author(s):  
Niccolò Maffezzoli ◽  
Paul Vallelonga ◽  
Ross Edwards ◽  
Alfonso Saiz-Lopez ◽  
Clara Turetta ◽  
...  
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Ice Core ◽  
Arctic Sea Ice ◽  
First Year ◽  
Sea Ice Extent ◽  
Nordic Seas ◽  
The North ◽  
Arctic Sea ◽  
The North Atlantic

Abstract. Although it has been demonstrated that the speed and magnitude of the recent Arctic sea ice decline is unprecedented for the past 1450 years, few records are available to provide a paleoclimate context for Arctic sea ice extent. Bromine enrichment in ice cores has been suggested to indicate the extent of newly formed sea ice areas. Despite the similarities among sea ice indicators and ice core bromine enrichment records, uncertainties still exist regarding the quantitative linkages between bromine reactive chemistry and the first-year sea ice surfaces. Here we present a 120 000-year record of bromine enrichment from the RECAP (REnland ice CAP) ice core, coastal east Greenland, and interpret it as a record of first-year sea ice. We compare it to existing sea ice records from marine cores and tentatively reconstruct past sea ice conditions in the North Atlantic as far north as the Fram Strait (50–85∘ N). Our interpretation implies that during the last deglaciation, the transition from multi-year to first-year sea ice started at ∼17.5 ka, synchronously with sea ice reductions observed in the eastern Nordic Seas and with the increase in North Atlantic ocean temperature. First-year sea ice reached its maximum at 12.4–11.8 ka during the Younger Dryas, after which open-water conditions started to dominate, consistent with sea ice records from the eastern Nordic Seas and the North Icelandic shelf. Our results show that over the last 120 000 years, multi-year sea ice extent was greatest during Marine Isotope Stage (MIS) 2 and possibly during MIS 4, with more extended first-year sea ice during MIS 3 and MIS 5. Sea ice extent during the Holocene (MIS 1) has been less than at any time in the last 120 000 years.

scholarly journals Ice-Core Evidence For Weddell Sea Ice Extent During The Past 200 Years

1990 ◽  
Vol 14 ◽  
pp. 350
Author(s):  
R. Mulvaney ◽  
A.P. Reid ◽  
D A. Peel
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Antarctic Peninsula ◽  
Seasonal Cycle ◽  
Global Climate ◽  
Ice Core ◽  
Weddell Sea ◽  
Sea Ice Extent ◽  
Storm Activity ◽  
The Core

A continuous, detailed, 200-years record of the anionic species, chloride, nitrate and sulphate, has been measured on an ice core from Dolleman Island (70°35.2′ S, 60°55.5′ W), Antarctic Peninsula. The site lies on the east coast of the Peninsula, and the chemistry of the core is dominated by the changing pattern of sea-ice distribution and storm activity in the Wed dell Sea. Strong annual cycles in chloride and non sea salt sulphate reflect the dominance of the seasonal cycle in sea-ice distribution in the Weddell Sea, observed in time series derived from satellite imagery since the early 1970s. However, in the case of chloride there is also an exceptionally strong interannual variability, which in many parts of the core dominates the seasonal cycle. Secular variations in the sea-ice extent appear to have a strong influence on the climate of the region and may play a major role in determining how long-term climate change in the Antarctic Peninsula relates to global climate change. The paper examines documented evidence for sea-ice extent in the Weddell Sea sector, and evaluates the usefulness of ice-core data for reconstructing this parameter in the earlier period.

scholarly journals Sea-ice evaluation of NEMO-Nordic 1.0: a NEMO–LIM3.6-based ocean–sea-ice model setup for the North Sea and Baltic Sea

2017 ◽  
Vol 10 (8) ◽  
pp. 3105-3123 ◽  
Author(s):  
Per Pemberton ◽  
Ulrike Löptien ◽  
Robinson Hordoir ◽  
Anders Höglund ◽  
Semjon Schimanke ◽  
...  
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
North Sea ◽  
Thickness Distribution ◽  
Ice Thickness ◽  
The Baltic Sea ◽  
Sea Ice Extent ◽  
The North ◽  
The North Sea ◽  
The Baltic

Abstract. The Baltic Sea is a seasonally ice-covered marginal sea in northern Europe with intense wintertime ship traffic and a sensitive ecosystem. Understanding and modeling the evolution of the sea-ice pack is important for climate effect studies and forecasting purposes. Here we present and evaluate the sea-ice component of a new NEMO–LIM3.6-based ocean–sea-ice setup for the North Sea and Baltic Sea region (NEMO-Nordic). The setup includes a new depth-based fast-ice parametrization for the Baltic Sea. The evaluation focuses on long-term statistics, from a 45-year long hindcast, although short-term daily performance is also briefly evaluated. We show that NEMO-Nordic is well suited for simulating the mean sea-ice extent, concentration, and thickness as compared to the best available observational data set. The variability of the annual maximum Baltic Sea ice extent is well in line with the observations, but the 1961–2006 trend is underestimated. Capturing the correct ice thickness distribution is more challenging. Based on the simulated ice thickness distribution we estimate the undeformed and deformed ice thickness and concentration in the Baltic Sea, which compares reasonably well with observations.

scholarly journals A High-Resolution Anion Profile of an Ice Core From Dolleman Island, Antarctic Peninsula (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 204-205 ◽  
Author(s):  
Robert Mulvaney ◽  
David A. Peel
Keyword(s):  
High Resolution ◽  
Sea Ice ◽  
Antarctic Peninsula ◽  
Ice Core ◽  
Weddell Sea ◽  
Sea Salt ◽  
Sea Ice Extent ◽  
The Core ◽  
The Antarctic ◽  
Annual Flux

In January 1986, a 133 m ice core, with an estimated age at the bottom of 300-350 years, was collected (using an electromechanical drill) on Dolleman Island (70° 35.2′S, 60°55.5′ W; 398 ma.s.l.; 10 m temperature −16.75°C). The site lies on the east coast of the Antarctic Peninsula and has a continental-type climate dominated by perennial sea ice in the Weddell Sea. The core is being analysed for a range of chemical impurities, in order to assess their potential as indicators of past climate. High-resolution (10-15 samples a−1) continuous profiles of the anionic species Cl−1, NO3 − and SO4 2−, together with the cation Na+, have been measured on a section of the core from 26 to 71 m depth. The core has previously been dated between 0 and 32 m depth using the δ18O profile (Peel and others 1988). Lack of δ18O data for the section 32-71 m forced us to seek an alternative method of dating. Biogenic outgassing of sulphurous gases from the ocean and subsequent photochemical oxidation contribute an excess of sulphate over that derived from the marine aerosol. We show that excess sulphate, calculated as (concentrations in Eq. 1−1 and assuming that all measured Na+ is derived from sea salt), is highly seasonal in character, and annual horizons are well preserved over the whole of the core. This enabled us to determine the chronology to 71 m depth, and date the bottom of this section as 1844 ± 5 years. Cl− is derived mainly from sea salt. Its profile in the core is also seasonal in character, with peaks that tend to occur in late summer, reflecting the period of minimum sea-ice extent in the Weddell Sea, and therefore maximum source area for the uptake of sea salt. From instrumental meteorological records, Limbert (1974) showed that there were three extended periods of warm or cold weather in the Antarctic Peninsula between 1903 and 1944. During the two 4 year cold periods, when the summer break-up of sea ice in the Weddell Sea is likely to have been reduced, we found that the annual flux of Cl− to the Dolleman Island snow-pack was lower than the average. Conversely, the 3 year warm period showed a peak in the values of annual flux of Cl−. We therefore propose that Cl− can be used as a palaeoclimatic indicator for sea-ice extent. Extending our chloride data into the latter half of the nineteenth century (before the earliest continuous instrumental records for the Antarctic), we found three distinct peaks in the values of annual flux of Cl−. We suggest that the period 1850-60 was marked by a decrease in Weddell Sea ice extent (due perhaps to a warm period), followed by an extended period of increased sea ice. There were then two periods of much-reduced sea ice during (approximately) 1885-1890 and 1895-1900, with an intervening period of greatly increased ice coverage. These events are in good agreement with the warm and cold periods which Aristarain and others (1986) identified in the deuterium profile from James Ross Island.

scholarly journals Ice-Core Evidence For Weddell Sea Ice Extent During The Past 200 Years

1990 ◽  
Vol 14 ◽  
pp. 350-350
Author(s):  
R. Mulvaney ◽  
A.P. Reid ◽  
D A. Peel
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Antarctic Peninsula ◽  
Seasonal Cycle ◽  
Global Climate ◽  
Ice Core ◽  
Weddell Sea ◽  
Sea Ice Extent ◽  
Storm Activity ◽  
The Core

A continuous, detailed, 200-years record of the anionic species, chloride, nitrate and sulphate, has been measured on an ice core from Dolleman Island (70°35.2′ S, 60°55.5′ W), Antarctic Peninsula. The site lies on the east coast of the Peninsula, and the chemistry of the core is dominated by the changing pattern of sea-ice distribution and storm activity in the Wed dell Sea. Strong annual cycles in chloride and non sea salt sulphate reflect the dominance of the seasonal cycle in sea-ice distribution in the Weddell Sea, observed in time series derived from satellite imagery since the early 1970s. However, in the case of chloride there is also an exceptionally strong interannual variability, which in many parts of the core dominates the seasonal cycle.Secular variations in the sea-ice extent appear to have a strong influence on the climate of the region and may play a major role in determining how long-term climate change in the Antarctic Peninsula relates to global climate change. The paper examines documented evidence for sea-ice extent in the Weddell Sea sector, and evaluates the usefulness of ice-core data for reconstructing this parameter in the earlier period.

scholarly journals Atmospheric influences on the anomalous 2016 Antarctic sea ice decay

2018 ◽  
Vol 12 (3) ◽  
pp. 1103-1119 ◽  
Author(s):  
Elisabeth Schlosser ◽  
F. Alexander Haumann ◽  
Marilyn N. Raphael
Keyword(s):  
Sea Ice ◽  
Early Onset ◽  
Southern Annular Mode ◽  
Meridional Flow ◽  
Reanalysis Data ◽  
Rapid Decrease ◽  
Weddell Sea ◽  
The Arctic ◽  
Wave Number ◽  
Sea Ice Extent

Abstract. In contrast to the Arctic, where total sea ice extent (SIE) has been decreasing for the last three decades, Antarctic SIE has shown a small, but significant, increase during the same time period. However, in 2016, an unusually early onset of the melt season was observed; the maximum Antarctic SIE was already reached as early as August rather than the end of September, and was followed by a rapid decrease. The decay was particularly strong in November, when Antarctic SIE exhibited a negative anomaly (compared to the 1979–2015 average) of approximately 2 million km2. ECMWF Interim reanalysis data showed that the early onset of the melt and the rapid decrease in sea ice area (SIA) and SIE were associated with atmospheric flow patterns related to a positive zonal wave number three (ZW3) index, i.e., synoptic situations leading to strong meridional flow and anomalously strong southward heat advection in the regions of strongest sea ice decline. A persistently positive ZW3 index from May to August suggests that SIE decrease was preconditioned by SIA decrease. In particular, in the first third of November northerly flow conditions in the Weddell Sea and the Western Pacific triggered accelerated sea ice decay, which was continued in the following weeks due to positive feedback effects, leading to the unusually low November SIE. In 2016, the monthly mean Southern Annular Mode (SAM) index reached its second lowest November value since the beginning of the satellite observations. A better spatial and temporal coverage of reliable ice thickness data is needed to assess the change in ice mass rather than ice area.

scholarly journals Sea-ice evaluation of NEMO-Nordic 1.0: a NEMO–LIM3.6 based ocean–sea ice model setup for the North Sea and Baltic Sea

2017 ◽  
Author(s):  
Per Pemberton ◽  
Ulrike Löptien ◽  
Robinson Hordoir ◽  
Anders Höglund ◽  
Semjon Schimanke ◽  
...  
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
North Sea ◽  
Ice Thickness ◽  
The Baltic Sea ◽  
Sea Ice Extent ◽  
The North ◽  
The North Sea ◽  
The Baltic

Abstract. The Baltic Sea is a seasonally ice covered marginal sea in northern Europe with intense wintertime ship traffic and a sensitive ecosystem. Understanding and modeling the evolution of the sea-ice pack is important for climate effect studies and forecasting purposes. Here we present and evaluate the sea-ice component of a new NEMO–LIM3.6 based ocean–sea ice setup for the North Sea and Baltic Sea region. The setup includes a new depth-based fast ice parametrization for the Baltic Sea. The evaluation focuses on long-term statistics, from a 45-year long hindcast, although short-term daily performance is also briefly evaluated. Different sea-ice metrics such as sea-ice extent, concentration and thickness are compared to the best available observational dataset to identify model biases. Overall the model agrees well with the observations in terms of the long-term mean sea-ice extent and thickness. The variability of the annual maximum Baltic Sea ice extent is well in line with the observations but the 1961–2006 trend is underestimated. Based on the simulated ice thickness distribution we estimate the undeformed and deformed ice thickness and concentration in the Baltic Sea, which compares reasonably well with observations. We conclude that the new North Sea/Baltic Sea ocean–sea ice setup is well suited for further climate studies and sea ice forecasts.

scholarly journals A High-Resolution Anion Profile of an Ice Core From Dolleman Island, Antarctic Peninsula (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 204-205
Author(s):  
Robert Mulvaney ◽  
David A. Peel
Keyword(s):  
High Resolution ◽  
Sea Ice ◽  
Antarctic Peninsula ◽  
Ice Core ◽  
Weddell Sea ◽  
Sea Salt ◽  
Sea Ice Extent ◽  
The Core ◽  
The Antarctic ◽  
Annual Flux

In January 1986, a 133 m ice core, with an estimated age at the bottom of 300-350 years, was collected (using an electromechanical drill) on Dolleman Island (70° 35.2′S, 60°55.5′ W; 398 ma.s.l.; 10 m temperature −16.75°C). The site lies on the east coast of the Antarctic Peninsula and has a continental-type climate dominated by perennial sea ice in the Weddell Sea. The core is being analysed for a range of chemical impurities, in order to assess their potential as indicators of past climate.High-resolution (10-15 samples a−1) continuous profiles of the anionic species Cl−1, NO3− and SO42−, together with the cation Na+, have been measured on a section of the core from 26 to 71 m depth. The core has previously been dated between 0 and 32 m depth using the δ18O profile (Peel and others 1988). Lack of δ18O data for the section 32-71 m forced us to seek an alternative method of dating.Biogenic outgassing of sulphurous gases from the ocean and subsequent photochemical oxidation contribute an excess of sulphate over that derived from the marine aerosol. We show that excess sulphate, calculated as(concentrations in Eq. 1−1 and assuming that all measured Na+ is derived from sea salt), is highly seasonal in character, and annual horizons are well preserved over the whole of the core. This enabled us to determine the chronology to 71 m depth, and date the bottom of this section as 1844 ± 5 years.Cl− is derived mainly from sea salt. Its profile in the core is also seasonal in character, with peaks that tend to occur in late summer, reflecting the period of minimum sea-ice extent in the Weddell Sea, and therefore maximum source area for the uptake of sea salt. From instrumental meteorological records, Limbert (1974) showed that there were three extended periods of warm or cold weather in the Antarctic Peninsula between 1903 and 1944. During the two 4 year cold periods, when the summer break-up of sea ice in the Weddell Sea is likely to have been reduced, we found that the annual flux of Cl− to the Dolleman Island snow-pack was lower than the average. Conversely, the 3 year warm period showed a peak in the values of annual flux of Cl−. We therefore propose that Cl− can be used as a palaeoclimatic indicator for sea-ice extent.Extending our chloride data into the latter half of the nineteenth century (before the earliest continuous instrumental records for the Antarctic), we found three distinct peaks in the values of annual flux of Cl−. We suggest that the period 1850-60 was marked by a decrease in Weddell Sea ice extent (due perhaps to a warm period), followed by an extended period of increased sea ice. There were then two periods of much-reduced sea ice during (approximately) 1885-1890 and 1895-1900, with an intervening period of greatly increased ice coverage. These events are in good agreement with the warm and cold periods which Aristarain and others (1986) identified in the deuterium profile from James Ross Island.

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