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 Atmospheric influences on the anomalous 2016 Antarctic sea ice decay

2017 ◽  
Author(s):  
Elisabeth Schlosser ◽  
F. Alexander Haumann ◽  
Marilyn N. Raphael
Keyword(s):  
Sea Ice ◽  
Early Onset ◽  
Meridional Flow ◽  
Reanalysis Data ◽  
Rapid Decrease ◽  
Weddell Sea ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Atmospheric Flow ◽  
Antarctic Sea Ice

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 end of September, and was followed by a rapid decrease. The decline of the sea ice area (SIA) started even earlier, namely in July. The decay was particularly strong in November where Antarctic SIE exhibited a negative anomaly (compared to the 1979–2015 average) of approximately 2 Mio. km2, which, combined with reduced Arctic SIE, led to a distinct minimum in global SIE. ECMWF- Interim reanalysis data were used to investigate possible atmospheric influences on the observed phenomena. The early onset of the melt and the rapid decrease in SIA and SIE were associated with atmospheric flow patterns related to a positive ZW3 index, i.e. synoptic situations leading to strong meridional flow. Particularly, 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 feed-back effects, leading to the extraordinary low November SIE. In 2016, the monthly mean SAM index reached its second lowest November value since the beginning of the satellite observations. SIE decrease was preconditioned by SIA decrease. 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 Spatio-temporal variability and decadal trends of snowmelt processes on Antarctic sea ice observed by satellite scatterometers

2019 ◽  
Author(s):  
Stefanie Arndt ◽  
Christian Haas
Keyword(s):  
Time Series ◽  
Sea Ice ◽  
Weddell Sea ◽  
Passive Microwave ◽  
The Arctic ◽  
Signal Frequency ◽  
Onset Date ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice ◽  
Perennial Ice

Abstract. The timing and intensity of snowmelt processes on sea ice are key drivers determining the seasonal sea-ice energy and mass budgets. In the Arctic, satellite passive microwave and radar observations have revealed a trend towards an earlier snowmelt onset during the last decades, which is an important aspect of Arctic amplification and sea ice decline. Around Antarctica, snowmelt on perennial ice is weak and very different than in the Arctic, with most snow surviving the summer. Here we compile time series of snowmelt-onset dates on seasonal and perennial Antarctic sea ice from 1992 to 2014/15 using active microwave observations from European Remote Sensing Satellite (ERS-1/2), Quick Scatterometer (QSCAT) and Advanced Scatterometer (ASCAT) radar scatterometers. We define two snowmelt transition stages: A weak backscatter rise indicating the initial warming and metamorphism of the snowpack (pre-melt), followed by a rapid backscatter rise indicating the onset of thaw-freeze cycles (snowmelt). Results show large interannual variability with an average pre-melt onset date of 29 November and melt onset of 10 December, respectively, on perennial ice, without any significant trends over the study period, consistent with the small trends of Antarctic sea ice extent. There was a latitudinal gradient from early snowmelt onsets in mid-November in the northern Weddell Sea to late (end-December) or even absent snowmelt conditions in the southern Weddell Sea. We show that QSCAT Ku-band (13.4 GHz signal frequency) derived pre-melt and snowmelt onset dates are earlier by 25 and 11 days, respectively, than ERS and ASCAT C-band (5.6 GHz) derived dates. This offset has been considered when constructing the time series. Snowmelt onset dates from passive microwave observations (37 GHz) are later by 13 and 5 days than those from the scatterometers, respectively. Based on these characteristic differences between melt onset dates observed by different microwave wavelengths, we developed a conceptual model which illustrates how the evolution of seasonal snow temperature profiles affects different microwave bands with different penetration depths. These suggest that future multi-frequency active/passive microwave satellite missions could be used to resolve melt processes throughout the vertical snow column.

scholarly journals Unraveling driving forces explaining significant reduction in satellite-inferred Arctic surface albedo since the 1980s

2019 ◽  
Vol 116 (48) ◽  
pp. 23947-23953 ◽  
Author(s):  
Rudong Zhang ◽  
Hailong Wang ◽  
Qiang Fu ◽  
Philip J. Rasch ◽  
Xuanji Wang
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Surface Albedo ◽  
Driving Forces ◽  
Surface Air Temperature ◽  
Reanalysis Data ◽  
The Arctic ◽  
Data Sets ◽  
Sea Ice Extent ◽  
Snow Cover Fraction

The Arctic has warmed significantly since the early 1980s and much of this warming can be attributed to the surface albedo feedback. In this study, satellite observations reveal a 1.25 to 1.51% per decade absolute reduction in the Arctic mean surface albedo in spring and summer during 1982 to 2014. Results from a global model and reanalysis data are used to unravel the causes of this albedo reduction. We find that reductions of terrestrial snow cover, snow cover fraction over sea ice, and sea ice extent appear to contribute equally to the Arctic albedo decline. We show that the decrease in snow cover fraction is primarily driven by the increase in surface air temperature, followed by declining snowfall. Although the total precipitation has increased as the Arctic warms, Arctic snowfall is reduced substantially in all analyzed data sets. Light-absorbing soot in snow has been decreasing in past decades over the Arctic, indicating that soot heating has not been the driver of changes in the Arctic snow cover, ice cover, and surface albedo since the 1980s.

scholarly journals Uncertainties in Arctic Sea Ice Thickness Associated with Different Atmospheric Reanalysis Datasets Using the CICE5 Model

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 361
Author(s):  
Su-Bong Lee ◽  
Baek-Min Kim ◽  
Jinro Ukita ◽  
Joong-Bae Ahn
Keyword(s):  
Sea Ice ◽  
Arctic Region ◽  
Reanalysis Data ◽  
Arctic Sea Ice ◽  
Heat Fluxes ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Sea Ice Extent ◽  
Ice Volume ◽  
Arctic Sea

Reanalysis data are known to have relatively large uncertainties in the polar region than at lower latitudes. In this study, we used a single sea-ice model (Los Alamos’ CICE5) and three sets of reanalysis data to quantify the sensitivities of simulated Arctic sea ice area and volume to perturbed atmospheric forcings. The simulated sea ice area and thickness thus volume were clearly sensitive to the selection of atmospheric reanalysis data. Among the forcing variables, changes in radiative and sensible/latent heat fluxes caused significant amounts of sensitivities. Differences in sea-ice concentration and thickness were primarily caused by differences in downward shortwave and longwave radiations. 2-m air temperature also has a significant influence on year-to-year variability of the sea ice volume. Differences in precipitation affected the sea ice volume by causing changes in the insulation effect of snow-cover on sea ice. The diversity of sea ice extent and thickness responses due to uncertainties in atmospheric variables highlights the need to carefully evaluate reanalysis data over the Arctic region.

scholarly journals Dynamic and Thermodynamic Impacts of the Winter Arctic Oscillation on Summer Sea Ice Extent

2018 ◽  
Vol 31 (4) ◽  
pp. 1483-1497 ◽  
Author(s):  
Hyo-Seok Park ◽  
Andrew L. Stewart ◽  
Jun-Hyeok Son
Keyword(s):  
Sea Ice ◽  
Radiative Forcing ◽  
Arctic Oscillation ◽  
Reanalysis Data ◽  
Heat Fluxes ◽  
The Arctic ◽  
Ice Thickness ◽  
Sea Ice Extent ◽  
The Pacific ◽  
Basin Scale

Arctic summer sea ice extent exhibits substantial interannual variability, as is highlighted by the remarkable recovery in sea ice extent in 2013 following the record minimum in the summer of 2012. Here, the mechanism via which Arctic Oscillation (AO)-induced ice thickness changes impact summer sea ice is explored, using observations and reanalysis data. A positive AO weakens the basin-scale anticyclonic sea ice drift and decreases the winter ice thickness by 15 and 10 cm in the Eurasian and the Pacific sectors of the Arctic, respectively. Three reanalysis datasets show that the upward surface heat fluxes are reduced over wide areas of the Arctic, suppressing the ice growth during the positive AO winters. The winter dynamic and thermodynamic thinning preconditions the ice for enhanced radiative forcing via the ice–albedo feedback in late spring–summer, leading to an additional 10 cm of thinning over the Pacific sector of the Arctic. Because of these winter AO-induced dynamic and thermodynamics effects, the winter AO explains about 22% ( r = −0.48) of the interannual variance of September sea ice extent from 1980 to 2015.

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 A record of Antarctic sea ice extent in the Southern Indian Ocean for the past 300 yr and its relationship with global mean temperature

2013 ◽  
Vol 7 (4) ◽  
pp. 3611-3625 ◽  
Author(s):  
C. Xiao ◽  
R. Li ◽  
S. B. Sneed ◽  
T. Dou ◽  
I. Allison
Keyword(s):  
Indian Ocean ◽  
Sea Ice ◽  
Temperature Change ◽  
Ice Core ◽  
Southern Annular Mode ◽  
Ice Age ◽  
Southern Indian Ocean ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice

Abstract. The differing response of ice extent in the Arctic and Antarctic to global average temperature change, over approximately the last three decades, highlights the importance of reconstructing long-term sea ice history. Here, using high-resolution ice core records of methanesulfonate (MS−) from the East Antarctic Ice Sheet in Princess Elizabeth Land, we reconstruct southern Indian Ocean sea ice extent (SIE) for the sector 70° E–100° E for the period 1708–2000 A.D. Annual MS− concentration positively correlates in this sector with satellite-derived SIE for the period 1973–2000 (P < 0.05). The 293 yr MS− record of proxy SIE shows multi-decadal variations, with large decreases occurring in two warm intervals during the Little Ice Age, and during the 1940s. However, after the 1980s there is a change in phase between Antarctic SIE and global temperature change, with both increasing. This paradox is probably attributable to the strong anomaly in the Southern Annular Mode (SAM) in the recent three decades.

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.

Features of changes in the sea ice and snow cover extents associated with temperature changes in the Northern and Southern Hemispheres in recent decades.

2021 ◽  
Author(s):  
Maria Parfenova ◽  
Igor I. Mokhov
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Snow Cover ◽  
Reanalysis Data ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice ◽  
Arctic Sea ◽  
Northern And Southern Hemispheres

&lt;p&gt;Quantitative estimates of the relationship between the interannual variability of Antarctic and Arctic sea ice and changes in the surface temperature in the Northern and Southern Hemispheres using satellitedata, observational data and reanalysis data for the last four decades (1980-2019) are obtained. The previously noted general increase in the Antarctic sea ice extent (up to 2016) (according to satellite data available only since the late 1970s), happening simultaneously with global warming and rapid decrease in the Arctic sea ice extent, is associated with the regional manifestation of natural climate fluctuations with periods of up to several decades. The results of correlation and crosswavelet analysis indicate significant coherence and negative correlation of hemispheric surface temperature with not only Arctic,but also Antarctic sea ice extent in recent decades.&lt;/p&gt;&lt;p&gt;Seasonal and regional peculiarities of snow cover sensitivity to temperature regime changes in the Northern Hemisphere are noted with an assessment of changes in recent decades. Peculiarities of snow cover variability in Eurasia and North America are presented. In particular, the peculiarities of changes in snow cover during the autumn seasons are noted.&lt;/p&gt;

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