Antarctic sea ice types from active and passive microwave remote sensing

Abstract. Polar sea ice is one of the Earth’s climate components that has been significantly affected by the recent trend of global warming. While the sea ice area in the Arctic has been decreasing at a rate of about 4 % per decade, the multi-year ice (MYI), also called perennial ice, is decreasing at a faster rate of 10 %–15 % per decade. On the other hand, the sea ice area in the Antarctic region was slowly increasing at a rate of about 1.5 % per decade until 2014 and since then it has fluctuated without a clear trend. However, no data about ice type areas are available from that region, particularly of MYI. Due to differences in physical and crystalline structural properties of sea ice and snow between the two polar regions, it has become difficult to identify ice types in the Antarctic. Until recently, no method has existed to monitor the distribution and temporal development of Antarctic ice types, particularly MYI throughout the freezing season and on decadal time scales. In this study, we have adapted a method for retrieving Arctic sea ice types and partial concentrations using microwave satellite observations to fit the Antarctic sea ice conditions. The first circumpolar, long-term time series of Antarctic sea ice types; MYI, first-year ice and young ice is being established, so far covering years 2013–2019. Qualitative comparison with synthetic aperture radar data, with charts of the development stage of the sea ice, and with Antarctic polynya distribution data show that the retrieved ice types, in particular the MYI, are reasonable. Although there are still some shortcomings, the new retrieval for the first time allows insight into the evolution and dynamics of Antarctic sea ice types. The current time series can in principle be extended backwards to start in the year 2002 and can be continued with current and future sensors.

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The Arctic and Antarctic Sea-Ice Area Index Records versus Measured and Modeled Temperature Data

Advances in Meteorology ◽

10.1155/2015/481834 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Nicola Scafetta ◽

Adriano Mazzarella

Keyword(s):

Sea Ice ◽

General Circulation ◽

General Circulation Models ◽

Arctic Sea Ice ◽

The Arctic ◽

Climate Indices ◽

Area Index ◽

Antarctic Sea Ice ◽

Arctic Sea ◽

The Antarctic

Here we study the Arctic and Antarctic sea-ice area records provided by the National Snow and Ice Data Center (NSIDC). These records reveal an opposite climatic behavior: since 1978 the Arctic sea-ice area index decreased, that is, the region has warmed, while the Antarctic sea-ice area index increased, that is, the region has cooled. During the last 7 years the Arctic sea-ice area has stabilized while the Antarctic sea-ice area has increased at a rate significantly higher than during the previous decades; that is, the sea-ice area of both regions has experienced a positive acceleration. This result is quite robust because it is confirmed by alternative temperature climate indices of the same regions. We also found that a significant 4-5-year natural oscillation characterizes the climate of these sea-ice polar areas. On the contrary, we found that the CMIP5 general circulation models have predicted significant warming in both polar sea regions and failed to reproduce the strong 4-5-year oscillation. Because the CMIP5 GCM simulations are inconsistent with the observations, we suggest that important natural mechanisms of climate change are missing in the models.

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Contrasting the Antarctic and Arctic Atmospheric Responses to Projected Sea Ice Loss in the Late Twenty-First Century

Journal of Climate ◽

10.1175/jcli-d-17-0666.1 ◽

2018 ◽

Vol 31 (16) ◽

pp. 6353-6370 ◽

Cited By ~ 14

Author(s):

Mark England ◽

Lorenzo Polvani ◽

Lantao Sun

Keyword(s):

Sea Ice ◽

Climate Model ◽

Arctic Sea Ice ◽

First Century ◽

The Arctic ◽

Minor Role ◽

Systems Model ◽

Antarctic Sea Ice ◽

Twenty First Century ◽

The Antarctic

Abstract Models project that Antarctic sea ice area will decline considerably by the end of this century, but the consequences remain largely unexplored. Here, the atmospheric response to future sea ice loss in the Antarctic is investigated, and contrasted to the Arctic case, using the Community Earth Systems Model (CESM) Whole Atmosphere Coupled Climate Model (WACCM). Time-slice model runs with historic sea ice concentrations are compared to runs with future concentrations, from the late twenty-first century, in each hemisphere separately. As for the Arctic, results indicate that Antarctic sea ice loss will act to shift the tropospheric jet equatorward, an internal negative feedback to the poleward shift associated with increased greenhouse gases. Also, the tropospheric response to Antarctic sea ice loss is found to be somewhat weaker, more vertically confined, and less seasonally varying than in the case of Arctic sea ice loss. The stratospheric response to Antarctic sea ice loss is relatively weak compared to the Arctic case, although it is here demonstrated that the latter is still small relative to internal variability. In contrast to the Arctic case, the response of the ozone layer is found to be positive (up to 5 Dobson units): interestingly, it is present in all seasons except austral spring. Finally, while the response of surface temperature and precipitation is limited to the southern high latitudes, it is nonetheless unable to impact the interior of the Antarctic continent, suggesting a minor role of sea ice loss on recent Antarctic temperature trends.

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A 40-y record reveals gradual Antarctic sea ice increases followed by decreases at rates far exceeding the rates seen in the Arctic

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1906556116 ◽

2019 ◽

Vol 116 (29) ◽

pp. 14414-14423 ◽

Cited By ~ 79

Author(s):

Claire L. Parkinson

Keyword(s):

Sea Ice ◽

Ice Cover ◽

Arctic Sea Ice ◽

The Arctic ◽

Antarctic Sea Ice ◽

Ice Coverage ◽

Yearly Average ◽

Precipitous Decline ◽

The One ◽

The Antarctic

Following over 3 decades of gradual but uneven increases in sea ice coverage, the yearly average Antarctic sea ice extents reached a record high of 12.8 × 106 km2 in 2014, followed by a decline so precipitous that they reached their lowest value in the 40-y 1979–2018 satellite multichannel passive-microwave record, 10.7 × 106 km2, in 2017. In contrast, it took the Arctic sea ice cover a full 3 decades to register a loss that great in yearly average ice extents. Still, when considering the 40-y record as a whole, the Antarctic sea ice continues to have a positive overall trend in yearly average ice extents, although at 11,300 ± 5,300 km2⋅y−1, this trend is only 50% of the trend for 1979–2014, before the precipitous decline. Four of the 5 sectors into which the Antarctic sea ice cover is divided all also have 40-y positive trends that are well reduced from their 2014–2017 values. The one anomalous sector in this regard, the Bellingshausen/Amundsen Seas, has a 40-y negative trend, with the yearly average ice extents decreasing overall in the first 3 decades, reaching a minimum in 2007, and exhibiting an overall upward trend since 2007 (i.e., reflecting a reversal in the opposite direction from the other 4 sectors and the Antarctic sea ice cover as a whole).

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New estimates of Arctic and Antarctic sea ice extent during September 1964 from recovered Nimbus I satellite imagery

The Cryosphere ◽

10.5194/tc-7-699-2013 ◽

2013 ◽

Vol 7 (2) ◽

pp. 699-705 ◽

Cited By ~ 38

Author(s):

W. N. Meier ◽

D. Gallaher ◽

G. G. Campbell

Keyword(s):

Sea Ice ◽

Satellite Imagery ◽

Arctic Sea Ice ◽

Passive Microwave ◽

The Arctic ◽

Sea Ice Extent ◽

Antarctic Sea Ice ◽

1960S And 1970S ◽

The 1960S ◽

The Antarctic

Abstract. Visible satellite imagery from the 1964 Nimbus I satellite has been recovered, digitized, and processed to estimate Arctic and Antarctic sea ice extent for September 1964. September is the month when the Arctic sea ice reaches its minimum annual extent and the Antarctic sea ice reaches its maximum. Images from a three-week period were manually analyzed to estimate the location of the ice edge and then composited to obtain a hemispheric estimate. Uncertainties were based on limitations in the image analysis and the variation of the ice cover over the three-week period. The 1964 Antarctic extent is higher than estimates from the 1979–present passive microwave record, but is in accord with previous indications of higher extents during the 1960s. The Arctic 1964 extent is near the 1979–2000 average from the passive microwave record, suggesting relatively stable summer extents during the 1960s and 1970s preceding the downward trend since 1979 and particularly the large decrease in the last decade. These early satellite data put the recently observed record into a longer-term context.

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Brief communication: Increasing shortwave absorption over the Arctic Ocean is not balanced by trends in the Antarctic

The Cryosphere ◽

10.5194/tc-11-2111-2017 ◽

2017 ◽

Vol 11 (5) ◽

pp. 2111-2116 ◽

Cited By ~ 3

Author(s):

Christian Katlein ◽

Stefan Hendricks ◽

Jeffrey Key

Keyword(s):

Sea Ice ◽

Cloud Cover ◽

Arctic Sea Ice ◽

Shortwave Radiation ◽

The Arctic ◽

Sea Ice Extent ◽

Antarctic Sea Ice ◽

Arctic Sea ◽

The Antarctic

Abstract. On the basis of a new, consistent, long-term observational satellite dataset we show that, despite the observed increase of sea ice extent in the Antarctic, absorption of solar shortwave radiation in the Southern Ocean poleward of 60° latitude is not decreasing. The observations hence show that the small increase in Antarctic sea ice extent does not compensate for the combined effect of retreating Arctic sea ice and changes in cloud cover, which both result in a total increase in solar shortwave energy deposited into the polar oceans.

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Comparing and contrasting the behaviour of Arctic and Antarctic sea ice over the 35 year period 1979-2013

Annals of Glaciology ◽

10.3189/2015aog69a909 ◽

2015 ◽

Vol 56 (69) ◽

pp. 18-28 ◽

Cited By ~ 168

Author(s):

Ian Simmonds

Keyword(s):

Sea Ice ◽

Coupled Model ◽

Arctic Sea Ice ◽

The Arctic ◽

Positive Trend ◽

Polar Regions ◽

Sea Ice Extent ◽

Antarctic Sea Ice ◽

Arctic Sea ◽

The Antarctic

AbstractWe examine the evolution of sea-ice extent (SIE) over both polar regions for 35 years from November 1978 to December 2013, as well as for the global total ice (Arctic plus Antarctic). Our examination confirms the ongoing loss of Arctic sea ice, and we find significant (p˂ 0.001) negative trends in all months, seasons and in the annual mean. The greatest rate of decrease occurs in September, and corresponds to a loss of 3 x 106 km2 over 35 years. The Antarctic shows positive trends in all seasons and for the annual mean (p˂0.01), with summer attaining a reduced significance (p˂0.10). Based on our longer record (which includes the remarkable year 2013) the positive Antarctic ice trends can no longer be considered ‘small’, and the positive trend in the annual mean of (15.29 ± 3.85) x 103 km2 a–1 is almost one-third of the magnitude of the Arctic annual mean decrease. The global annual mean SIE series exhibits a trend of (–35.29 ± 5.75) x 103 km2 a-1 (p<0.01). Finally we offer some thoughts as to why the SIE trends in the Coupled Model Intercomparison Phase 5 (CMIP5) simulations differ from the observed Antarctic increases.

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Sea Ice Trends in Climate Models Only Accurate in Runs with Biased Global Warming

Journal of Climate ◽

10.1175/jcli-d-16-0455.1 ◽

2017 ◽

Vol 30 (16) ◽

pp. 6265-6278 ◽

Cited By ~ 48

Author(s):

Erica Rosenblum ◽

Ian Eisenman

Keyword(s):

Global Warming ◽

Sea Ice ◽

Climate Models ◽

Arctic Sea Ice ◽

The Arctic ◽

Antarctic Sea Ice ◽

Arctic Sea ◽

Ice Retreat ◽

Sea Ice Retreat ◽

The Antarctic

Observations indicate that the Arctic sea ice cover is rapidly retreating while the Antarctic sea ice cover is steadily expanding. State-of-the-art climate models, by contrast, typically simulate a moderate decrease in both the Arctic and Antarctic sea ice covers. However, in each hemisphere there is a small subset of model simulations that have sea ice trends similar to the observations. Based on this, a number of recent studies have suggested that the models are consistent with the observations in each hemisphere when simulated internal climate variability is taken into account. Here sea ice changes during 1979–2013 are examined in simulations from the most recent Coupled Model Intercomparison Project (CMIP5) as well as the Community Earth System Model Large Ensemble (CESM-LE), drawing on previous work that found a close relationship in climate models between global-mean surface temperature and sea ice extent. All of the simulations with 1979–2013 Arctic sea ice retreat as fast as observations are found to have considerably more global warming than observations during this time period. Using two separate methods to estimate the sea ice retreat that would occur under the observed level of global warming in each simulation in both ensembles, it is found that simulated Arctic sea ice retreat as fast as observations would occur less than 1% of the time. This implies that the models are not consistent with the observations. In the Antarctic, simulated sea ice expansion as fast as observations is found to typically correspond with too little global warming, although these results are more equivocal. As a result, the simulations do not capture the observed asymmetry between Arctic and Antarctic sea ice trends. This suggests that the models may be getting the right sea ice trends for the wrong reasons in both polar regions.

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Remote sensing of multiyear ice in the Antarctic

10.5194/dach2022-284 ◽

2021 ◽

Author(s):

Christian Melsheimer ◽

Gunnar Spreen

Keyword(s):

Time Series ◽

Sea Ice ◽

Global Climate ◽

Ice Cover ◽

Cold Season ◽

Arctic Sea Ice ◽

Weddell Sea ◽

Detailed Knowledge ◽

The Antarctic ◽

Multiyear Ice

The changing sea ice cover of polar seas is of key importance for the exchange of heat and moisture between atmosphere and ocean and hence for weather and climate, and in addition, the sea ice and its long-term changes are &#160;an indicator for global change. &#160;In order to properly understand and model the evolution of the sea ice cover and its interaction with the global climate system, we need detailed knowledge about sea ice, i.e., not only its extent, but also, e.g., its thickness and its type. We can broadly distinguish a few different sea ice types that have different dynamic and thermodynamic properties, namely: young ice (YI, thin/smooth new ice), first-year ice (FYI, formed during one cold season), and multiyear ice (MYI, which has survived at least one melt season). The&#160; latter is of particular interest as it is usually thicker than other ice types (thus, takes more time to melt), much less saline, and may accommodate a unique ecosystem. Sea ice types in the Antarctic, until recently, have not been monitored much because of the lack of appropriate remote&#160; sensing methods. While the Antarctic sea ice is greatly dominated by FYI, there are, nevertheless, considerable amounts of MYI, in particular in the Weddell Sea. We have recently adapted an algorithm for the detection of Arctic sea ice types for application in the Antarctic. The algorithm uses data from space-borne microwave radiometers and scatterometers as input. So far we have compiled a time series of daily Antarctic MYI data (and also an estimate of YI and FYI) data at a spatial resolution of 12.5 km, starting in 2013, but excluding the melt seasons when the algorithm does not work. Here give an overview of the data, showing, e.g., the quite large interannual variability of MYI and its evolution in the Weddell Sea, and discuss shortcomings of the algorithm and possible ways forward. The time series of daily Antarctic MYI data can in principle be extended backwards to the year 2000, when the used satellite data first became available, and with planned future satellite missions, it can be continued for years to come.

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Arctic Ocean Sea Ice Area Extent Cyclicity and Non-Stationarity

10.5194/egusphere-egu2020-5915 ◽

2020 ◽

Author(s):

Reginald Muskett ◽

Syun-Ichi Akasofu

Keyword(s):

Time Series ◽

Sea Ice ◽

Wave Pattern ◽

Arctic Sea Ice ◽

The Arctic ◽

Weather System ◽

Sea Ice Extent ◽

Temperature Variations ◽

Arctic Sea ◽

Arctic Temperature

Arctic sea ice is a key component of the Arctic hydrologic cycle. This cycle is connected to land and ocean temperature variations and Arctic snow cover variations, spatially and temporally. Arctic temperature variations from historical observations shows an early 20th century increase (i.e. warming), followed by a period of Arctic temperature decrease (i.e. cooling) since the 1940s, which was followed by another period of Arctic temperature increase since the 1970s that continues into the two decades of the 21st century. Evidence has been accumulating that Arctic sea ice extent can experience multi-decadal to centennial time scale variations as it is a component of the Arctic Geohydrological System.&#160; We investigate the multi-satellite and sensor daily values of area extent of Arctic sea ice since SMMR on Nimbus 7 (1978) to AMSR2 on GCOM-W1 (2019). From the daily time series we use the first year-cycle as a wave-pattern to compare to all subsequent years-cycles through April 2020 (in progress), and constitute a derivative time series. In this time series we find the emergence of a multi-decadal cycle, showing a relative minimum during the period of 2007 to 2014, and subsequently rising. This may be related to an 80-year cycle (hypothesis). The Earth&#8217;s weather system is principally driven the solar radiation and its variations. If the multi-decadal cycle in Arctic sea ice area extent that we interpret continues, it may be linked physically to the Wolf-Gleissberg cycle, a factor in the variations of terrestrial cosmogenic isotopes, ocean sediment layering and glacial varves, ENSO and Aurora.Our hypothesis and results give more evidence that the multi-decadal variation of Arctic sea ice area extent is controlled by natural physical processes of the Sun-Earth system.&#160;

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