scholarly journals Impacts of sea ice on the marine iron cycle and phytoplankton productivity

2014 ◽  
Vol 11 (2) ◽  
pp. 2383-2418 ◽  
Author(s):  
S. Wang ◽  
D. Bailey ◽  
K. Lindsay ◽  
K. Moore ◽  
M. Holland
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Phytoplankton Production ◽  
Iron Cycle ◽  
Surface Ocean ◽  
Antarctic Sea Ice ◽  
Arctic Sea ◽  
Iron Concentrations

Abstract. Iron is a key nutrient for phytoplankton growth in the surface ocean. At high latitudes, the iron cycle is closely related to sea ice. In recent decades, Arctic sea ice cover has been declining rapidly and Antarctic sea ice has exhibited large regional trends. A significant reduction of sea ice in both hemispheres is projected in future climate scenarios. To study impacts of sea ice on the iron cycle, iron sequestration in ice is incorporated to the Biogeochemical Elemental Cycling (BEC) model. Sea ice acts as a reservoir of iron during winter and releases iron to the surface ocean in spring and summer. Simulated iron concentrations in sea ice generally agree with observations, in regions where iron concentrations are lower. The maximum iron concentrations simulated in the Arctic sea ice and the Antarctic sea ice are 192 nM and 134 nM, respectively. These values are much lower than observed, which is likely due to missing biological processes in sea ice. The largest iron source to sea ice is suspended sediments, contributing fluxes of iron of 2.2 × 108 mol Fe month−1 to the Arctic and 4.1 × 106 mol Fe month−1 to the Southern Ocean during summer. As a result of the iron flux from ice, iron concentrations increase significantly in the Arctic. Iron released from melting ice increases phytoplankton production in spring and summer and shifts phytoplankton community composition in the Southern Ocean. Simulation results for the period of 1998 to 2007 indicate that a reduction of sea ice in the Southern Ocean will have a negative influence on phytoplankton production. Iron transport by sea ice appears to be an important process bringing iron to the central Arctic. Impacts of iron fluxes from ice to ocean on marine ecosystems are negligible in the current Arctic Ocean, as iron is not typically the growth-limiting nutrient. However, it may become a more important factor in the future, particularly in the central Arctic, as iron concentrations will decrease with declining sea ice cover and transport.

scholarly journals Impact of sea ice on the marine iron cycle and phytoplankton productivity

2014 ◽  
Vol 11 (17) ◽  
pp. 4713-4731 ◽  
Author(s):  
S. Wang ◽  
D. Bailey ◽  
K. Lindsay ◽  
J. K. Moore ◽  
M. Holland
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Phytoplankton Production ◽  
Iron Cycle ◽  
Surface Ocean ◽  
Antarctic Sea Ice ◽  
Iron Concentrations

Abstract. Iron is a key nutrient for phytoplankton growth in the surface ocean. At high latitudes, the iron cycle is closely related to the dynamics of sea ice. In recent decades, Arctic sea ice cover has been declining rapidly and Antarctic sea ice has exhibited large regional trends. A significant reduction of sea ice in both hemispheres is projected in future climate scenarios. In order to adequately study the effect of sea ice on the polar iron cycle, sea ice bearing iron was incorporated in the Community Earth System Model (CESM). Sea ice acts as a reservoir for iron during winter and releases the trace metal to the surface ocean in spring and summer. Simulated iron concentrations in sea ice generally agree with observations in regions where iron concentrations are relatively low. The maximum iron concentrations simulated in Arctic and Antarctic sea ice are much lower than observed, which is likely due to underestimation of iron inputs to sea ice or missing mechanisms. The largest iron source to sea ice is suspended sediments, contributing fluxes of iron of 2.2 × 108 mol Fe month−1 in the Arctic and 4.1 × 106 mol Fe month−1 in the Southern Ocean during summer. As a result of the iron flux from ice, iron concentrations increase significantly in the Arctic. Iron released from melting ice increases phytoplankton production in spring and summer and shifts phytoplankton community composition in the Southern Ocean. Results for the period of 1998 to 2007 indicate that a reduction of sea ice in the Southern Ocean will have a negative influence on phytoplankton production. Iron transport by sea ice appears to be an important process bringing iron to the central Arctic. The impact of ice to ocean iron fluxes on marine ecosystems is negligible in the current Arctic Ocean, as iron is not typically the growth-limiting nutrient. However, it may become a more important factor in the future, particularly in the central Arctic, as iron concentrations will decrease with declining sea ice cover and transport.

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

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
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.

Mapping Antarctic sea ice albedo properties from MISR fused with MODIS

2020 ◽  
Author(s):  
Jan-Peter Muller ◽  
Said Kharbouche
Keyword(s):  
Sea Ice ◽  
Processing System ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
National Academy Of Sciences ◽  
Antarctic Sea Ice ◽  
Ice Coverage ◽  
Time Period ◽  
Arctic Sea ◽  
Academy Of Sciences

<p>In [1] a new method is described for fusing spectral BRF and derived albedo at 1.1km within the 7 minutes that MISR acquires images of a surface point with coincident MODIS nadir spectral data processed into a 1km sea ice mask. NetCDF products were produced in polar stereographic projection and produced on daily, weekly, fortnightly and monthly from November to February each year from 2000-2016. Arctic sea ice albedo has been previously presented and in this presentation, Antarctic time series, will be presented covering the same time period. This area has less complete coverage than the Arctic due to data outages due to telecommunications issues. [2] has recently pointed out that sea ice coverage  has  reduced dramatically since 2014, mainly one quadrant centred on the Wendell sea and the spectral albedo for this area will be highlighted.</p><p>Acknowledgements: Support was provided by EU-FP7 QA4ECV (Quality Assurance for Essential Climate Variables) under Project Number 607405 for the development of the processing system.</p><p>References:<br>[1] Kharbouche, S.; Muller, J.-P. Sea Ice Albedo from MISR and MODIS: Production, Validation, and Trend Analysis. Remote Sens. 2019, 11, 9. doi: https://doi.org/10.3390/rs11010009</p><p>[2] Parkinson, C. 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. 2019, 116 (29) 14414-14423; DOI: 10.1073/pnas.1906556116</p>

scholarly journals The Transient versus the Equilibrium Response of Sea Ice to Global Warming

2013 ◽  
Vol 26 (15) ◽  
pp. 5624-5636 ◽  
Author(s):  
Chao Li ◽  
Dirk Notz ◽  
Steffen Tietsche ◽  
Jochem Marotzke
Keyword(s):  
Sea Ice ◽  
Co2 Concentration ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Concentration Change ◽  
Antarctic Sea Ice ◽  
Equilibrium Response ◽  
Arctic Sea ◽  
Rapid Transition

Abstract To examine the long-term stability of Arctic and Antarctic sea ice, idealized simulations are carried out with the climate model ECHAM5/Max Planck Institute Ocean Model (MPI-OM). Atmospheric CO2 concentration is increased over 2000 years from preindustrial levels to quadrupling, is then kept constant for 5940 years, is afterward decreased over 2000 years to preindustrial levels, and is finally kept constant for 3940 years. Despite these very slow changes, the sea ice response significantly lags behind the CO2 concentration change. This lag, which is caused by the ocean's thermal inertia, implies that the sea ice equilibrium response to increasing CO2 concentration is substantially underestimated by transient simulations. The sea ice response to CO2 concentration change is not truly hysteretic and is in principle reversible. The authors find no lag in the evolution of Arctic sea ice relative to changes in annual-mean Northern Hemisphere surface temperature. The summer sea ice cover changes linearly with respect to both CO2 concentration and temperature, while the Arctic winter sea ice cover shows a rapid transition to a very low sea ice coverage. This rapid transition of winter sea ice is associated with a sharply enhanced ice–albedo feedback and a sudden onset of convective-cloud feedback in the Arctic. The Antarctic sea ice cover retreats continuously without any rapid transition during the warming. Compared to Arctic sea ice, Antarctic sea ice shows a much more strongly lagged response to changes in CO2 concentration. It even lags behind the surface temperature change, which is caused by a different response of ocean deep convection during the warming and the cooling periods.

The relative roles of Arctic and Antarctic sea-ice loss in the response to greenhouse warming

2021 ◽  
Author(s):  
Stephanie Hay ◽  
Paul Kusnher
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Climate Model ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice ◽  
Arctic Sea ◽  
Climate Model Simulations ◽  
Arctic Sea Ice Loss

<p>Antarctic sea ice has gradually increased in extent over the forty-year-long satellite record, in contrast with the clear decrease in sea-ice extent seen in the Arctic over the same time period. However, state-of-the-art climate models ubiquitously project Antarctic sea-ice to decrease over the coming century, much as they do for Arctic sea-ice. Several recent years have also seen record low Antarctic sea-ice. It is therefore of interest to understand what the climate response to Antarctic sea-ice loss will be. </p><p>We have carried out new fully coupled climate model simulations to assess the response to sea-ice loss in either hemisphere separately or coincidentally under different albedo parameter settings to determine the relative importance of each. By perturbing the albedo of the snow overlying the sea ice and the albedo of the bare sea ice, we obtain a suite of simulations to assess the linearity and additivity of sea-ice loss. We find the response to sea-ice loss in each hemisphere exhibits a high degree of additivity, and can simply be decomposed into responses due to loss in each hemisphere separately. We find that the response to Antarctic sea-ice loss exceeds that of Arctic sea-ice loss in the tropics, and that Antarctic sea-ice loss leads to statistically significant Arctic warming, while the opposite is not true.</p><p>With these new simulations and one in which CO<sub>2</sub> is instantaneously doubled , we can further characterize the response to sea-ice loss from each hemisphere using an extension to classical pattern scaling that includes three controlling parameters. This allows us to simultaneously compute the sensitivity patterns to Arctic sea-ice loss, Antarctic sea-ice loss, and to tropical warming. The statistically significant response to Antarctic sea-ice loss in the Northern Hemisphere extratropics is found to be mediated by tropical warming and small amounts of Arctic sea-ice loss.</p>

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

2017 ◽  
Vol 11 (5) ◽  
pp. 2111-2116 ◽  
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.

scholarly journals Relationship of the Extent of Antarctic and Arctic Ice with Temperature Changes, 1979–2020

2021 ◽  
Vol 496 (1) ◽  
pp. 66-71
Author(s):  
I. I. Mokhov ◽  
M. R. Parfenova
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Surface Air Temperature ◽  
Sharp Decrease ◽  
Reanalysis Data ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Antarctic Sea Ice ◽  
Arctic Sea ◽  
Cross Wavelet Analysis

Abstract Quantitative estimates of the relationship between interannual variations in the extent of Antarctic and Arctic sea ice and changes in the surface air temperature in the Northern and Southern hemispheres are obtained using satellite, ground-based, and reanalysis data for the past four decades (1980–2019). It is shown that the previously noted general increase in the extent of Antarctic sea ice observed until recent years from satellite data (available only since the late 1970s) over the background global warming and a rapid decrease in the extent of Arctic sea ice is associated with a regional decrease in the surface temperature at Antarctic latitudes from the end of the 1970s. This is a result of regional manifestation of natural climate variations with periods of up to several decades against the background of global secular warming with a relatively weak temperature trend over the ocean in the Southern Hemisphere. Since 2016, a sharp decrease in the extent of Antarctic sea ice in the Southern Ocean has been observed. The results of the correlation and cross-wavelet analysis indicate significant coherence and negative correlation with the surface temperature of the extent of sea ice in recent decades, not only in the Arctic, but also in the Antarctic.

scholarly journals A lead-width distribution for Antarctic sea ice: a case study for the Weddell Sea with high resolution Sentinel-2 images

2020 ◽  
Author(s):  
Marek Muchow ◽  
Amelie U. Schmitt ◽  
Lars Kaleschke
Keyword(s):  
Sea Ice ◽  
Power Law ◽  
Arctic Sea Ice ◽  
Weddell Sea ◽  
The Arctic ◽  
Antarctic Sea Ice ◽  
Fitting Method ◽  
Arctic Sea ◽  
Width Distribution ◽  
Sentinel 2

Abstract. We derive for the first time a statistical lead-width distribution for Antarctic sea ice using Weddell sea ice as a case study. Therefore, we transfer previous approaches for Arctic sea ice with a power law with a positive exponent (p(xwidth) xwidth−a, a > 1) to Antarctic sea ice. We use 20 carefully selected cloud-free Copernicus Sentinel-2 images from November 2016 until February 2018, covering only the months from November to April. In doing so we compare exponents given in the literature for the Arctic sea ice, who do not agree with each other, to Antarctic sea ice. To detect leads we create a sea ice surface type classification for the Sentinel-2 Level 1C data products, which are selected due to their high spatial resolution of 10 m. We apply two different fitting methods to the measured lead widths, which have been used in previous studies for Arctic sea ice. The first fitting method is a linear fit, while the second method is based on a maximum likelihood approach. Here, we use both methods for the same lead-width data set to observe differences in the calculated power law exponent. To further investigate influences on the power law exponent, we define two different lead thresholds for open water and nilas. The influence of the lead threshold on the exponent is bigger for the linear fit than for the method based on the maximum likelihood approach. We show that the exponent of the lead-width distribution ranges between 1.16 to 1.41 depending on the applied fitting method and lead threshold. This exponent for the Weddell sea ice is smaller than the previously observed exponents for the Arctic sea ice.

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

<p>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.</p><p>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.</p>

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

2015 ◽  
Vol 56 (69) ◽  
pp. 18-28 ◽  
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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