Comparison of modern and fossil diatom assemblages and their implication on sea-ice conditions in coastal Antarctic region

Antarctic Coastal regions are thought to be characterized by high productivity usually dominated by diatoms. Considering their prime importance in global carbon biological pump, diatom distribution and abundance studies are sparse especially in coastal regions of Antarctica. Biogenic silica is considered to be severely affected by dissolution in the undersaturated ocean water, therefore, combined study of diatom assemblages from water column and those found in the sediments is important. Therefore, we conducted a combined study of sediment diatoms along with surface water diatoms collected from Coastal Antarctica. When the modern assemblages are compared to the fossil record, it is clear the most of the important diatoms from the summer assemblages are not preserved in the underlying sediments. The studies reveal that only F. kerguelensis is common abundant species in both water and sediment which suggests that coastal Antarctic region could be having more open ocean influence. In contrast, the presence of sea ice related diatom species from surface sediment indicate for expansion of sea ice or ice edge adjacent to the water column, however such species were not found in the overlying water samples which could be due to less sea-ice extent.

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Holocene climate variations in the western Antarctic Peninsula: evidence for sea ice extent predominantly controlled by changes in insolation and ENSO variability

Climate of the Past ◽

10.5194/cp-9-1431-2013 ◽

2013 ◽

Vol 9 (4) ◽

pp. 1431-1446 ◽

Cited By ~ 47

Author(s):

J. Etourneau ◽

L. G. Collins ◽

V. Willmott ◽

J.-H. Kim ◽

L. Barbara ◽

...

Keyword(s):

Sea Ice ◽

Water Column ◽

Antarctic Peninsula ◽

Primary Productivity ◽

Climatic Factors ◽

Southern Oscillation ◽

Western Antarctic Peninsula ◽

Deep Basin ◽

Sea Ice Extent ◽

Ice Conditions

Abstract. The West Antarctic ice sheet is particularly sensitive to global warming and its evolution and impact on global climate over the next few decades remains difficult to predict. In this context, investigating past sea ice conditions around Antarctica is of primary importance. Here, we document changes in sea ice presence, upper water column temperatures (0–200 m) and primary productivity over the last 9000 yr BP (before present) in the western Antarctic Peninsula (WAP) margin from a sedimentary core collected in the Palmer Deep Basin. Employing a multi-proxy approach, based on the combination of two biomarkers proxies (highly branched isoprenoid (HBI) alkenes for sea ice and TEX86L for temperature) and micropaleontological data (diatom assemblages), we derived new Holocene records of sea ice conditions and upper water column temperatures. The early Holocene (9000–7000 yr BP) was characterized by a cooling phase with a short sea ice season. During the mid-Holocene (~7000–3800 yr BP), local climate evolved towards slightly colder conditions and a prominent extension of the sea ice season occurred, promoting a favorable environment for intensive diatom growth. The late Holocene (the last ~2100 yr) was characterized by warmer temperatures and increased sea ice presence, accompanied by reduced local primary productivity, likely in response to a shorter growing season compared to the early or mid-Holocene. The gradual increase in annual sea ice duration over the last 7000 yr might have been influenced by decreasing mean annual and spring insolation, despite increasing summer insolation. We postulate that, in addition to precessional changes in insolation, seasonal variability, via changes in the strength of the circumpolar Westerlies and upwelling activity, was further amplified by the increasing frequency/amplitude of the El Niño–Southern Oscillation (ENSO). However, between 3800 and 2100 yr BP, the lack of correlation between ENSO and climate variability in the WAP suggests that other climatic factors might have been more important in controlling WAP climate at this time.

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Holocene climate variations in the western Antarctic Peninsula: evidence for sea ice extent predominantly controlled by insolation and ENSO variability changes

Climate of the Past Discussions ◽

10.5194/cpd-9-1-2013 ◽

2013 ◽

Vol 9 (1) ◽

pp. 1-41 ◽

Cited By ~ 3

Author(s):

J. Etourneau ◽

L. G. Collins ◽

V. Willmott ◽

J. H. Kim ◽

L. Barbara ◽

...

Keyword(s):

Sea Ice ◽

Water Column ◽

Antarctic Peninsula ◽

Primary Productivity ◽

Climatic Factors ◽

Southern Oscillation ◽

Western Antarctic Peninsula ◽

Deep Basin ◽

Sea Ice Extent ◽

Ice Conditions

Abstract. The West Antarctic ice sheet is particularly sensitive to global warming and its evolution and impact on global climate over the next few decades remains difficult to predict. In this context, investigating past sea ice conditions around Antarctica is of primary importance. Here, we document changes in sea ice presence, upper water column temperatures (0–200 m) and primary productivity over the last 9000 yr BP (before present) in the western Antarctic Peninsula (WAP) margin from a sedimentary core collected in the Palmer Deep basin. Employing a multi-proxy approach, we derived new Holocene records of sea ice conditions and upper water column temperatures, based on the combination of two biomarkers proxies (highly branched isoprenoid (HBI) alkenes for sea ice and TEXL86 for temperature) and micropaleontological data (diatom assemblages). The early Holocene (9000–7000 yr BP) was characterized by a cooling phase with a short sea ice season. During the mid-Holocene (~ 7000–3000 yr BP), local climate evolved towards slightly colder conditions and a prominent extension of the sea ice season occurred, promoting a favorable environment for intensive diatom growth. The late Holocene (the last ~ 3000 yr) was characterized by more variable temperatures and increased sea ice presence, accompanied by reduced local primary productivity likely in response to a shorter growing season compared to the early or mid-Holocene. The stepwise increase in annual sea ice duration over the last 7000 yr might have been influenced by decreasing mean annual and spring insolation despite an increasing summer insolation. We postulate that in addition to precessional changes in insolation, seasonal variability, via changes in the strength of the circumpolar Westerlies and upwelling activity, was further amplified by the increasing frequency/amplitude of El Niño-Southern Oscillation (ENSO). However, between 4000 and 2100 yr BP, the lack of correlation between ENSO and climate variability in the WAP suggests that other climatic factors might have been more important in controlling WAP climate at this time.

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Arctic seabirds and shrinking sea ice: egg analyses reveal the importance of ice-derived resources

Scientific Reports ◽

10.1038/s41598-019-51788-4 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Fanny Cusset ◽

Jérôme Fort ◽

Mark Mallory ◽

Birgit Braune ◽

Philippe Massicotte ◽

...

Keyword(s):

Sea Ice ◽

Marine Species ◽

Arctic Sea Ice ◽

The Arctic ◽

Sea Ice Extent ◽

Climate Shifts ◽

Investment In Reproduction ◽

Ice Conditions ◽

Arctic Seabirds ◽

Energetic Composition

Abstract In the Arctic, sea-ice plays a central role in the functioning of marine food webs and its rapid shrinking has large effects on the biota. It is thus crucial to assess the importance of sea-ice and ice-derived resources to Arctic marine species. Here, we used a multi-biomarker approach combining Highly Branched Isoprenoids (HBIs) with δ13C and δ15N to evaluate how much Arctic seabirds rely on sea-ice derived resources during the pre-laying period, and if changes in sea-ice extent and duration affect their investment in reproduction. Eggs of thick-billed murres (Uria lomvia) and northern fulmars (Fulmarus glacialis) were collected in the Canadian Arctic during four years of highly contrasting ice conditions, and analysed for HBIs, isotopic (carbon and nitrogen) and energetic composition. Murres heavily relied on ice-associated prey, and sea-ice was beneficial for this species which produced larger and more energy-dense eggs during icier years. In contrast, fulmars did not exhibit any clear association with sympagic communities and were not impacted by changes in sea ice. Murres, like other species more constrained in their response to sea-ice variations, therefore appear more sensitive to changes and may become the losers of future climate shifts in the Arctic, unlike more resilient species such as fulmars.

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Sea ice metadata for Billefjorden and Grnfjorden, Svalbard

Czech Polar Reports ◽

10.5817/cpr2014-2-13 ◽

2014 ◽

Vol 4 (2) ◽

pp. 129-139 ◽

Cited By ~ 1

Author(s):

Boris V. Ivanov ◽

Pavel N. Sviashchennikov ◽

Danila M. Zhuravskiy ◽

Alexey K. Pavlov ◽

Eirik J. Frland ◽

...

Keyword(s):

Climate Change ◽

Sea Ice ◽

State Archive ◽

Sea Ice Extent ◽

Sea Transport ◽

Local Climate ◽

Antarctic Research Institute ◽

Instrumental Observations ◽

Ice Conditions ◽

Antarctic Research

Description of sea ice conditions in the fjords of Svalbard is crucial for sea transport as well as studies of local climate and climate change. Old observations from the Russian Hydrometeorological stations in the mining settlements Barentsburg (Grnfjorden) and Pyramiden (Billefjorden) have now been digitized. These visual and instrumental observations are archived in the State Archive of Arctic and Antarctic Research Institute (AARI) and Murmansk Branch of the Russian Hydrometeorological Service. In this paper, we bring an overview of the sea ice metadata with few examples of yearly changes in sea ice extent.

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Sea ice and atmosphere interactions and predictability: preliminary results using HadGEM3

10.5194/egusphere-egu2020-13771 ◽

2020 ◽

Author(s):

Daniela Flocco ◽

Ed Hawkins ◽

Leandro Ponsoni ◽

Francois Massonnet ◽

Daniel Feltham ◽

...

Keyword(s):

Sea Ice ◽

Initial Conditions ◽

Complete Information ◽

Arctic Sea Ice ◽

The Arctic ◽

Sea Ice Extent ◽

Sea Level Pressure ◽

Sea Ice Thickness ◽

Climate Forecasts ◽

Ice Conditions

Arctic sea ice extent has steadily declined in the past 30 years. Aside from the global impact on climate change, regional information on the sea ice presence and on its impact on oceanic and atmospheric patterns has witnessed a growing interest. There is a growing need for seasonal-to-decadal timescale climate forecasts to help inform local communities and industry stakeholders.Here we examine the influence of sea-ice thickness observations on the predictability of the sea-ice and atmospheric circulation. We perform paired sets of ensembles with the HadGEM3 GCM starting from different initial conditions in a present-day control run. One set of ensembles start with complete information about the sea-ice conditions, and one set have degraded information. We investigate how the pairs of ensembles predict the subsequent evolution of the sea-ice, sea level pressure and circulation within the Arctic and beyond with the aim of quantifying the value of sea-ice observations for improving predictions.

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Comparison of sea-ice extent and ice-edge location estimates from passive microwave and enhanced-resolution scatterometer data

Annals of Glaciology ◽

10.3189/172756408784700743 ◽

2008 ◽

Vol 48 ◽

pp. 65-70 ◽

Cited By ~ 32

Author(s):

Walter N. Meier ◽

Julienne Stroeve

Keyword(s):

Sea Ice ◽

Resolution Enhancement ◽

Passive Microwave ◽

Sea Ice Concentration ◽

Sea Ice Extent ◽

Local Conditions ◽

Enhanced Resolution ◽

Edge Location ◽

Ice Conditions ◽

Ice Edge

AbstractPassive microwave sea-ice concentration fields provide some of the longest-running and most consistent records of changes in sea ice. Scatterometry-based sea-ice fields are more recently developed data products, but now they provide a record of ice conditions spanning several years. Resolution enhancement techniques applied to scatterometer fields provide much higher effective resolutions (~10 km) than are available from standard scatterometer and passive microwave fields (25–50 km). Here we examine ice-extent fields from both sources and find that there is general agreement between scatterometer data and passive microwave fields, though scatterometer estimates yield substantially lower ice extents during winter. Comparisons with ice-edge locations estimated from AVHRR imagery indicate that enhanced scatterometer data can sometimes provide an improved edge location, but there is substantial variation in the results, depending on the local conditions. A blended product, using both scatterometer and passive microwave data, could yield improved results.

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Records of sea-ice extent and air temperature at the Sea of Okhotsk from an ice core of Mount Ichinsky, Kamchatka

Annals of Glaciology ◽

10.3189/172756411797252149 ◽

2011 ◽

Vol 52 (58) ◽

pp. 44-50 ◽

Cited By ~ 9

Author(s):

Sumito Matoba ◽

Takayuki Shiraiwa ◽

Akane Tsushima ◽

Hirotaka Sasaki ◽

Yaroslav D. Muravyev

Keyword(s):

Sea Ice ◽

Sea Of Okhotsk ◽

Thermohaline Circulation ◽

Ice Core ◽

Solar Irradiation ◽

Sea Ice Extent ◽

Arctic Oscillation Index ◽

High Productivity ◽

The Sea Of Okhotsk ◽

Ice Production

AbstarctThe Sea of Okhotsk is the southernmost area in the Northern Hemisphere where seasonal sea ice is produced every year. The formation of sea ice drives thermohaline circulation in the Sea of Okhotsk, and this circulation supports the high productivity in the region. However, recent reports have indicated that sea-ice production in the Sea of Okhotsk is decreasing, raising concern that the decreased sea ice will affect not only circulation but also biological productivity in the sea. To reconstruct climatic changes in the Sea of Okhotsk region, we analyzed an ice core obtained from Ichinskaya Sopka (Mount Ichinsky), Kamchatka. We assumed that the remarkable negative peaks of δD in the ice core were caused by expansion of sea ice in the Sea of Okhotsk. Melt feature percentage (MFP), which indicates summer snowmelt, showed high values in the 1950–60s and the mid-1990s–2000s. The high MFP in the 1950–60s was assumed to be caused by an increase in cyclone activity reaching Kamchatka during a negative period of the Pacific Decadal Oscillation index, and that in the 1990–2000s may reflect the increase in solar irradiation during a positive period of the summer Arctic Oscillation index.

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Sea Ice Extent Detection in the Bohai Sea Using Sentinel-3 OLCI Data

Remote Sensing ◽

10.3390/rs11202436 ◽

2019 ◽

Vol 11 (20) ◽

pp. 2436 ◽

Cited By ~ 2

Author(s):

Hua Su ◽

Bowen Ji ◽

Yunpeng Wang

Keyword(s):

Sea Ice ◽

Bohai Sea ◽

Regional Climate ◽

Regional Climate Change ◽

The Novel ◽

Sea Ice Extent ◽

Important Indicator ◽

The Bohai Sea ◽

Information Index ◽

Ice Conditions

Sea ice distribution is an important indicator of ice conditions and regional climate change in the Bohai Sea (China). In this study, we monitored the spatiotemporal distribution of the Bohai Sea ice in the winter of 2017–2018 by developing sea ice information indexes using 300 m resolution Sentinel-3 Ocean and Land Color Instrument (OLCI) images. We assessed and validated the index performance using Sentinel-2 MultiSpectral Instrument (MSI) images with higher spatial resolution. The results indicate that the proposed Normalized Difference Sea Ice Information Index (NDSIIIOLCI), which is based on OLCI Bands 20 and 21, can be used to rapidly and effectively detect sea ice but is somewhat affected by the turbidity of the seawater in the southern Bohai Sea. The novel Enhanced Normalized Difference Sea Ice Information Index (ENDSIIIOLCI), which builds on NDSIIIOLCI by also considering OLCI Bands 12 and 16, can monitor sea ice more accurately and effectively than NDSIIIOLCI and suffers less from interference from turbidity. The spatiotemporal evolution of the Bohai Sea ice in the winter of 2017–2018 was successfully monitored by ENDSIIIOLCI. The results show that this sea ice information index based on OLCI data can effectively extract sea ice extent for sediment-laden water and is well suited for monitoring the evolution of Bohai Sea ice in winter.

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Dynamical mechanism of the poleward intensification of the Southern Hemispheric Westerlies due to sea ice extent change

10.5194/egusphere-egu2020-15627 ◽

2020 ◽

Author(s):

Hyeong-Gyu Kim ◽

Joowan Kim ◽

Sang-Yoon Jun ◽

Seong-Joong Kim

Keyword(s):

Southern Ocean ◽

Sea Ice ◽

Ocean Circulation ◽

Atmospheric Temperature ◽

Sea Ice Extent ◽

Dynamical Mechanism ◽

Antarctic Sea Ice ◽

Crucial Component ◽

Ice Conditions ◽

Geological Timescale

Paleoclimate data shows a good correlation between the concentration of CO2 and atmospheric temperature in the geological timescale. Many studies compare the Last Glacial Maximum (LGM) and the Pre-Industrial era (PI), to understand the coupling processes. A popular mechanism explaining this coupling process is a modulation of the ocean circulation and related CO2 emission over the Southern Ocean due to atmospheric westerly. The atmospheric westerly plays an important role in driving ocean circulation; however, the related processes are not fully understood for the LGM period.In this study, we examine physical processes determining the characteristics of the atmospheric westerly focusing on the Southern Ocean. Atmospheric states for LGM and PI are reproduced using a coupled earth system model with different sea ice conditions. A poleward intensification of the Southern Hemispheric Westerlies is observed for the LGM experiment. A comparison to PI shows that the meridional temperature gradient largely determines this intensification, and the enhanced meridional gradient is observed due to decreased heat flux from the subantarctic ocean in the LGM experiment. This result suggests that the Antarctic sea ice is a crucial component for understanding the Southern Hemispheric Westerly.

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Comparison of the microalgal community within fast ice at two sites along the Ross Sea coast, Antarctica

Antarctic Science ◽

10.1017/s0954102006000629 ◽

2006 ◽

Vol 18 (4) ◽

pp. 583-594 ◽

Cited By ~ 29

Author(s):

K.G. Ryan ◽

E.N. Hegseth ◽

A. Martin ◽

S.K. Davy ◽

R. O'Toole ◽

...

Keyword(s):

Sea Ice ◽

Water Column ◽

Dominant Species ◽

Ross Sea ◽

Standing Stock ◽

Cylindrotheca Closterium ◽

Strong Current ◽

Ice Conditions ◽

Fast Ice ◽

And Function

Diverse microbial communities survive within the sea ice matrix and are integral to the energy base of the Southern Ocean. Here we describe initial findings of a four season survey (between 1999–2004) of community structure and biomass of microalgae within the sea ice and in the underlying water column at Cape Evans and Cape Hallett, in the Ross Sea, Antarctica as part of the Latitudinal Gradient Project. At Cape Evans, bottom-ice chlorophyll a levels ranged from 4.4 to 173 mg Chl a m−2. Dominant species were Nitzschia stellata, N. lecointei, and Entomoneis kjellmanii, while the proportion of Berkeleya adeliensis increased steadily during spring. Despite being obtained later in the season, the Cape Hallett data show considerably lower standing stocks of chlorophyll ranging from 0.11 to 36.8 mg Chl a m−2. This difference was attributed to a strong current, which may have ablated much of the bottom ice biomass and provided biomass to the water below. This loss of algae from the bottom of the ice may explain why the ice community contributed only 2% of the standing stock in the total water column. Dominant species at Cape Hallett were Nitzschia stellata, Fragilariopsis curta and Cylindrotheca closterium. The low biomass at Cape Hallett and the prevalence of smaller-celled diatoms in the bottom ice community indicate that the ice here is more typical of pack ice than fast ice. Further data will allow us to quantify and model the extent to which ice-driven dynamics control the structure and function of the sea ice ecosystem and to assess its resilience to changing sea ice conditions.

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