scholarly journals Phytoplankton and dimethylsulfide dynamics at two contrasting Arctic ice edges

2019 ◽  
Author(s):  
Martine Lizotte ◽  
Maurice Levasseur ◽  
Virginie Galindo ◽  
Margaux Gourdal ◽  
Michel Gosselin ◽  
...  
Keyword(s):  
Sea Ice ◽  
High Arctic ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
First Year ◽  
Chl A ◽  
Nares Strait ◽  
Ice Edge ◽  
Arctic Ice ◽  
Rate Of Decline

Abstract. Arctic sea ice is retreating, thinning and its rate of decline has steepened in the last decades. While phytoplankton blooms are known to seasonally propagate along the ice edge as it recedes from spring to summer, the substitution of thick multi-year ice (MYI) with thinner, ponded first-year ice (FYI) represents an unequal exchange when considering the roles sea ice plays in the ecology and climate of the Arctic. Consequences of this shifting sea ice on the phenology of phytoplankton and the associated cycling of the climate-relevant gas dimethylsulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) remain ill constrained. In July–August 2014, two contrasting ice edges in the Canadian High Arctic were explored: a FYI-dominated ice edge in Barrow Strait and a MYI-dominated ice edge in Nares Strait. Our results reveal two distinct planktonic systems and associated DMS dynamics in connection to these diverging ice types. The surface waters exiting the ponded FYI in Barrow Strait were characterized by moderate chlorophyll a (Chl a,

scholarly journals Phytoplankton and dimethylsulfide dynamics at two contrasting Arctic ice edges

2020 ◽  
Vol 17 (6) ◽  
pp. 1557-1581 ◽  
Author(s):  
Martine Lizotte ◽  
Maurice Levasseur ◽  
Virginie Galindo ◽  
Margaux Gourdal ◽  
Michel Gosselin ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Waters ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Chl A ◽  
Melt Pond ◽  
Nares Strait ◽  
Arctic Sea ◽  
Ice Edge ◽  
Methylated Sulfur Compounds

Abstract. Arctic sea ice is retreating and thinning and its rate of decline has steepened in the last decades. While phytoplankton blooms are known to seasonally propagate along the ice edge as it recedes from spring to summer, the substitution of thick multiyear ice (MYI) with thinner, ponded first-year ice (FYI) represents an unequal exchange when considering the roles sea ice plays in the ecology and climate of the Arctic. Consequences of this shifting sea ice on the phenology of phytoplankton and the associated cycling of the climate-relevant gas dimethylsulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) remain ill constrained. In July–August 2014, two contrasting ice edges in the Canadian High Arctic were explored: a FYI-dominated ice edge in Barrow Strait and a MYI-dominated ice edge in Nares Strait. Our results reveal two distinct planktonic systems and associated DMS dynamics in connection to these diverging ice types. The surface waters exiting the ponded FYI in Barrow Strait were characterized by moderate chlorophyll a (Chl a, <2.1 µg L−1) as well as high DMSP (115 nmol L−1) and DMS (12 nmol L−1), suggesting that a bloom had already started to develop under the markedly melt-pond-covered (ca. 40 %) FYI. Heightened DMS concentrations at the FYI edge were strongly related to ice-associated seeding of DMS in surface waters and haline-driven stratification linked to ice melt (Spearman's rank correlation between DMS and salinity, rs=-0.91, p<0.001, n=20). However, surface waters exiting the MYI edge at the head of Nares Strait were characterized by low concentrations of Chl a (<0.5 µg L−1), DMSP (<16 nmol L−1), and DMS (<0.4 nmol L−1), despite the nutrient-replete conditions characterizing the surface waters. The increase in autotrophic biomass and methylated sulfur compounds took place several kilometers (ca. 100 km) away from the MYI edge, suggesting the requisite for ice-free, light-sufficient conditions for a phytoplankton bloom to fully develop and for sulfur compound dynamics to follow and expand. In light of the ongoing and projected climate-driven changes to Arctic sea ice, results from this study suggest that the early onset of autotrophic blooms under thinner, melt-pond-covered ice may have vast implications for the timing and magnitude of DMS pulses in the Arctic.

scholarly journals Anomalous collapses of Nares Strait ice arches leads to enhanced export of Arctic sea ice

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
G. W. K. Moore ◽  
S. E. L. Howell ◽  
M. Brady ◽  
X. Xu ◽  
K. McNeil
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
The Past ◽  
Nares Strait ◽  
Arctic Sea ◽  
Arctic Ice ◽  
Ice Pack ◽  
Area And Volume

AbstractThe ice arches that usually develop at the northern and southern ends of Nares Strait play an important role in modulating the export of Arctic Ocean multi-year sea ice. The Arctic Ocean is evolving towards an ice pack that is younger, thinner, and more mobile and the fate of its multi-year ice is becoming of increasing interest. Here, we use sea ice motion retrievals from Sentinel-1 imagery to report on the recent behavior of these ice arches and the associated ice fluxes. We show that the duration of arch formation has decreased over the past 20 years, while the ice area and volume fluxes along Nares Strait have both increased. These results suggest that a transition is underway towards a state where the formation of these arches will become atypical with a concomitant increase in the export of multi-year ice accelerating the transition towards a younger and thinner Arctic ice pack.

scholarly journals Increasing Mobility of High Arctic Sea Ice Increases Marine Hazards off the East Coast of Newfoundland

2021 ◽  
Author(s):  
David Babb ◽  
David Barber ◽  
Jens Ehn ◽  
Wayne Chan ◽  
Lisa Mathes ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Maritime Industry ◽  
Baffin Bay ◽  
Nares Strait ◽  
Fishing Vessels ◽  
Arctic Ice ◽  
Ice Pack

&lt;p&gt;As the Arctic ice cover has transitioned to a younger and thinner state it has become weaker and therefore increasingly mobile. One of the key indicators of this change is the increase in ice flux through Nares Strait, which connects the central Arctic to Baffin Bay and is an export pathway for some of the oldest and thickest sea ice remaining within the Arctic. Historically ice flux through the narrow Strait was seasonally limited by the formation of an ice arch, however as the ice cover has thinned the arch no longer forms every winter, and when it does form it tends to break up earlier. An increase in ice flux through Nares Strait not only affects the retention of old thick ice within the central Arctic, but also affects the icescape downstream of the Strait that extends from Baffin Bay, through the Labrador Sea and towards the southern ice edge around Newfoundland. While an ice cover does form annually around Newfoundland, it is typically a thin seasonal ice cover, which forms in January and is gone by May. However, during spring 2017 the ice conditions were considerably heavier, presenting hazardous conditions for the local maritime industry into June and requiring the Canadian Coast Guard research ice breaker Amundsen be pulled off of its scientific cruise and used to escort vessels and conduct search and rescue operations along Newfoundland&amp;#8217;s northeast coast. The ice cover was considerably thicker and more extensive than previous years and sank two fishing vessels that became beset within the ice pack. Using a unique suite of in situ observations we confirmed that multiyear sea ice from the central Arctic was present within this anomalous ice cover. Using satellite imagery and regional ice charts we tracked the source of this multiyear ice back to Nares Strait and the central Arctic. While regional in focus, this work highlights how the decline of the Arctic ice pack has implications for downstream areas where risk may be increasing as the ice pack declines.&lt;/p&gt;

Winter Arctic sea ice freeboard, snow depth and thickness variability from ICESat-2 and NESOSIM

2021 ◽  
Author(s):  
Alek Petty ◽  
Nicole Keeney ◽  
Alex Cabaj ◽  
Paul Kushner ◽  
Nathan Kurtz ◽  
...  
Keyword(s):  
Sea Ice ◽  
Snow Depth ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Ice Cloud ◽  
Ice Drift ◽  
Thickness Variability ◽  
Arctic Ice

&lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;p&gt;National Aeronautics and Space Administration's (NASA's) Ice, Cloud, and land Elevation Satellite&amp;#8208; 2 (ICESat&amp;#8208;2) mission was launched in September 2018 and is now providing routine, very high&amp;#8208;resolution estimates of surface height/type (the ATL07 product) and freeboard (the ATL10 product) across the Arctic and Southern Oceans. In recent work we used snow depth and density estimates from the NASA Eulerian Snow on Sea Ice Model (NESOSIM) together with ATL10 freeboard data to estimate sea ice thickness across the entire Arctic Ocean. Here we provide an overview of updates made to both the underlying ATL10 freeboard product and the NESOSIM model, and the subsequent impacts on our estimates of sea ice thickness including updated comparisons to the original ICESat mission and ESA&amp;#8217;s CryoSat-2. Finally we compare our Arctic ice thickness estimates from the 2018-2019 and 2019-2020 winters and discuss possible causes of these differences based on an analysis of atmospheric data (ERA5), ice drift (NSIDC) and ice type (OSI SAF).&lt;/p&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt;

scholarly journals Interpretation of Slar Imagery of Sea Ice in Nares Strait and the Arctic Ocean

1975 ◽  
Vol 15 (73) ◽  
pp. 193-213
Author(s):  
Moira Dunbar
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
North Pole ◽  
The Arctic ◽  
Canadian Forces ◽  
Nares Strait ◽  
The North ◽  
The Arctic Ocean ◽  
Ice Edge ◽  
Airborne Sensors

AbstractSLAR imagery of Nares Strait was obtained on three flights carried out in. January, March, and August of 1973 by Canadian Forces Maritime Proving and Evaluation Unit in an Argus aircraft equipped with a Motorola APS-94D SLAR; the March flight also covered two lines in the Arctic Ocean, from Alert 10 the North Pole and from the Pole down the long. 4ºE. meridian to the ice edge at about lat. 80º N. No observations on the ground were possible, but -some back-up was available on all flights from visual observations recorded in the air, and on the March flight from infrared line-scan and vertical photography.The interpretation of ice features from the SLAR imagery is discussed, and the conclusion reached that in spite of certain ambiguities the technique has great potential which will increase with improving resolution, Extent of coverage per distance flown and independence of light and cloud conditions make it unique among airborne sensors.

scholarly journals Melt pond distribution and geometry in high Arctic sea ice derived from aerial investigations

2016 ◽  
Vol 57 (73) ◽  
pp. 105-118 ◽  
Author(s):  
W. Huang ◽  
P. Lu ◽  
R. Lei ◽  
H. Xie ◽  
Z. Li
Keyword(s):  
Sea Ice ◽  
Ground Truth ◽  
High Arctic ◽  
Arctic Sea Ice ◽  
Melt Pond ◽  
Melt Ponds ◽  
Ice Concentration ◽  
Areal Fraction ◽  
Pond Size ◽  
Arctic Ice

ABSTRACTAerial photography was conducted in the high Arctic Ocean during a Chinese research expedition in summer 2010. By partitioning the images into three distinct surface categories (sea ice/snow, water and melt ponds), the areal fraction of each category, ice concentration and the size and geometry of individual melt ponds, are determined with high-spatial resolution. The ice concentration and melt pond coverage have large spatial deviations between flights and even between images from the marginal ice zone to the pack ice zone in the central Arctic. Ice concentration and pond coverage over high Arctic (from 84°N to north) was ~75% and ~6.8%, respectively, providing ‘ground truth’ for the unusual transpolar reduction strip of ice indicated concurrently by AMSR-E data and for the regions (north of 88°N) where no passive microwave sensors can cover. Melt pond size and shape distributions are examined in terms of pond area (S), perimeter (P), mean caliper dimension (MCD) (L), roundness (R), convex degree (C), the ratio of P/S and fractal dimension (D). Power-law relationships are developed between pond size and number. Some general trends in geometric metrics are identified as a function of pond area including R, C, P/S and D. The scale separation of pond complexity is demonstrated by analyzing area-perimeter data. The results will potentially help the modelling of melt pond evolution and the determination of heterogeneity of under-ice transmitted light fields.

scholarly journals Variability scaling and consistency in airborne and satellite altimetry measurements of Arctic sea ice

2020 ◽  
Vol 14 (2) ◽  
pp. 751-767
Author(s):  
Shiming Xu ◽  
Lu Zhou ◽  
Bin Wang
Keyword(s):  
Remote Sensing ◽  
Sea Ice ◽  
Snow Depth ◽  
Spatial Scales ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
First Year ◽  
Noise Levels ◽  
Wide Range

Abstract. Satellite and airborne remote sensing provide complementary capabilities for the observation of the sea ice cover. However, due to the differences in footprint sizes and noise levels of the measurement techniques, as well as sea ice's variability across scales, it is challenging to carry out inter-comparison or consistently study these observations. In this study we focus on the remote sensing of sea ice thickness parameters and carry out the following: (1) the analysis of variability and its statistical scaling for typical parameters and (2) the consistency study between airborne and satellite measurements. By using collocating data between Operation IceBridge and CryoSat-2 (CS-2) in the Arctic, we show that consistency exists between the variability in radar freeboard estimations, although CryoSat-2 has higher noise levels. Specifically, we notice that the noise levels vary among different CryoSat-2 products, and for the European Space Agency (ESA) CryoSat-2 freeboard product the noise levels are at about 14 and 20 cm for first-year ice (FYI) and multi-year ice (MYI), respectively. On the other hand, for Operation IceBridge and NASA's Ice, Cloud, and land Elevation Satellite (ICESat), it is shown that the variability in snow (or total) freeboard is quantitatively comparable despite more than a 5-year time difference between the two datasets. Furthermore, by using Operation IceBridge data, we also find widespread negative covariance between ice freeboard and snow depth, which only manifests on small spatial scales (40 m for first-year ice and about 80 to 120 m for multi-year ice). This statistical relationship highlights that the snow cover reduces the overall topography of the ice cover. Besides this, there is prevalent positive covariability between snow depth and snow freeboard across a wide range of spatial scales. The variability and consistency analysis calls for more process-oriented observations and modeling activities to elucidate key processes governing snow–ice interaction and sea ice variability on various spatial scales. The statistical results can also be utilized in improving both radar and laser altimetry as well as the validation of sea ice and snow prognostic models.

Arctic ice in cross-disciplinary undergraduate education: Experiences across natural science, social science, international policy, and public writing

2020 ◽  
Author(s):  
Michelle Koutnik ◽  
Nadine Fabbi ◽  
Elizabeth Wessells ◽  
Ellen Ahlness ◽  
Max Showalter ◽  
...  
Keyword(s):  
Sea Ice ◽  
Undergraduate Education ◽  
Greenland Ice Sheet ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
International Policy ◽  
Public Writing ◽  
Arctic Sea ◽  
Arctic Ice ◽  
The University

&lt;p&gt;With the Arctic currently warming at a rate at least twice that of the global average, the coupled Arctic ecosystem is losing ice. This includes significant land-ice loss from the Greenland Ice Sheet and Arctic ice caps and glaciers, reduction in extent and thickness of Arctic sea ice, and thawing permafrost. This scale of environmental change significantly affects Arctic people, wildlife, infrastructure, transportation, and access. Societal response to these changes relies on advances in and application of research spanning multiple scientific disciplines, with policy-making done in partnership with Indigenous people, governments, private agencies, multinational corporations, and other interested groups. Everyone will interface with outcomes due to a changing climate and the challenge is mounting for the next generation of leaders. The cross-disciplinary nature of the challenge of Arctic ice loss and climate change must be met by cross-disciplinary undergraduate education. While higher education aims for disciplinary training in natural sciences and social sciences, there is an increasing responsibility to integrate topics and immerse students in real-world issues. And, in our experience the undergraduates we teach are eager for courses that can do this well.&lt;/p&gt;&lt;p&gt;What is immersive undergraduate education? We consider this as either immersing students in a focused topic in the classroom, immersing students in a place (especially while abroad), or combining the two through targeted lectures, informed discussions, travel, and writing. With regard to the Arctic, it is necessary to bring scientific understanding to learning activities otherwise focused on societal impacts, policy making, and knowledge exchange through public writing.&lt;/p&gt;&lt;p&gt;We share from our practical experience teaching Arctic-focused courses to classes each with 10-30 students with majors from across the University of Washington (UW) campus (total undergraduate student body of 32,000). Three recent activities that integrate the state of science with impacts on society in undergraduate courses include: 1) a four-week study abroad course to Greenland and Denmark focusing on changes in the Greenland Ice Sheet and sea-level rise, 2) a 10-week Task Force course in Arctic Sea Ice and International Policy in partnership with the UW International Policy Institute at the Henry M. Jackson School of International Studies that includes one-week in Ottawa where students develop a mock Arctic sea ice policy for Canada consistent with Inuit priorities, and 3) a 10-week seminar in public writing where students write mock newspaper articles, book reviews, and policy summaries about ice in a changing climate. These courses were designed to include a similar subset of earth science, atmospheric science, and oceanography, but the distinct structure and application of the science in these three separate courses led to distinct learning outcomes. In addition, we present how the academic minor in Arctic Studies at the University of Washington has allowed students to design their own integrated understanding of Indigenous and nation-state Arctic geopolitics, Arctic environmental change, and policy by taking a selection of courses and engaging in research and report writing.&lt;/p&gt;

Recent behavior of the Nares Strait ice arches: anomalous collapses and enhanced export of multi-year ice from the Arctic Ocean

2020 ◽  
Author(s):  
Kent Moore ◽  
Stephen Howell ◽  
Mike Brady ◽  
Xiaoyong Xu ◽  
Kaitlin McNeil
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
The Arctic ◽  
Nares Strait ◽  
Short Period ◽  
The Arctic Ocean ◽  
Arctic Ice ◽  
Policy Communities ◽  
Ice Pack ◽  
Area And Volume

&lt;p&gt;The ice arches that usually develop at the northern and southern ends of Nares Strait play an important role in modulating the export of multi-year sea ice out of the Arctic Ocean.&amp;#160;&amp;#160; As a result of global warming, the Arctic Ocean is evolving towards an ice pack that is younger, thinner and more mobile and the fate of its multi-year ice is becoming of increasing interest to both the scientific and policy communities.&amp;#160; Here, we use sea ice motion retrievals derived from Sentinel-1 imagery to report on recent behaviour of these ice arches and the associated ice flux. In addition to the previously identified early collapse of the northern ice arch in May 2017, we report that this arch failed to develop during the winters of 2018 and 2019.&amp;#160; In contrast, we report that the southern ice arch was only present for a short period of time during the winter of 2018.&amp;#160; We also show that the duration of arch formation has decreased over the past 20 years as ice in the region has thinned, while the ice area and volume fluxes have both increased.&amp;#160; These results suggest that a transition is underway towards a state where the formation of these arches will become atypical with a concomitant increase in the export of multi-year ice accelerating the transition towards a younger and thinner Arctic ice pack.&lt;/p&gt;

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