scholarly journals Annual survival probabilities of anadromous Arctic Char remain high and stable despite inter-annual differences in sea ice melt date

2021 ◽  
Author(s):  
Isabeau Caza-Allard ◽  
Marc J. Mazerolle ◽  
Les N Harris ◽  
Brendan Malley ◽  
Ross F. Tallman ◽  
...  
Keyword(s):  
Sea Ice ◽  
Survival Probability ◽  
Interannual Variation ◽  
Salvelinus Alpinus ◽  
Ice Cover ◽  
Arctic Char ◽  
Annual Survival ◽  
Survival Probabilities ◽  
Ice Melt ◽  
The Impact

Throughout their range, anadromous Arctic Char (Salvelinus alpinus) support commercial, recreational, and subsistence fisheries that are important economically, socially, and culturally yet drivers of interannual variation in survival in this species, however, remain poorly understood. Here, we aimed to quantify the impact of environmental and biological parameters on the survival probability of anadromous Arctic Char near the community of Cambridge Bay, Nunavut. To do so, we tracked 183 Arctic Char tagged with acoustic transmitters and used capture-mark-recapture methods to estimate survival probabilities over six years. Annual survival probabilities for individuals was high, varying between 0.79 and 0.88, whereas recapture probabilities varied between 0.64 and 0.90. Interannual variation in survival probability was low and neither the environmental (air temperature, sea ice cover) nor biological (sex) variables influenced survival probability. These estimates suggest that annual survival probability is high for anadromous adult Arctic Char in the Cambridge Bay area, despite clear differences in the ice cover melt date among years. These results further our understanding of the demographic parameters of Arctic Char in the region, which will be important for future assessments of the sustainability of commercial fisheries as well as for predicting population responses to a rapidly changing Arctic.

scholarly journals The Impact of Regional Arctic Sea Ice Loss on Atmospheric Circulation and the NAO

2016 ◽  
Vol 29 (2) ◽  
pp. 889-902 ◽  
Author(s):  
Rasmus A. Pedersen ◽  
Ivana Cvijanovic ◽  
Peter L. Langen ◽  
Bo M. Vinther
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
General Circulation ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Near Surface ◽  
Arctic Sea ◽  
The Impact ◽  
Sea Ice Reduction

Abstract Reduction of the Arctic sea ice cover can affect the atmospheric circulation and thus impact the climate beyond the Arctic. The atmospheric response may, however, vary with the geographical location of sea ice loss. The atmospheric sensitivity to the location of sea ice loss is studied using a general circulation model in a configuration that allows combination of a prescribed sea ice cover and an active mixed layer ocean. This hybrid setup makes it possible to simulate the isolated impact of sea ice loss and provides a more complete response compared to experiments with fixed sea surface temperatures. Three investigated sea ice scenarios with ice loss in different regions all exhibit substantial near-surface warming, which peaks over the area of ice loss. The maximum warming is found during winter, delayed compared to the maximum sea ice reduction. The wintertime response of the midlatitude atmospheric circulation shows a nonuniform sensitivity to the location of sea ice reduction. While all three scenarios exhibit decreased zonal winds related to high-latitude geopotential height increases, the magnitudes and locations of the anomalies vary between the simulations. Investigation of the North Atlantic Oscillation reveals a high sensitivity to the location of the ice loss. The northern center of action exhibits clear shifts in response to the different sea ice reductions. Sea ice loss in the Atlantic and Pacific sectors of the Arctic cause westward and eastward shifts, respectively.

scholarly journals Pack-Ice Motion in the Weddell Sea in Relation to Weather Systems and Determination of a Weddell Sea Sea-Ice Budget

1989 ◽  
Vol 12 ◽  
pp. 104-112 ◽  
Author(s):  
D.W.S. Limbert ◽  
S.J. Morrison ◽  
C.B. Sear ◽  
P. Wadhams ◽  
M.A. Rowe
Keyword(s):  
Sea Ice ◽  
Surface Pressure ◽  
Ice Cover ◽  
Weddell Sea ◽  
Air Pressure ◽  
Ice Formation ◽  
Pack Ice ◽  
The Impact

As part of the Winter Weddell Sea Project 1986 (WWSP 86), a buoy, transmitting via TIROS-N satellites to Service Argos, was inserted into an ice floe in the southern Weddell Sea. Operational U.K. Meteorological Office numerical surface-pressure analyses, which utilized the buoy’s measured values of air pressure and temperature, are used to assess the impact of weather systems on pack-ice movement. The motion of the buoy is shown to be related closely to the position of the circumpolar trough and to the tracks of depressions crossing the area. The tracks of this and other buoys deployed during WWSP 86 are analysed, together with the known drifts of some ice-bound vessels, to establish the overall movement of sea ice in the central and western Weddell Sea. Using these data, the area of ice transported northward out of the Weddell Sea is determined. Roughly 60% of the winter sea-ice cover is discharged out of the area, and is replaced by new ice formation in coastal polynyas and by influx of new ice from the east. In summer, a further 30% is discharged northward out of the region, leaving 40% cover and by implication a 30% loss by melting.

scholarly journals Phytoplankton distribution in unusually low sea ice cover over the Pacific Arctic

2012 ◽  
Vol 9 (11) ◽  
pp. 4835-4850 ◽  
Author(s):  
P. Coupel ◽  
H. Y. Jin ◽  
M. Joo ◽  
R. Horner ◽  
H. A. Bouvet ◽  
...  
Keyword(s):  
Sea Ice ◽  
Marine Ecosystem ◽  
Environmental Parameters ◽  
Arctic Basin ◽  
Ice Cover ◽  
Phytoplankton Distribution ◽  
The Pacific ◽  
Ice Retreat ◽  
Sea Ice Retreat ◽  
The Impact

Abstract. A large part of the Pacific Arctic basin experiences ice-free conditions in summer as a result of sea ice cover steadily decreasing over the last decades. To evaluate the impact of sea ice retreat on the marine ecosystem, phytoplankton in situ observations were acquired over the Chukchi shelf and the Canadian basin in 2008, a year of high melting. Pigment analyses and taxonomy enumerations were used to characterise the distribution of main phytoplanktonic groups. Marked spatial variability of the phytoplankton distribution was observed in summer 2008. Comparison of eight phytoplankton functional groups and 3 size-classes (pico-, nano- and micro-phytoplankton) also showed significant differences in abundance, biomass and distribution between summer of low ice cover (2008) and heavy ice summer (1994). Environmental parameters such as freshening, stratification, light and nutrient availability are discussed as possible causes to explain the observed differences in phytoplankton community structure between 1994 and 2008.

scholarly journals Impact of a warm anomaly in the Pacific Arctic region derived from time-series export fluxes

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255837
Author(s):  
Catherine Lalande ◽  
Jacqueline M. Grebmeier ◽  
Andrew M. P. McDonnell ◽  
Russell R. Hopcroft ◽  
Stephanie O’Daly ◽  
...  
Keyword(s):  
Sea Ice ◽  
Bering Sea ◽  
Chukchi Sea ◽  
Arctic Region ◽  
Ice Cover ◽  
Biological Pump ◽  
Northern Bering Sea ◽  
Pacific Waters ◽  
The Pacific ◽  
The Impact

Unusually warm conditions recently observed in the Pacific Arctic region included a dramatic loss of sea ice cover and an enhanced inflow of warmer Pacific-derived waters. Moored sediment traps deployed at three biological hotspots of the Distributed Biological Observatory (DBO) during this anomalously warm period collected sinking particles nearly continuously from June 2017 to July 2019 in the northern Bering Sea (DBO2) and in the southern Chukchi Sea (DBO3), and from August 2018 to July 2019 in the northern Chukchi Sea (DBO4). Fluxes of living algal cells, chlorophyll a (chl a), total particulate matter (TPM), particulate organic carbon (POC), and zooplankton fecal pellets, along with zooplankton and meroplankton collected in the traps, were used to evaluate spatial and temporal variations in the development and composition of the phytoplankton and zooplankton communities in relation to sea ice cover and water temperature. The unprecedented sea ice loss of 2018 in the northern Bering Sea led to the export of a large bloom dominated by the exclusively pelagic diatoms Chaetoceros spp. at DBO2. Despite this intense bloom, early sea ice breakup resulted in shorter periods of enhanced chl a and diatom fluxes at all DBO sites, suggesting a weaker biological pump under reduced ice cover in the Pacific Arctic region, while the coincident increase or decrease in TPM and POC fluxes likely reflected variations in resuspension events. Meanwhile, the highest transport of warm Pacific waters during 2017–2018 led to a dominance of the small copepods Pseudocalanus at all sites. Whereas the export of ice-associated diatoms during 2019 suggested a return to more typical conditions in the northern Bering Sea, the impact on copepods persisted under the continuously enhanced transport of warm Pacific waters. Regardless, the biological pump remained strong on the shallow Pacific Arctic shelves.

scholarly journals The impact of melt ponds on summertime microwave brightness temperatures and sea ice concentrations

2016 ◽  
Author(s):  
S. Kern ◽  
A. Rösel ◽  
L. T. Pedersen ◽  
N. Ivanova ◽  
R. Saldo ◽  
...  
Keyword(s):  
Sea Ice ◽  
Open Water ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Water Fraction ◽  
Microwave Brightness Temperature ◽  
Ice Melt ◽  
Melt Ponds ◽  
Retrieval Algorithms ◽  
The Impact

Abstract. The sea ice concentration (SIC) derived from satellite microwave brightness temperature (TB) data are known to be less accurate during summer melt conditions – in the Arctic Ocean primarily because of the impact of melt ponds on sea ice. Using data from June to August 2009, we investigate how TBs and SICs vary as a function of the ice surface fraction (ISF) computed from open water fraction and melt pond fraction both derived from satellite optical reflectance data. SIC is computed from TBs using a set of eight different retrieval algorithms and applying a consistent set of tie points. We find that TB values change during sea ice melt non-linearly and not monotonically as a function of ISF for ISF of 50 to 100 %. For derived parameters such as the polarization ratio at 19 GHz the change is monotonic but substantially smaller than theoretically expected. Changes in ice/snow radiometric properties during melt also contribute to the TB changes observed; these contributions are functions of frequency and polarization and have the potential to partly counter-balance the impact of changing ISF on the observed TBs. All investigated SIC retrieval algorithms overestimate ISF when using winter tie points. The overestimation varies among the algorithms as a function of ISF such that the SIC retrieval algorithms could be categorized into two different classes. These reveal a different degree of ISF overestimation at high ISF and an opposite development of ISF over-estimation as ISF decreases. For one class, correlations between SIC and ISF are ≥ 0.85 and the associated linear regression lines suggest an exploitable relationship between SIC and ISF if reliable summer sea ice tie points can be established. This study shows that melt ponds are interpreted as open water by the SIC algorithms, while the concentration of ice between the melt ponds is in general being overestimated. These two effects may cancel each other out and thus produce seemingly correct SIC for the wrong reasons. This cancelling effect will in general only be "correct" at one specific value of MPF. Based on our findings we recommend to not correct SIC algorithms for the impact of melt ponds as this seems to violate physical principles. Users should be aware that the SIC algorithms available at the moment retrieve a combined parameter presented by SIC in winter and ISF in summer.

scholarly journals Underestimation of surface pCO2 and air-sea CO2 fluxes due to freshwater stratification in an Arctic shelf sea, Hudson Bay

Elem Sci Anth ◽  
2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohamed M. M. Ahmed ◽  
Brent G. T. Else ◽  
David Capelle ◽  
Lisa A. Miller ◽  
Tim Papakyriakou
Keyword(s):  
Sea Ice ◽  
River Runoff ◽  
Dissolved Inorganic Carbon ◽  
Stable Isotope Ratio ◽  
Total Alkalinity ◽  
Hudson Bay ◽  
Co2 Fluxes ◽  
Ancillary Data ◽  
Ice Melt ◽  
The Impact

The objective of this study is to quantify the impact of freshwater stratification on the vertical gradients of partial pressure of CO2 (pCO2) and estimates of air-sea CO2 exchange in Hudson Bay during peak sea-ice melt and river runoff. During the spring of 2018, we sampled water in Hudson Bay and Hudson Strait for dissolved inorganic carbon, total alkalinity, salinity, the oxygen stable isotope ratio in the water (δ18O), and other ancillary data. The coastal domain and regions close to the ice edge had significant vertical concentration gradients of pCO2 across the top meters of the ocean due to the presence of a stratified fresh layer at the surface. The pCO2 and salinity in the central (where sea-ice melt was significant) and the southeast (where river runoff and sea-ice melt were significant) side of the bay generally increased with depth, with average gradients of 4.5 μatm m–1 and 0.5 m–1, respectively. Ignoring these gradients causes a significant error in calculating air-sea CO2 fluxes, especially when using shipboard underway systems that measure pCO2 at several meters below the sea surface. We found that the oceanic CO2 sink in Hudson Bay is underestimated by approximately 50% if underway pCO2 system measurements are used without correction. However, we observed that these gradients do not persist for more than 5 weeks following ice melt. We have derived a linear correction for underway pCO2 measurements to account for freshwater stratification during periods of 1–5 weeks after ice breakup. Given the lack of measurements in stratified Arctic waters, our results provide a road map to better estimates of the important role of these regions in global carbon cycles.

scholarly journals Pack-Ice Motion in the Weddell Sea in Relation to Weather Systems and Determination of a Weddell Sea Sea-Ice Budget

1989 ◽  
Vol 12 ◽  
pp. 104-112 ◽  
Author(s):  
D.W.S. Limbert ◽  
S.J. Morrison ◽  
C.B. Sear ◽  
P. Wadhams ◽  
M.A. Rowe
Keyword(s):  
Sea Ice ◽  
Surface Pressure ◽  
Ice Cover ◽  
Weddell Sea ◽  
Air Pressure ◽  
Ice Formation ◽  
Pack Ice ◽  
The Impact

As part of the Winter Weddell Sea Project 1986 (WWSP 86), a buoy, transmitting via TIROS-N satellites to Service Argos, was inserted into an ice floe in the southern Weddell Sea. Operational U.K. Meteorological Office numerical surface-pressure analyses, which utilized the buoy’s measured values of air pressure and temperature, are used to assess the impact of weather systems on pack-ice movement. The motion of the buoy is shown to be related closely to the position of the circumpolar trough and to the tracks of depressions crossing the area. The tracks of this and other buoys deployed during WWSP 86 are analysed, together with the known drifts of some ice-bound vessels, to establish the overall movement of sea ice in the central and western Weddell Sea. Using these data, the area of ice transported northward out of the Weddell Sea is determined. Roughly 60% of the winter sea-ice cover is discharged out of the area, and is replaced by new ice formation in coastal polynyas and by influx of new ice from the east. In summer, a further 30% is discharged northward out of the region, leaving 40% cover and by implication a 30% loss by melting.

scholarly journals An enhancement to sea ice motion and age products

2019 ◽  
Author(s):  
Mark A. Tschudi ◽  
Walter N. Meier ◽  
J. Scott Stewart
Keyword(s):  
Sea Ice ◽  
Ice Cover ◽  
The Arctic ◽  
Significant Shift ◽  
High Concentration ◽  
Sea Ice Extent ◽  
Previous Version ◽  
Arctic Ice ◽  
The Impact ◽  
Snow And Ice

Abstract. A new version of the sea ice motion and age products distributed at the National Snow and Ice Data Center's NASA Snow and Ice Distributed Active Archive Center has been developed. The new version, 4.0, includes several significant upgrades in processing, corrects known issues with the previous version, and updates the time series through 2018, with regular updates planned for the future. Here, we provide a history of the product development, discuss the improvements to the algorithms that create these products, and compare the Version 4 products to the previous version. While Version 4 algorithm changes were significant, the impact on the products is relatively minor, particularly for more recent years. Trends in motion and age are not substantially different between the versions. Changes in sea ice motion and age derived from the product show a significant shift in the Arctic ice cover, from a pack with a high concentration of older ice, to a sea ice cover dominated by first-year ice, which is more susceptible to summer melt. We also observe an increase in the speed of the ice in recent years, which is anticipated with the annual decrease in sea ice extent.

scholarly journals Signature of ice melt over the Greenland derived from MSMR (OCEANSAT-1) data

MAUSAM ◽  
2021 ◽  
Vol 62 (4) ◽  
pp. 627-632
Author(s):  
N. SHARMA ◽  
M.K. DASH ◽  
N.K. VYAS ◽  
S.M. BHANDARI ◽  
P.C. PANDEY ◽  
...  
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
Climate Changes ◽  
Ice Sheets ◽  
Polar Regions ◽  
Ice Melt ◽  
Continental Ice Sheets ◽  
The Antarctic ◽  
The Impact ◽  
Concentration Levels

In order to monitor the impact of global warming phenomena over the Polar Regions, it is necessary to monitor snow/ice melt on the Greenland and the Antarctic ice sheets. Using MSMR data, it is possible to differentiate sea ice at different concentration levels. On the basis of microwave emissivities of continental ice and sea ice, useful information on the formation and melting of the ice can be derived. The paper discusses different strategies to derive a melt signal from the MSMR observations for the continental ice sheets in Greenland. The Polarization Difference (PD) for 21 GHz, available from MSMR data, is studied and an appropriate threshold is selected to detect the presence of melt signal. The results of the present study have bearing on climate changes.

scholarly journals Temporal evolution of IP25 and other highly branched isoprenoid lipids in sea ice and the underlying water column during an Arctic melting season

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Rémi Amiraux ◽  
Lukas Smik ◽  
Denizcan Köseoğlu ◽  
Jean-François Rontani ◽  
Virginie Galindo ◽  
...  
Keyword(s):  
Sea Ice ◽  
Water Column ◽  
Spring Bloom ◽  
Phytoplankton Bloom ◽  
Change Point Analysis ◽  
The Arctic ◽  
Distribution Data ◽  
Ice Melt ◽  
Point Analysis ◽  
The Impact

In recent years, certain mono- and di-unsaturated highly branched isoprenoid (HBI) alkene biomarkers (i.e., IP25 and HBI IIa) have emerged as useful proxies for sea ice in the Arctic and Antarctic, respectively. Despite the relatively large number of sea ice reconstructions based on IP25 and HBI IIa, considerably fewer studies have addressed HBI variability in sea ice or in the underlying water column during a spring bloom and ice melt season. In this study, we quantified IP25 and various other HBIs at high temporal and vertical resolution in sea ice and the underlying water column (suspended and sinking particulate organic matter) during a spring bloom/ice melt event in Baffin Bay (Canadian Arctic) as part of the Green Edge project. The IP25 data are largely consistent with those reported from some previous studies, but also highlight: (i) the short-term variability in its production in sea ice; (ii) the release of ice algae with high sinking rates following a switch in sea ice conditions from hyper- to hyposaline within the study period; and (iii) the occurrence of an under-ice phytoplankton bloom. Outcomes from change-point analysis conducted on chlorophyll a and IP25, together with estimates of the percentage of ice algal organic carbon in the water column, also support some previous investigations. The co-occurrence of other di- and tri-unsaturated HBIs (including the pelagic biomarker HBI III) in sea ice are likely to have originated from the diatom Berkeleya rutilans and/or the Pleurosigma and Rhizosolenia genera, residing either within the sea ice matrix or on its underside. Although a possible sea ice source for HBIs such as HBI III may also impact the use of such HBIs as pelagic counterparts to IP25 in the phytoplankton marker-IP25 index, we suggest that the impact is likely to be small based on HBI distribution data.

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