Seasonal and long term evolution of oceanographic conditions based on year-around observation in Kongsfjorden, Arctic Ocean

Noufal, K. K.; Najeem, S.; Latha, G.; Venkatesan, R.

doi:10.1016/j.polar.2016.11.001

Cited by 14 publications

(6 citation statements)

References 34 publications

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“…The strength of stratification is usually characterized by buoyancy frequency, N , with N up to 0.02 s −1 characteristic for the ocean and seas 9 , 10 . Higher buoyancy frequency was reported for fiords 11 – 13 with the maximum N ranging from 0.1 s −1 to 0.3 s −1 and hypersaline lakes, e.g. N up to 0.12 s −1 for Mono Lake, California 14 and N ~ 0.17 s −1 for the Dead Sea 15 .…”

Section: Introductionmentioning

confidence: 79%

Stratification-induced reorientation of disk settling through ambient density transition

Mrokowska

2018

Sci Rep

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Settling due to gravity force is a basic transport mechanism of solid particles in fluids in the Earth. A large portion of particles occurring in nature and used in technical applications are non-spherical. Settling of particles is usually studied in homogeneous ambient conditions, however, stratification is inherent of natural fluids. It has been acknowledged that stratification modifies the velocity of settling spheres and amorphous aggregates. However, the effect of particle shape on the dynamics of settling through density-stratified ambient fluid has not been recognized well enough. Here I show experimental evidence that continuous density transition markedly modifies the settling dynamics of a disk in terms of settling velocity and orientation of a particle. Settling dynamics of a disk are more complex than dynamics of spheres and aggregates studied previously. I found that in a two-layer ambient with density transition, a disk settling in a low Reynolds number regime undergoes five phases of settling with the orientation varying from horizontal to vertical, and it may achieve two local minimum settling velocities in the density transition layer. Moreover, I found that the settling dynamics depends on a density difference between upper and lower homogeneous layers, stratification strength and thickness of density transition.

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Section: Introductionmentioning

confidence: 79%

Stratification-induced reorientation of disk settling through ambient density transition

Mrokowska

2018

Sci Rep

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“…2 used a single figure for multiple, averaged water temperatures between 20 m and 60 m depth. Differences in temperature with depth may be significant, and likely to be more pronounced during summer when the fjords are more stratified as a result of freshwater influx 30 . For this reason, an array of temperature sensors at different depths is preferable and should be implemented where possible.…”

Section: Discussionmentioning

confidence: 99%

Relating ocean temperatures to frontal ablation rates at Svalbard tidewater glaciers: Insights from glacier proximal datasets

Holmes

Kirchner

Kuttenkeuler

et al. 2019

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Fjord-terminating glaciers in Svalbard lose mass through submarine melt and calving (collectively: frontal ablation), and surface melt. With the recently observed Atlantification of water masses in the Barents Sea, warmer waters enter these fjords and may reach glacier fronts, where their role in accelerating frontal ablation remains insufficiently understood. Here, the impact of ocean temperatures on frontal ablation at two glaciers is assessed using time series of water temperature at depth, analysed alongside meteorological and glaciological variables. Ocean temperatures at depth are harvested at distances of 1 km from the calving fronts of the glaciers Kronebreen and Tunabreen, western Svalbard, from 2016 to 2017. We find ocean temperature at depth to control c. 50% of frontal ablation, making it the most important factor. However, its absolute importance is considerably less than found by a 2013–2014 study, where temperatures were sampled much further away from the glaciers. In light of evidence that accelerating levels of global mass loss from marine terminating glaciers are being driven by frontal ablation, our findings illustrate the importance of sampling calving front proximal water masses.

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“…The Kongsfjorden ecosystem undergoes strong seasonal and inter-annual changes in biota functioning due to changes in hydrography, driven by impact of the West Spitsbergen Current (WSC), melting of snow and glaciers, local climate features, and global climate changes (e.g., Cottier et al 2005;Wiencke and Hop 2016;Noufal et al 2017). These processes are key ecological regulators as they determine timing of the spring bloom, taxonomic composition of pelagic communities, or biogenic matter fluxes (e.g., Hop et al 2006;Hegseth and Tverberg 2013;Lalande et al 2016).…”

Section: Study Areamentioning

confidence: 99%

“…Inflows along the bottom allow for the convection and mixing, enhancing the bloom, while surface inflows can hinder water mixing and delay the bloom (Hegseth and Tverberg 2013). In summer, as a result of river runoff, precipitation, and glacier melting, a surface layer of less saline 1 3 waters forms, which together with a strong subsurface intrusion of warm and more saline Atlantic waters causes strong stratification of the water column (Noufal et al 2017). In winter, as a consequence of water cooling, the whole water column is well mixed (Noufal et al 2017).…”

Section: Study Areamentioning

confidence: 99%

“…In summer, as a result of river runoff, precipitation, and glacier melting, a surface layer of less saline 1 3 waters forms, which together with a strong subsurface intrusion of warm and more saline Atlantic waters causes strong stratification of the water column (Noufal et al 2017). In winter, as a consequence of water cooling, the whole water column is well mixed (Noufal et al 2017). During this time the biological activity of both autotrophs and zooplankton in the water column is very low, resulting in low organic matter fluxes to the sea bottom (Lalande et al 2016).…”

Section: Study Areamentioning

confidence: 99%

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Seasonal constancy (summer vs. winter) of benthic size spectra in an Arctic fjord

et al. 2019

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Size spectra are important descriptors of community structure and can indicate changes in community functioning in response to shifts in environmental conditions. There are relatively few assessments of benthic size spectra, and most are based on summer samples alone. Processes influencing size spectra, such as recruitment and predation pressure, vary seasonally, and understanding this variation is necessary to interpret patterns in time or space. Here we compare summer and winter biomass size spectra in the central basin of Kongsfjorden (west Spitsbergen). We recorded seasonal changes in the quality of organic matter available to the benthos, indicated by higher chloroplastic pigments concentrations in surface sediments in summer, as well as in differences in total abundance and biomass of both macrofauna and meiofauna. No significant seasonal differences were documented by multiple regression models for the normalized biomass and size classes. The slope of a linear relationship between normalized biomass and size classes was − 0.54 ± 0.02 indicating a productive system, compared to ecosystems like estuaries. Summer-winter invariability of size spectra suggests that benthic community functioning in this Arctic fjordic system is relatively independent from the seasonality in the supply of organic matter produced in water column.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Seasonal and long term evolution of oceanographic conditions based on year-around observation in Kongsfjorden, Arctic Ocean

Cited by 14 publications

References 34 publications

Stratification-induced reorientation of disk settling through ambient density transition

Stratification-induced reorientation of disk settling through ambient density transition

Relating ocean temperatures to frontal ablation rates at Svalbard tidewater glaciers: Insights from glacier proximal datasets

Seasonal constancy (summer vs. winter) of benthic size spectra in an Arctic fjord

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