scholarly journals On the potential contribution of open lead particle emissions to the central Arctic aerosol concentration

2010 ◽  
Vol 10 (10) ◽  
pp. 24961-24992 ◽  
Author(s):  
A. Held ◽  
I. M. Brooks ◽  
C. Leck ◽  
M. Tjernström
Keyword(s):  
Particle Deposition ◽  
Particle Number ◽  
Mixing Layer ◽  
Open Water ◽  
Potential Contribution ◽  
Central Arctic Ocean ◽  
Lead Particle ◽  
Ocean Study ◽  
Number Variation ◽  
Atmospheric Variations

Abstract. During the ice-breaker borne ASCOS expedition (Arctic Summer Cloud Ocean Study) direct eddy covariance measurements of aerosol number fluxes were carried out in August 2008 on the edge of an ice floe drifting in the central Arctic Ocean between 2°–10° W longitude and 87°–87.5° N latitude. The median aerosol transfer velocities over different surface types (open water leads, ice ridges, snow and ice surfaces) ranged from 0.27 to 0.68 mm s−1 during deposition-dominated episodes. Emission periods were observed more frequently over the open lead, while the snow behaved primarily as a deposition surface. Directly measured aerosol fluxes were compared with particle deposition parameterizations in order to estimate the emission flux from the observed net aerosol flux. Finally, the contribution of the open lead particle source to atmospheric variations in particle number concentration was evaluated and compared with the observed temporal evolution of particle number. The direct emission of aerosol particles from the open lead can only explain 5–10% of the observed particle number variation in the mixing layer close to the surface.

scholarly journals On the potential contribution of open lead particle emissions to the central Arctic aerosol concentration

2011 ◽  
Vol 11 (7) ◽  
pp. 3093-3105 ◽  
Author(s):  
A. Held ◽  
I. M. Brooks ◽  
C. Leck ◽  
M. Tjernström
Keyword(s):  
Particle Deposition ◽  
Particle Number ◽  
Mixing Layer ◽  
Open Water ◽  
Potential Contribution ◽  
Central Arctic Ocean ◽  
Lead Particle ◽  
Ocean Study ◽  
Number Variation ◽  
Atmospheric Variations

Abstract. We present direct eddy covariance measurements of aerosol number fluxes, dominated by sub-50 nm particles, at the edge of an ice floe drifting in the central Arctic Ocean. The measurements were made during the ice-breaker borne ASCOS (Arctic Summer Cloud Ocean Study) expedition in August 2008 between 2°–10° W longitude and 87°–87.5° N latitude. The median aerosol transfer velocities over different surface types (open water leads, ice ridges, snow and ice surfaces) ranged from 0.27 to 0.68 mm s−1 during deposition-dominated episodes. Emission periods were observed more frequently over the open lead, while the snow behaved primarily as a deposition surface. Directly measured aerosol fluxes were compared with particle deposition parameterizations in order to estimate the emission flux from the observed net aerosol flux. Finally, the contribution of the open lead particle source to atmospheric variations in particle number concentration was evaluated and compared with the observed temporal evolution of particle number. The direct emission of aerosol particles from the open lead can explain only 5–10% of the observed particle number variation in the mixing layer close to the surface.

Particle Deposition in a Room-Scale Chamber With Particle Injection

2005 ◽  
Author(s):  
N. Zhang ◽  
Z. Charlie Zheng ◽  
L. Glasgow ◽  
B. Braley
Keyword(s):  
Particle Deposition ◽  
Particle Number ◽  
Particle Distribution ◽  
Turbulent Transport ◽  
Distribution Patterns ◽  
Particle Number Density ◽  
Number Density ◽  
Small Particles ◽  
Particle Injection ◽  
Simulation Results

A model simulating the deposition of small particles with turbulent transport, sedimentation, and coagulation, is presented. Experimental measurements were conducted in a room-scale chamber using a specially designed sequential sampler. The measured deposition-rate data are compared with the simulation results. Distributions of particle-number density at different times are plotted in several viewing planes to facilitate discussion of the particle distribution patterns.

Particulates of the surface microlayer of open water in the central Arctic Ocean in summer

2004 ◽  
Vol 91 (1-4) ◽  
pp. 131-141 ◽  
Author(s):  
E. Keith Bigg ◽  
Caroline Leck ◽  
Lars Tranvik
Keyword(s):  
Arctic Ocean ◽  
Open Water ◽  
Surface Microlayer ◽  
Central Arctic Ocean

scholarly journals Fisheries Enforcement on the High Seas of the Arctic Ocean: Gaps, Solutions and the Potential Contribution of the European Union and Its Member States

2018 ◽  
Vol 33 (2) ◽  
pp. 324-360 ◽  
Author(s):  
Efthymios Papastavridis
Keyword(s):  
Arctic Ocean ◽  
The Arctic ◽  
Commercial Fishing ◽  
Potential Contribution ◽  
The European Union ◽  
Fishing Activity ◽  
Central Arctic Ocean ◽  
The North ◽  
Opening Up ◽  
High Seas

Abstract Although there is no fishing activity within the central Arctic Ocean at present, commercial fishing activity does occur in the high seas areas of the North Atlantic and North Pacific, and within the exclusive economic zone of the Arctic coastal States. Climate change will most probably lead to an increase in fishing activity, through the reduction in sea ice, opening up new areas of the Arctic to fisheries, including the Central Arctic Ocean. This prospect has fuelled intensive negotiations—still ongoing—for the signing of a legally binding agreement to prevent unregulated fisheries therein. What seems missing, though, from both the ongoing negotiations on this agreement and the scholarly literature is reference to fisheries enforcement in the Arctic. Accordingly, this article identifies the most effective tools that could be employed for fisheries enforcement purposes, including port and flag State measures, and addresses their potential application in the Arctic.

scholarly journals Fisheries Enforcement on the High Seas of the Arctic Ocean: Gaps, Solutions and the Potential Contribution of the European Union and its Member States

2018 ◽  
Author(s):  
Efthymios Papastavridis
Keyword(s):  
Arctic Ocean ◽  
The Arctic ◽  
Commercial Fishing ◽  
Potential Contribution ◽  
The European Union ◽  
Fishing Activity ◽  
Central Arctic Ocean ◽  
The North ◽  
Opening Up ◽  
High Seas

Although there is no fishing activity within the central Arctic Ocean at present, commercial fishing activity does occur in the high seas areas of the North Atlantic and North Pacific, and within the exclusive economic zone of the Arctic coastal States. Climate change will most probably lead to an increase in fishing activity, through the reduction in sea ice, opening up new areas of the Arctic to fisheries, including the Central Arctic Ocean. This prospect has fuelled intensive negotiations - still ongoing - for the signing of a legally binding agreement to prevent unregulated fisheries therein. What seems missing, though, from both the ongoing negotiations on this agreement and the scholarly literature is reference to fisheries enforcement in the Arctic. Accordingly, this article identifies the most effective tools that could be employed for fisheries enforcement purposes, including port and flag State measures, and addresses their potential application in the Arctic.

scholarly journals Aerosol composition and sources in the central Arctic Ocean during ASCOS

2011 ◽  
Vol 11 (20) ◽  
pp. 10619-10636 ◽  
Author(s):  
R. Y.-W. Chang ◽  
C. Leck ◽  
M. Graus ◽  
M. Müller ◽  
J. Paatero ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
The Arctic ◽  
Aerosol Composition ◽  
Central Arctic Ocean ◽  
Entire Study ◽  
Ambient Aerosol ◽  
Mass Spectral ◽  
Aerosol Mass ◽  
Organic Factor ◽  
Ocean Study

Abstract. Measurements of submicron aerosol chemical composition were made over the central Arctic Ocean from 5 August to 8 September 2008 as a part of the Arctic Summer Cloud Ocean Study (ASCOS) using an aerosol mass spectrometer (AMS). The median levels of sulphate and organics for the entire study were 0.051 and 0.055 μ g m−3, respectively. Positive matrix factorisation was performed on the entire mass spectral time series and this enabled marine biogenic and continental sources of particles to be separated. These factors accounted for 33% and 36% of the sampled ambient aerosol mass, respectively, and they were both predominantly composed of sulphate, with 47% of the sulphate apportioned to marine biogenic sources and 48% to continental sources, by mass. Within the marine biogenic factor, the ratio of methane sulphonate to sulphate was 0.25 ± 0.02, consistent with values reported in the literature. The organic component of the continental factor was more oxidised than that of the marine biogenic factor, suggesting that it had a longer photochemical lifetime than the organics in the marine biogenic factor. The remaining ambient aerosol mass was apportioned to an organic-rich factor that could have arisen from a combination of marine and continental sources. In particular, given that the factor does not correlate with common tracers of continental influence, we cannot rule out that the organic factor arises from a primary marine source.

Response of littoral macroinvertebrate communities on rocks and sediments to lake residential development

2008 ◽  
Vol 65 (6) ◽  
pp. 1206-1216 ◽  
Author(s):  
Simon De Sousa ◽  
Bernadette Pinel-Alloul ◽  
Antonia Cattaneo
Keyword(s):  
Particle Deposition ◽  
Size Structure ◽  
Open Water ◽  
Residential Development ◽  
Taxonomic Composition ◽  
Total Biomass ◽  
Macroinvertebrate Communities ◽  
Littoral Invertebrates ◽  
Woody Litter ◽  
The Impact

Previously pristine lakes of the Laurentian region of Quebec, Canada, have faced increasing residential development of their watershed since the 1970s. We tested whether littoral invertebrates respond to this perturbation, even though open-water nutrients and chlorophyll are not yet altered. We examined changes in biomass, size structure, and taxonomic composition of macroinvertebrates living on rocks and sediments in 13 lakes representing a gradient of lakeshore residential development and watershed clearing. Littoral invertebrates provided early indication of lake perturbation, but their response varied according to the substratum. On rocks, total invertebrate biomass increased along the perturbation gradient and size structure shifted towards large organisms. These changes were likely mediated by a concomitant increase in epilithon biomass, suggesting a bottom-up control. No significant change in total biomass and size structure was observed for invertebrates in sediments. In contrast, taxonomic composition changed with lake development in sediments, but not on rocks. Taxonomic shifts were likely related to changes in sediment heterogeneity due to a decline of woody litter and increased fine particle deposition. Oligochaetes were positively associated to perturbation, whereas mayflies were negatively associated; these taxa could be used as indicators. Sediments were a better sentinel substratum than rocks for biomonitoring the impact of lake residential development.

scholarly journals Near-surface profiles of aerosol number concentration and temperature over the Arctic Ocean

2011 ◽  
Vol 4 (3) ◽  
pp. 3017-3053 ◽  
Author(s):  
A. Held ◽  
D. A. Orsini ◽  
P. Vaattovaara ◽  
M. Tjernström ◽  
C. Leck
Keyword(s):  
Heat Flux ◽  
Arctic Ocean ◽  
Particle Deposition ◽  
Deposition Velocity ◽  
Sensible Heat Flux ◽  
Number Concentration ◽  
The Arctic ◽  
Sensible Heat ◽  
Central Arctic Ocean ◽  
Near Surface

Abstract. Temperature and particle number concentration profiles were measured at small height intervals above open and frozen leads and snow surfaces in the central Arctic. The device used was a gradient pole designed to investigate potential particle sources over the central Arctic Ocean. The collected data was fitted according to basic logarithmic flux-profile relationships to calculate the sensible heat flux and particle deposition velocity. Independent measurements by the eddy covariance technique were conducted at the same location. General agreement was observed between the two methods when logarithmic profiles could be fitted to the gradient pole data. In general, snow surfaces behaved as weak particle sinks with a maximum deposition velocity vd = 1.3 mm s−1 measured with the gradient pole. The lead surface behaved as a weak particle source before freeze-up with an upward flux Fc = 5.7 × 104 particles m−2 s−1, and as a relatively strong heat source after freeze-up, with an upward maximum sensible heat flux H = 13.1 W m−2. Over the frozen lead, however, we were unable to resolve any significant aerosol profiles.

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