Measurements on Air Porosity of Sea Ice

The air content of sea ice can be measured directly by melting a sample and collecting the released air, provided the air saturation ratio in the meltwater is known. The saturation ratio was found experimentally to be a function of three parameters: the time after an ice sample was melted, the average bubble size, and the air porosity of the sample. Since the last parameter is the term to be determined, an iteration method was employed in calculations of porosity. The bubble pressure was assumed to be at one atmospheric pressure. The vertical profile of air porosity was thus obtained for first-year sea ice in the Arctic. The results were in good agreement with estimations of porosity made from density values measured for the same samples. This indicates that the bubble pressure is near one atmospheric pressure.

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Long-term time series of Arctic tropospheric BrO derived from UV–VIS satellite remote sensing and its relation to first-year sea ice

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-11869-2020 ◽

2020 ◽

Vol 20 (20) ◽

pp. 11869-11892

Author(s):

Ilias Bougoudis ◽

Anne-Marlene Blechschmidt ◽

Andreas Richter ◽

Sora Seo ◽

John Philip Burrows ◽

...

Keyword(s):

Time Series ◽

Sea Ice ◽

Ice Age ◽

The Arctic ◽

First Year ◽

Vertical Column ◽

Chain Reactions ◽

Heterogeneous Chain ◽

Good Agreement

Abstract. Every polar spring, phenomena called bromine explosions occur over sea ice. These bromine explosions comprise photochemical heterogeneous chain reactions that release bromine molecules, Br2, to the troposphere and lead to tropospheric plumes of bromine monoxide, BrO. This autocatalytic mechanism depletes ozone, O3, in the boundary layer and troposphere and thereby changes the oxidizing capacity of the atmosphere. The phenomenon also leads to accelerated deposition of metals (e.g., Hg). In this study, we present a 22-year (1996 to 2017) consolidated and consistent tropospheric BrO dataset north of 70∘ N, derived from four different ultraviolet–visible (UV–VIS) satellite instruments (GOME, SCIAMACHY, GOME-2A and GOME-2B). The retrieval data products from the different sensors are compared during periods of overlap and show good agreement (correlations of 0.82–0.98 between the sensors). From our merged time series of tropospheric BrO vertical column densities (VCDs), we infer changes in the bromine explosions and thus an increase in the extent and magnitude of tropospheric BrO plumes during the period of Arctic warming. We determined an increasing trend of about 1.5 % of the tropospheric BrO VCDs per year during polar springs, while the size of the areas where enhanced tropospheric BrO VCDs can be found has increased about 896 km2 yr−1. We infer from comparisons and correlations with sea ice age data that the reported changes in the extent and magnitude of tropospheric BrO VCDs are moderately related to the increase in first-year ice extent in the Arctic north of 70∘ N, both temporally and spatially, with a correlation coefficient of 0.32. However, the BrO plumes and thus bromine explosions show significant variability, which also depends, apart from sea ice, on meteorological conditions.

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Long-term Time-series of Arctic Tropospheric BrO derived from UV-VIS Satellite Remote Sensing and its Relation to First Year Sea Ice

10.5194/acp-2020-116 ◽

2020 ◽

Author(s):

Ilias Bougoudis ◽

Anne-Marlene Blechschmidt ◽

Andreas Richter ◽

Sora Seo ◽

John Philip Burrows ◽

...

Keyword(s):

Time Series ◽

Sea Ice ◽

Ice Age ◽

The Arctic ◽

First Year ◽

Arctic Amplification ◽

Vertical Column ◽

The Impact ◽

Good Agreement

Abstract. Arctic Amplification describes the rapid increase of the air temperature in the past three decades in the Arctic, which impacts on physicochemical conditions, the ecosystem and biogeochemistry. Every polar spring, the BrO explosion, a series of chemical reactions that release bromine molecules to the troposphere occurs over sea ice covered regions. This autocatalytic mechanism depletes boundary layer and tropospheric ozone, thereby changes the oxidizing capacity of the atmosphere and facilitates the deposition of metals (e.g. Hg). In this study, we present a 22 year consolidated and consistent tropospheric BrO dataset, derived from four different UV-VIS satellite instruments and investigate the BrO evolution under the impact of Arctic Amplification. The retrieval data products from the different sensors are compared during periods of overlap and show good agreement. By studying the sensor merged time-series of tropospheric BrO vertical column densities, we find an increase in the magnitude of BrO explosion events under the impact of Arctic Amplification with an upward trend of about 1.5 % per year. Furthermore, the areas where BrO plumes frequently appear have changed, extending over larger regions in the Arctic during more recent years. Comparison to sea ice age data suggests that the reported changes in tropospheric BrO are linked in a complex way to the increase of first-year ice extent in the Arctic.

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Anomalous blocking over Greenland preceded the 2013 extreme early melt of local sea ice

Annals of Glaciology ◽

10.1017/aog.2017.30 ◽

2017 ◽

Vol 59 (76pt2) ◽

pp. 181-190 ◽

Cited By ~ 5

Author(s):

Thomas J. Ballinger ◽

Edward Hanna ◽

Richard J. Hall ◽

Thomas E. Cropper ◽

Jeffrey Miller ◽

...

Keyword(s):

Sea Ice ◽

North Atlantic ◽

Regional Climate ◽

Regional Climate Change ◽

Circulation Pattern ◽

The Arctic ◽

Labrador Sea ◽

First Year ◽

Tropospheric Circulation ◽

Blocking Index

ABSTRACTThe Arctic marine environment is undergoing a transition from thick multi-year to first-year sea-ice cover with coincident lengthening of the melt season. Such changes are evident in the Baffin Bay-Davis Strait-Labrador Sea (BDL) region where melt onset has occurred ~8 days decade−1 earlier from 1979 to 2015. A series of anomalously early events has occurred since the mid-1990s, overlapping a period of increased upper-air ridging across Greenland and the northwestern North Atlantic. We investigate an extreme early melt event observed in spring 2013. (~6σ below the 1981–2010 melt climatology), with respect to preceding sub-seasonal mid-tropospheric circulation conditions as described by a daily Greenland Blocking Index (GBI). The 40-days prior to the 2013 BDL melt onset are characterized by a persistent, strong 500 hPa anticyclone over the region (GBI >+1 on >75% of days). This circulation pattern advected warm air from northeastern Canada and the northwestern Atlantic poleward onto the thin, first-year sea ice and caused melt ~50 days earlier than normal. The episodic increase in the ridging atmospheric pattern near western Greenland as in 2013, exemplified by large positive GBI values, is an important recent process impacting the atmospheric circulation over a North Atlantic cryosphere undergoing accelerated regional climate change.

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Net community production in the bottom of first-year sea ice over the Arctic spring bloom

Geophysical Research Letters ◽

10.1002/2017gl074602 ◽

2017 ◽

Vol 44 (17) ◽

pp. 8971-8978 ◽

Cited By ~ 8

Author(s):

K. Campbell ◽

C. J. Mundy ◽

M. Gosselin ◽

J. C. Landy ◽

A. Delaforge ◽

...

Keyword(s):

Sea Ice ◽

Spring Bloom ◽

The Arctic ◽

First Year ◽

Net Community Production ◽

Community Production

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Distribution and Driving Mechanism of N2O in Sea Ice and Its Underlying Seawater during Arctic Melt Season

Water ◽

10.3390/w14020145 ◽

2022 ◽

Vol 14 (2) ◽

pp. 145

Author(s):

Jian Liu ◽

Liyang Zhan ◽

Qingkai Wang ◽

Man Wu ◽

Wangwang Ye ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Ice Core ◽

The Arctic ◽

First Year ◽

Driving Mechanism ◽

Biogeochemical Processes ◽

Ice Melting ◽

Detailed Mechanism ◽

The Arctic Ocean

Nitrous oxide (N2O) is the third most important greenhouse gas in the atmosphere, and the ocean is an important source of N2O. As the Arctic Ocean is strongly affected by global warming, rapid ice melting can have a significant impact on the N2O pattern in the Arctic environment. To better understand this impact, N2O concentration in ice core and underlying seawater (USW) was measured during the seventh Chinese National Arctic Research Expedition (CHINARE2016). The results showed that the average N2O concentration in first-year ice (FYI) was 4.5 ± 1.0 nmol kg−1, and that in multi-year ice (MYI) was 4.8 ± 1.9 nmol kg−1. Under the influence of exchange among atmosphere-sea ice-seawater systems, brine dynamics and possible N2O generation processes at the bottom of sea ice, the FYI showed higher N2O concentrations at the bottom and surface, while lower N2O concentrations were seen inside sea ice. Due to the melting of sea ice and biogeochemical processes, USW presented as the sink of N2O, and the saturation varied from 47.2% to 102.2%. However, the observed N2O concentrations in USW were higher than that of T-N2OUSW due to the sea–air exchange, diffusion process, possible N2O generation mechanism, and the influence of precipitation, and a more detailed mechanism is needed to understand this process in the Arctic Ocean.

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A Thermodynamic Model of the Formation, Growth, and Decay of First-Year Sea Ice

Journal of Glaciology ◽

10.3189/s0022143000005414 ◽

1987 ◽

Vol 33 (113) ◽

pp. 105-119 ◽

Cited By ~ 3

Author(s):

R. Gabison

Keyword(s):

Sea Ice ◽

Thermodynamic Model ◽

Model Performance ◽

Melting Process ◽

The Arctic ◽

First Year ◽

Climatological Data ◽

Oceanic Tides ◽

Waves And Tides ◽

Improved Model

AbstractThe formulation and application of a onedimensional sea-ice thermodynamic model is presented in this paper. The model’s sensitivity to changes in oceanic and atmospheric parameters is analyzed and compared with previous studies. The model is next applied to three locations in the Arctic: Cambridge Bay, Frobisher Bay, and Alert Inlet to study the model’s ability to simulate the annual cycle of first-year ice. The model’s results are compared with available climatological data and discussed in terms of the main thermodynamic processes, the combined effects of oceanic tides, and of sea-ice deterioration by melting on the break-up of sea ice.It is shown that the model is effective in simulating the climatology of the first-year ice thickness at the three Arctic locations. The study also suggests that improved model performance can be expected from additional research and application of flexural forcing of the ice by waves and tides, and of deterioration of ice strength during the melting process.

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A Moored Arctic Floater in First-Year Sea Ice Ridges

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4028814 ◽

2015 ◽

Vol 137 (1) ◽

Cited By ~ 2

Author(s):

Oddgeir Dalane ◽

Vegard Aksnes ◽

Sveinung Løset

Keyword(s):

Sea Ice ◽

Cross Sectional Area ◽

The Arctic ◽

First Year ◽

Sectional Area ◽

Cross Sectional ◽

Ridge Structure ◽

Structure Interaction ◽

Ship Model ◽

Mooring Forces

First-year sea ice ridges are a major concern for structures operating in the Arctic offshore and will in many cases give the design mooring load. In this paper, the response of a moored conical floater, somewhat similar to the well-known Kulluk, is studied in first-year ridges. The study is based on model tests performed at Hamburg Ship Model Basin (HSVA) in several ridges with different properties. Mooring forces and floater response, resulting from interaction with different ridges, were compared with respect to ridge properties, ridge behavior, and simulated ice management. Clearance of accumulated rubble upstream the structure was the dominating physical process in the ridge–structure interaction. Accumulation of rubble caused large mooring forces. The amount of accumulated rubble depended on the ridge cross-sectional area, thus the mooring forces increased with ridge cross-sectional area. Large mooring forces were also experienced after the ridge was passed by the structure due to difficulties with clearing of accumulated rubble.

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Tensile fracture of a single crack in first-year sea ice

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2017.0346 ◽

2018 ◽

Vol 376 (2129) ◽

pp. 20170346 ◽

Cited By ~ 8

Author(s):

J. P. Dempsey ◽

D. M. Cole ◽

S. Wang

Keyword(s):

Sea Ice ◽

Field Trips ◽

Cohesive Crack ◽

The Arctic ◽

Tensile Fracture ◽

First Year ◽

Crack Model ◽

Separation Curve ◽

Ice Phenomena

The break-up of sea ice in the Arctic and Antarctic has been studied during three field trips in the spring of 1993 at Resolute, NWT, and the fall of 2001 and 2004 on McMurdo Sound via in situ cyclic loading and fracture experiments. In this paper, the back-calculated fracture information necessary to the specification of an accurate viscoelastic fictitious (cohesive) crack model is presented. In particular, the changing shape of the stress separation curve with varying conditions and loading scenarios is revealed. This article is part of the theme issue ‘Modelling of sea-ice phenomena’.

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Estimating Underwater Light Regime under Spatially Heterogeneous Sea Ice in the Arctic

Applied Sciences ◽

10.3390/app8122693 ◽

2018 ◽

Vol 8 (12) ◽

pp. 2693 ◽

Cited By ~ 11

Author(s):

Philippe Massicotte ◽

Guislain Bécu ◽

Simon Lambert-Girard ◽

Edouard Leymarie ◽

Marcel Babin

Keyword(s):

Sea Ice ◽

Water Column ◽

Attenuation Coefficient ◽

Vertical Profile ◽

Light Field ◽

Incident Light ◽

Single Point ◽

The Arctic ◽

Large Area ◽

Average Irradiance

The vertical diffuse attenuation coefficient for downward plane irradiance ( K d ) is an apparent optical property commonly used in primary production models to propagate incident solar radiation in the water column. In open water, estimating K d is relatively straightforward when a vertical profile of measurements of downward irradiance, E d , is available. In the Arctic, the ice pack is characterized by a complex mosaic composed of sea ice with snow, ridges, melt ponds, and leads. Due to the resulting spatially heterogeneous light field in the top meters of the water column, it is difficult to measure at single-point locations meaningful K d values that allow predicting average irradiance at any depth. The main objective of this work is to propose a new method to estimate average irradiance over large spatially heterogeneous area as it would be seen by drifting phytoplankton. Using both in situ data and 3D Monte Carlo numerical simulations of radiative transfer, we show that (1) the large-area average vertical profile of downward irradiance, E d ¯ ( z ) , under heterogeneous sea ice cover can be represented by a single-term exponential function and (2) the vertical attenuation coefficient for upward radiance ( K L u ), which is up to two times less influenced by a heterogeneous incident light field than K d in the vicinity of a melt pond, can be used as a proxy to estimate E d ¯ ( z ) in the water column.

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