scholarly journals Modelling inter-annual sea-ice variability off eastern Canada

1997 ◽  
Vol 25 ◽  
pp. 322-326
Author(s):  
J. R. Makko ◽  
D. B. Fissel ◽  
D. Haller
Keyword(s):  
Sea Ice ◽  
Heat Fluxes ◽  
Box Model ◽  
Surface Currents ◽  
Eastern Canada ◽  
Near Surface ◽  
Surface Temperatures ◽  
External Model ◽  
Good Reproduction ◽  
Ice Conditions

Inter-annual sea-ice variability north of 55°N in eastern Canada was explored with a box model incorporating annually invariant, bathymetrically dependent ocean heat fluxes and near-surface currents. Using inputs of ice concentrations, regional surface temperatures and geostrophic winds at external model boundaries, ice composition was simulated in seven thickness categories at 10 day intervals during three annual ice seasons. Comparisons indicated good reproduction of observed inter-annual differences in regional ice volumes during critical January-March periods. Additional simulations of artificial cutoffs in southward ice fluxes showed that advective influence decreases with latitude and dominates the development of spring ice conditions in areas south of 60°N.

scholarly journals Modelling inter-annual sea-ice variability off eastern Canada

1997 ◽  
Vol 25 ◽  
pp. 322-326
Author(s):  
J. R. Makko ◽  
D. B. Fissel ◽  
D. Haller
Keyword(s):  
Sea Ice ◽  
Heat Fluxes ◽  
Box Model ◽  
Surface Currents ◽  
Eastern Canada ◽  
Near Surface ◽  
Surface Temperatures ◽  
External Model ◽  
Good Reproduction ◽  
Ice Conditions

Inter-annual sea-ice variability north of 55°N in eastern Canada was explored with a box model incorporating annually invariant, bathymetrically dependent ocean heat fluxes and near-surface currents. Using inputs of ice concentrations, regional surface temperatures and geostrophic winds at external model boundaries, ice composition was simulated in seven thickness categories at 10 day intervals during three annual ice seasons. Comparisons indicated good reproduction of observed inter-annual differences in regional ice volumes during critical January-March periods. Additional simulations of artificial cutoffs in southward ice fluxes showed that advective influence decreases with latitude and dominates the development of spring ice conditions in areas south of 60°N.

scholarly journals The importance of capturing late melt season sea ice conditions for modeling the western Arctic ocean boundary layer

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Shawn G. Gallaher
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Late Summer ◽  
Open Water ◽  
Heat Fluxes ◽  
Conductive Heat ◽  
Near Surface ◽  
Ice Conditions ◽  
Western Arctic ◽  
Ocean Boundary

To better understand the response of the western Arctic upper ocean to late summer ice-ocean interactions, a range of surface, interior, and basal sea ice conditions were simulated in a 1-D turbulent boundary layer model. In-ice and under-ice autonomous observations from the 2014 Marginal Ice Zone Experiment provided a complete characterization of the late melt-season sea ice and were used to set initial conditions, update boundary conditions, and conduct model validation studies. Results show that underestimates of open water and melt pond fraction at the sea ice surface had the largest influence on ocean-to-ice turbulent heat fluxes reducing basal melt rates by as much as 32%. This substantial reduction in latent heat loss was attributed to underestimates of open water areas and the exclusion of melt ponds by low-resolution synthetic aperture radar imagery. However, the greatest overall effect on the ice-ocean boundary layer came from mischaracterizations of basal roughness, with smooth ice scenarios resulting in 7 m of summer halocline shoaling and preservation of the near-surface temperature maximum. Rough ice conditions showed a 23% deepening of the mixed layer and erosion of heat storage above 40 m. Adjustments of conductive heat fluxes had little effect on the near-interface heat budget due to small internal thermal gradients within the late summer sea ice. Results from the 1-D boundary layer simulations highlight the most influential components of sea ice structure during late summer conditions and provide the magnitude of errors expected when ice conditions are mischaracterized.

scholarly journals Radiometrie measurements of sea-ice surface temperature in East Antarctica

1998 ◽  
Vol 27 ◽  
pp. 466-470
Author(s):  
Kelvin J. Michael ◽  
Clemente S. Hungria ◽  
R. A. Massom
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Snow Cover ◽  
Open Water ◽  
Thermal Infrared ◽  
Near Surface ◽  
Video Footage ◽  
Antarctic Sea Ice ◽  
Ice Surface ◽  
Ice Conditions

This paper presents surface temperature data collected over East Antarctic sea ice by two thermal infrared radiometers mounted on the RSV Aurora Australis in March-May 1993. Operating at wavelengths equivalent to those utilised by channels 4 and 5 of AVHRR and similar channels of ATSR, the radiometers provided high-reso-lution data on surface (skin) temperature along the ship track. Additional information on the sea-ice conditions was obtained from hourly observations made from The ship's bridge, video footage and direct measurements made at ice stations. Following calibration, time series of temperatures from each of the radiometers were compared wi th ice-surface and near-surface air temperatures. Observed changes in the surface temperature are related to different snow and ice conditions. For a given air temperature, the surface temperature depends upon the thickness of ice and its snow cover. While open water areas (leads) have temperatures near -2.0°C, thick ice is characterised by surface temperatures which approximate those of the air. Taken as a whole, the along-track profile of surface temperature provides a proxy estimate of The proportion of open water and thin ice with in the pack. The presence of a snow cover has a significant effect on the surface temperature. It is anticipated that the results will be of use in the validation of sea-ice models and satellite thermal infrared data.

scholarly journals Observed microphysical changes in Arctic mixed-phase clouds when transitioning from sea ice to open ocean

2016 ◽  
Author(s):  
G. Young ◽  
H. M. Jones ◽  
T. W. Choularton ◽  
J. Crosier ◽  
K. N. Bower ◽  
...  
Keyword(s):  
Sea Ice ◽  
Liquid Water Content ◽  
Cloud Microphysics ◽  
Heat Fluxes ◽  
The Arctic ◽  
Cloud Base ◽  
Surface Boundary ◽  
Sea Ice Extent ◽  
Near Surface

Abstract. In situ airborne observations of cloud microphysics, aerosol properties and thermodynamic structure over the transition from sea ice to ocean are presented from the Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign. A case study from 23 March 2013 provides a unique view of the cloud microphysical changes over this transition under cold air outbreak conditions. Cloud base and depth both increased over this transition, and mean droplet number concentrations also increased from approximately 80 cm−3 over the sea ice to 90 cm−3 over the ocean. The ice properties of the cloud remained approximately constant. Observed ice crystal concentrations averaged approximately 0.5–1.5 L−1, suggesting only primary ice nucleation was active; however, there was evidence of crystal fragmentation at cloud base over the ocean. The liquid-water content increased almost four-fold over the transition and this, in conjunction with the deeper cloud layer, allowed rimed snowflakes to develop which precipitated out of cloud base. Little variation in aerosol particle number concentrations was observed between the different surface conditions; however, some variability with altitude was observed, with notably greater concentrations measured at higher altitudes (> 800 m) over the sea ice. Near-surface boundary layer temperatures increased by 13 °C from sea ice to ocean, with corresponding increases in surface heat fluxes and turbulent kinetic energy. These significant thermodynamic changes were concluded to be the primary driver of the microphysical evolution of the cloud. This study represents the first investigation, using in situ airborne observations, of cloud microphysical changes with changing sea ice cover and addresses the question of how the microphysics of Arctic stratiform clouds may change as the region warms and sea ice extent reduces.

scholarly journals Sensitivity of ocean circulation and sea-ice conditions to loss of West Antarctic ice shelves and ice sheet

2007 ◽  
Vol 53 (182) ◽  
pp. 490-498 ◽  
Author(s):  
Marion Bougamont ◽  
Elizabeth Hunke ◽  
Slawek Tulaczyk
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ocean Circulation ◽  
Ice Sheet ◽  
Near Surface ◽  
Ice Shelves ◽  
Antarctic Sea Ice ◽  
Poleward Heat Transport ◽  
West Antarctic ◽  
Ice Conditions

AbstractWe use a global coupled ocean-sea ice model to test the hypothesis that the disintegration of the West Antarctic ice sheet (WAIS), or just its ice shelves, may modify ocean circulation and sea-ice conditions in the Southern Ocean. We compare the results of three model runs: (1) a control run with a standard (modern) configuration of landmask in West Antarctica, (2) a no-shelves run with West Antarctic ice shelves removed and (3) a no-WAIS run. In the latter two runs, up to a few million square kilometres of new sea surface area opens to sea-ice formation, causing the volume and extent of Antarctic sea-ice cover to increase compared with the control run. In general, near-surface waters are cooler around Antarctica in the no-shelves and no-WAIS model runs than in the control run, while warm intermediate and deep waters penetrate further south, increasing poleward heat transport. Varying regional responses to the imposed changes in landmask configuration are determined by the fact that Antarctic polynyas and fast ice develop in different parts of the model domain in each run. Model results suggest that changes in the extent of WAIS may modify oceanographic conditions in the Southern Ocean.

scholarly journals Superimposed ice formation and surface energy fluxes on sea ice during the spring melt–freeze period in the Baltic Sea

2006 ◽  
Vol 52 (176) ◽  
pp. 119-127 ◽  
Author(s):  
Mats A. Granskog ◽  
Timo Vihma ◽  
Roberta Pirazzini ◽  
Bin Cheng
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
Heat Budget ◽  
Heat Fluxes ◽  
Ice Formation ◽  
Ice Thickness ◽  
Turbulent Heat ◽  
Snow Surface ◽  
Surface Temperatures ◽  
Synoptic Conditions

AbstractThe development of land-fast sea ice and overlying snow was monitored during a 4 week period, until the snow cover had completely disappeared, at a site in the Gulf of Bothnia, Baltic Sea (63.57ú N, 19.85° E). The meteorological and radiative boundary conditions were continuously recorded. During the observation period, a 15 cm thick snow layer on the ice was transformed into a 7 cm thick granular ice layer (superimposed ice) on the ice surface, contributing significantly (about 11%) to the total ice thickness. Approximately 1 cm w.e. of the snow was sublimated. Neither snow-ice formation nor basal ice growth was significant during the same period. The salinity and isotopic (δ18O) composition of the ice indicated that prior to the experiment a 7 cm layer of superimposed ice had already formed. Hence, superimposed ice layers contributed 22% of the total ice thickness by the time all snow had disappeared. The advancing spring, decrease in surface albedo, diurnal cycle in the incoming solar radiation, and synoptic-scale changes in the cloud cover and the air–ice turbulent heat fluxes caused variations in the heat budget of the snowpack. Superimposed ice formation due to refreezing of meltwater occurred during most nights of the study period, and the most important refreezing periods were under such synoptic conditions that the air and snow surface temperatures also remained below zero during daytime. In contrast to typical summer conditions in polar oceans, low snow surface temperatures acted as the primary heat sink for the refreezing of meltwater.

scholarly journals Observed microphysical changes in Arctic mixed-phase clouds when transitioning from sea ice to open ocean

2016 ◽  
Vol 16 (21) ◽  
pp. 13945-13967 ◽  
Author(s):  
Gillian Young ◽  
Hazel M. Jones ◽  
Thomas W. Choularton ◽  
Jonathan Crosier ◽  
Keith N. Bower ◽  
...  
Keyword(s):  
Sea Ice ◽  
Cloud Microphysics ◽  
Heat Fluxes ◽  
Cloud Layer ◽  
The Arctic ◽  
Cloud Base ◽  
Surface Boundary ◽  
Sea Ice Extent ◽  
Near Surface

Abstract. In situ airborne observations of cloud microphysics, aerosol properties, and thermodynamic structure over the transition from sea ice to ocean are presented from the Aerosol-Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) campaign. A case study from 23 March 2013 provides a unique view of the cloud microphysical changes over this transition under cold-air outbreak conditions. Cloud base lifted and cloud depth increased over the transition from sea ice to ocean. Mean droplet number concentrations, Ndrop, also increased from 110 ± 36 cm−3 over the sea ice to 145 ± 54 cm−3 over the marginal ice zone (MIZ). Downstream over the ocean, Ndrop decreased to 63 ± 30 cm−3. This reduction was attributed to enhanced collision-coalescence of droplets within the deep ocean cloud layer. The liquid water content increased almost four fold over the transition and this, in conjunction with the deeper cloud layer, allowed rimed snowflakes to develop and precipitate out of cloud base downstream over the ocean. The ice properties of the cloud remained approximately constant over the transition. Observed ice crystal number concentrations averaged approximately 0.5–1.5 L−1, suggesting only primary ice nucleation was active; however, there was evidence of crystal fragmentation at cloud base over the ocean. Little variation in aerosol particle number concentrations was observed between the different surface conditions; however, some variability with altitude was observed, with notably greater concentrations measured at higher altitudes ( >  800 m) over the sea ice. Near-surface boundary layer temperatures increased by 13 °C from sea ice to ocean, with corresponding increases in surface heat fluxes and turbulent kinetic energy. These significant thermodynamic changes were concluded to be the primary driver of the microphysical evolution of the cloud. This study represents the first investigation, using in situ airborne observations, of cloud microphysical changes with changing sea ice cover and addresses the question of how the microphysics of Arctic stratiform clouds may change as the region warms and sea ice extent reduces.

scholarly journals The Role of the Mean State of Arctic Sea Ice on Near-Surface Temperature Trends

2014 ◽  
Vol 27 (8) ◽  
pp. 2819-2841 ◽  
Author(s):  
E. C. van der Linden ◽  
R. Bintanja ◽  
W. Hazeleger ◽  
C. A. Katsman
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Model Formulation ◽  
Near Surface ◽  
Control Climate ◽  
Temperature Trends ◽  
Arctic Sea ◽  
Ice Conditions

Abstract Century-scale global near-surface temperature trends in response to rising greenhouse gas concentrations in climate models vary by almost a factor of 2, with greatest intermodel spread in the Arctic region where sea ice is a key climate component. Three factors contribute to the intermodel spread: 1) model formulation, 2) control climate state, and 3) internal climate variability. This study focuses on the influence of Arctic sea ice in the control climate on the intermodel spread in warming, using idealized 1% yr−1 CO2 increase simulations of 33 state-of-the-art global climate models, and combining sea ice–temperature relations on local to large spatial scales. On the Arctic mean scale, the spread in temperature trends is only weakly related to ice volume or area in the control climate, and is probably not dominated by internal variability. This suggests that other processes, such as ocean heat transport and meteorological conditions, play a more important role in the spread of long-term Arctic warming than control sea ice conditions. However, on a local scale, sea ice–warming relations show that in regions with more sea ice, models generally simulate more warming in winter and less warming in summer. The local winter warming is clearly related to control sea ice and universal among models, whereas summer sea ice–warming relations are more diverse, and are probably dominated by differences in model formulation. To obtain a more realistic representation of Arctic warming, it is recommended to simulate control sea ice conditions in climate models so that the spatial pattern is correct.

scholarly journals The impact of heterogeneous surface temperatures on the 2-m air temperature over the Arctic Ocean in spring

2012 ◽  
Vol 6 (4) ◽  
pp. 3011-3048 ◽  
Author(s):  
A. Tetzlaff ◽  
L. Kaleschke ◽  
C. Lüpkes ◽  
F. Ament ◽  
T. Vihma
Keyword(s):  
Air Temperature ◽  
Heat Fluxes ◽  
The Arctic ◽  
Sensible Heat ◽  
Near Surface ◽  
Ice Surface ◽  
Surface Temperatures ◽  
Air Temperatures ◽  
Ice Concentration ◽  
The Arctic Ocean

Abstract. The influence of spatial surface temperature changes over the Arctic Ocean on the 2-m air temperature variability is estimated using backward trajectories based on ERA-Interim and the JRA25 wind fields. They are initiated at Alert, Barrow and at the Tara drifting station. Three different methods are used. The first one compares mean ice surface temperatures along the trajectories to the observed 2-m air temperatures at the stations. The second one correlates the observed temperatures to air temperatures obtained using a simple Lagrangian box model which only includes the effect of sensible heat fluxes. For the third method, mean sensible heat fluxes from the model are correlated with the difference of the air temperatures at the model starting point and the observed temperatures at the stations. The calculations are based on MODIS ice surface temperatures and four different sets of ice concentration derived from SSM/I and AMSR-E data. Under nearly cloud free conditions, up to 90% of the 2-m air temperature variance can be explained for Alert, and 60% for Barrow using these methods. The differences are attributed to the different ice conditions, which are characterized by high ice concentration around Alert and lower ice concentration near Barrow. These results are robust for the different sets of reanalyses and ice concentration data. Near-surface winds of both reanalyses show a large inconsistency in the Central Arctic, which leads to a large difference in the correlations between modeled and observed 2-m air temperatures at Tara. Explained variances amount to 70% using JRA and only 45% using ERA. The results also suggest that near-surface temperatures at a given site are influenced by the variability of surface temperatures in a domain of about 150 to 350 km radius around the site.

scholarly journals Sea-ice conditions in the Adélie Depression, Antarctica, during besetment of the icebreaker RVXuelong

2015 ◽  
Vol 56 (69) ◽  
pp. 160-166 ◽  
Author(s):  
Mengxi Zhai ◽  
Xinqing Li ◽  
Fengming Hui ◽  
Xiao Cheng ◽  
Petra Heil ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Wind ◽  
Surface Air Temperature ◽  
Remotely Sensed ◽  
Coastal Current ◽  
Remotely Sensed Data ◽  
Spatiotemporal Resolution ◽  
Near Surface ◽  
Ice Conditions ◽  
Sar Imagery

AbstractDuring the 30th Chinese Antarctic Expedition in 2013/14, the Chinese icebreaker RVXuelonganswered a rescue call from the Russian RVAkademik Shokalskiy. While assisting the repatriation of personnel from the Russian vessel to the Australian RVAurora Australis, RVXuelongitself became entrapped within the compacted ice in the Adélie Depression region. Analysis of MODIS and SAR imagery provides a detailed description of the regional sea-ice conditions which led to the 6 day long besetment of RVXuelong. The remotely sensed imagery revealed four stages of sea-ice characteristics during the entrapment: the gathering, compaction, dispersion and calving stages. Four factors characterizing the local sea-ice conditions during late December 2013 and early January 2014 were identified: surface component of the coastal current; near-surface wind; ocean tides; and surface air temperature. This study demonstrates that shipping activity in ice-invested waters should be underpinned by general knowledge of the ice situation. In addition, during such activity high spatiotemporal resolution remotely sensed data should be acquired regularly to monitor local and regional sea-ice changes with a view to avoiding the besetment of vessels.

Sign in / Sign up

Export Citation Format

Share Document