ON THE FACTORS AFFECTING THE RATE OF ABLATION OF SEA ICE

1966 ◽  
Vol 3 (4) ◽  
pp. 431-439 ◽  
Author(s):  
M. P. Langleben
Keyword(s):  
Sea Ice ◽  
Heat Budget ◽  
Ice Sheet ◽  
Ablation Rate ◽  
Shortwave Radiation ◽  
Dominant Factor ◽  
Wave Radiation ◽  
First Year ◽  
Factors Affecting ◽  
Thermal Content

A study has been made of the heat budget just before and during the season of ablation, of first year sea ice near the head of Tanquary Fiord. Ablation started as the air temperature approached 0 °C, producing a decrease in albedo from approximately 0.6 to 0.2 in less than a week. Typical values of incident shortwave radiation were 800 cal cm−2 day−1 on clear days and 400 cal cm−2 day−1 during heavy overcast. The net influx of all-wave radiation was about 350 cal cm−2 day−1 during the ablation period, and resulted in a rate of ablation of ice of approximately 4 cm day−1.It is shown that the flux of radiative heat is the dominant factor determining the ablation rate and the change in thermal content of the ice sheet. Upward conduction from the sea is small, except when surface melt runoff occurs and collects in a stable layer immediately under the ice sheet. Even partial refreezing in this layer may release large quantities of latent heat to increase the rate of bottom conduction appreciably.

scholarly journals Structure Of The Energy Balance In The Ice Sheet-Atmosphere System As An Index Of Antarctic Glaciation (Abstract only)

1982 ◽  
Vol 3 ◽  
pp. 343
Author(s):  
V. G. Aver'yanov
Keyword(s):  
Heat Budget ◽  
Ice Sheet ◽  
Surface Radiation ◽  
Wave Radiation ◽  
Radiation Balance ◽  
Antarctic Ice Sheet ◽  
Atmosphere System ◽  
Long Wave ◽  
The Antarctic ◽  
Long Wave Radiation

Various methods have been used to estimate mean multi-year values of moisture, radiation, and heat exchange in the Antarctic ice sheet/atmosphere system. The major components of the balance have been determined as absolute and relative values. The net advection of moisture is taken as 100%, of which 83% is deposited as accumulation on the ice sheet, and the residue in the atmosphere is 15%; loss from the icesheet surface is 2%. In the radiation balance, input at the top of the atmosphere is 57%, absorption in the atmosphere is 43%, loss due to reflected shortwave radiation is 35%, and long-wave radiation from the atmosphere is 78%, while net outgoing long-wave radiation from the surface is 9%. The heat-budget components are: The Antarctic ice sheet is a vast heat sink. Constant negative surface-radiation balance and low temperature of the ice sheet suggests that it will survive with even small amounts of precipitation. Thus the contemporary glaciation of Antarctica is rather stable.

scholarly journals Ice action on Nanisivik wharf, Strathcona Sound, N.W.T., winter 1978–1979

1980 ◽  
Vol 7 (3) ◽  
pp. 558-563 ◽  
Author(s):  
R. M. W. Frederking
Keyword(s):  
Sea Ice ◽  
Vertical Movement ◽  
Consistent Pattern ◽  
Ice Thickness ◽  
First Year ◽  
Field Observations ◽  
Factors Affecting

Field observations have been made over three winters at a vertically faced wharf in an area of limited horizontal ice movement but substantial vertical movement due to tides. Ice thickness was profiled and vertical ice movements were measured. A reasonably consistent pattern of ice behaviour adjacent to the wharf was established, characterized by the formation of a transition ice zone between the first-year sea ice and the wharf. The behaviour and factors affecting growth of this zone are described.

scholarly journals A Simple Energy-Balance Model to Calculate Ice Ablation at the Margin of the Greenland Ice Sheet

1990 ◽  
Vol 36 (123) ◽  
pp. 222-228 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Ole Β. Olesen
Keyword(s):  
Energy Balance ◽  
Sensible Heat Flux ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ablation Rate ◽  
Short Wave ◽  
Energy Balance Model ◽  
Balance Model ◽  
Wave Radiation ◽  
Climate Data

AbstractData for daily ice ablation on two outlets from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), are used to test a simple energy-balance model which calculates ablation from climate data. The mean errors of the model are only −1.1 and −1.3 mm water d−1 for Nordbogletscher (14 months) and Qamanârssûp sermia (21 months), respectively, with standard deviations of ±13.6 and ±18.9 mm water d−1 for calculating daily ablation. The larger error for Qamanârssûp sermia may be due to variations in ice albedo but the model also underestimates ablation during Föhn events.According to the model, radiation accounts for about two-thirds of mean ablation for June-August at the two sites, while turbulent fluxes account for about one-third. The average ablation rate is higher at Qamanârssûp sermia than at Nordbogletscher because both sensible-heat flux and short-wave radiation are higher.

scholarly journals Comparison of a coupled snow thermodynamic and radiative transfer model with in situ active microwave signatures of snow-covered smooth first-year sea ice

2015 ◽  
Vol 9 (6) ◽  
pp. 2149-2161 ◽  
Author(s):  
M. C. Fuller ◽  
T. Geldsetzer ◽  
J. Yackel ◽  
J. P. S. Gill
Keyword(s):  
Sea Ice ◽  
Reanalysis Data ◽  
Physical Models ◽  
Radiative Transfer Model ◽  
Wave Radiation ◽  
First Year ◽  
Transfer Model ◽  
Long Wave ◽  
Microwave Backscatter

Abstract. Within the context of developing data inversion and assimilation techniques for C-band backscatter over sea ice, snow physical models may be used to drive backscatter models for comparison and optimization with satellite observations. Such modeling has the potential to enhance understanding of snow on sea-ice properties required for unambiguous interpretation of active microwave imagery. An end-to-end modeling suite is introduced, incorporating regional reanalysis data (NARR), a snow model (SNTHERM89.rev4), and a multilayer snow and ice active microwave backscatter model (MSIB). This modeling suite is assessed against measured snow on sea-ice geophysical properties and against measured active microwave backscatter. NARR data were input to the SNTHERM snow thermodynamic model in order to drive the MSIB model for comparison to detailed geophysical measurements and surface-based observations of C-band backscatter of snow on first-year sea ice. The NARR variables were correlated to available in situ measurements with the exception of long-wave incoming radiation and relative humidity, which impacted SNTHERM simulations of snow temperature. SNTHERM snow grain size and density were comparable to observations. The first assessment of the forward assimilation technique developed in this work required the application of in situ salinity profiles to one SNTHERM snow profile, which resulted in simulated backscatter close to that driven by in situ snow properties. In other test cases, the simulated backscatter remained 4–6 dB below observed for higher incidence angles and when compared to an average simulated backscatter of in situ end-member snow covers. Development of C-band inversion and assimilation schemes employing SNTHERM89.rev4 should consider sensitivity of the model to bias in incoming long-wave radiation, the effects of brine, and the inability of SNTHERM89.Rev4 to simulate water accumulation and refreezing at the bottom and mid-layers of the snowpack. These impact thermodynamic response, brine wicking and volume processes, snow dielectrics, and thus microwave backscatter from snow on first-year sea ice.

scholarly journals Improving the WRF model's (version 3.6.1) simulation over sea ice surface through coupling with a complex thermodynamic sea ice model (HIGHTSI)

2016 ◽  
Vol 9 (6) ◽  
pp. 2239-2254 ◽  
Author(s):  
Yao Yao ◽  
Jianbin Huang ◽  
Yong Luo ◽  
Zongci Zhao
Keyword(s):  
Sea Ice ◽  
Heat Budget ◽  
Wrf Model ◽  
The Arctic ◽  
Wave Radiation ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
The Impact ◽  
Ice Model ◽  
Snow And Ice

Abstract. Sea ice plays an important role in the air–ice–ocean interaction, but it is often represented simply in many regional atmospheric models. The Noah sea ice scheme, which is the only option in the current Weather Research and Forecasting (WRF) model (version 3.6.1), has a problem of energy imbalance due to its simplification in snow processes and lack of ablation and accretion processes in ice. Validated against the Surface Heat Budget of the Arctic Ocean (SHEBA) in situ observations, Noah underestimates the sea ice temperature which can reach −10 °C in winter. Sensitivity tests show that this bias is mainly attributed to the simulation within the ice when a time-dependent ice thickness is specified. Compared with the Noah sea ice model, the high-resolution thermodynamic snow and ice model (HIGHTSI) uses more realistic thermodynamics for snow and ice. Most importantly, HIGHTSI includes the ablation and accretion processes of sea ice and uses an interpolation method which can ensure the heat conservation during its integration. These allow the HIGHTSI to better resolve the energy balance in the sea ice, and the bias in sea ice temperature is reduced considerably. When HIGHTSI is coupled with the WRF model, the simulation of sea ice temperature by the original Polar WRF is greatly improved. Considering the bias with reference to SHEBA observations, WRF-HIGHTSI improves the simulation of surface temperature, 2 m air temperature and surface upward long-wave radiation flux in winter by 6, 5 °C and 20 W m−2, respectively. A discussion on the impact of specifying sea ice thickness in the WRF model is presented. Consistent with previous research, prescribing the sea ice thickness with observational information results in the best simulation among the available methods. If no observational information is available, we present a new method in which the sea ice thickness is initialized from empirical estimation and its further change is predicted by a complex thermodynamic sea ice model. The ice thickness simulated by this method depends much on the quality of the initial guess of the ice thickness and the role of the ice dynamic processes.

scholarly journals The tensile strength of first-year sea ice

1993 ◽  
Vol 39 (133) ◽  
pp. 609-618 ◽  
Author(s):  
J. A. Richter Menge ◽  
K. F. Jones
Keyword(s):  
Tensile Strength ◽  
Sea Ice ◽  
Maximum Stress ◽  
Ice Sheet ◽  
Tensile Load ◽  
Growth Direction ◽  
First Year ◽  
Strain Rates ◽  
Temperature Dependent

AbstractWe present the results of tests done to determine the tensile behavior of first-year columnar sea ice over a range of temperatures from −20° to −3°C and strain rates of 10−5and 10−3s−1. The temperature of a test specimen was dictated by its in-situ location within the sea-ice sheet; samples located near the top of the sea-ice sheet were tested at the lower temperatures. A tensile load was applied along the cylindrical axes of the test specimens, which were perpendicular to the growth direction of the ice. Results showed that the maximum stress reached during a test was most strongly influenced by temperature, while the failure strain and the modulus were principally affected by the loading rate. A model relating the tensile strength of the ice to its porosity based on temperature-dependent variations in the brine-pocket geometry is evaluated.

scholarly journals A Simple Energy-Balance Model to Calculate Ice Ablation at the Margin of the Greenland Ice Sheet

1990 ◽  
Vol 36 (123) ◽  
pp. 222-228 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Ole Β. Olesen
Keyword(s):  
Energy Balance ◽  
Sensible Heat Flux ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ablation Rate ◽  
Short Wave ◽  
Energy Balance Model ◽  
Balance Model ◽  
Wave Radiation ◽  
Climate Data

AbstractData for daily ice ablation on two outlets from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), are used to test a simple energy-balance model which calculates ablation from climate data. The mean errors of the model are only −1.1 and −1.3 mm water d−1for Nordbogletscher (14 months) and Qamanârssûp sermia (21 months), respectively, with standard deviations of ±13.6 and ±18.9 mm water d−1for calculating daily ablation. The larger error for Qamanârssûp sermia may be due to variations in ice albedo but the model also underestimates ablation during Föhn events.According to the model, radiation accounts for about two-thirds of mean ablation for June-August at the two sites, while turbulent fluxes account for about one-third. The average ablation rate is higher at Qamanârssûp sermia than at Nordbogletscher because both sensible-heat flux and short-wave radiation are higher.

scholarly journals Structure Of The Energy Balance In The Ice Sheet-Atmosphere System As An Index Of Antarctic Glaciation (Abstract only)

1982 ◽  
Vol 3 ◽  
pp. 343-343
Author(s):  
V. G. Aver'yanov
Keyword(s):  
Heat Budget ◽  
Ice Sheet ◽  
Surface Radiation ◽  
Wave Radiation ◽  
Radiation Balance ◽  
Antarctic Ice Sheet ◽  
Atmosphere System ◽  
Long Wave ◽  
The Antarctic ◽  
Long Wave Radiation

Various methods have been used to estimate mean multi-year values of moisture, radiation, and heat exchange in the Antarctic ice sheet/atmosphere system. The major components of the balance have been determined as absolute and relative values. The net advection of moisture is taken as 100%, of which 83% is deposited as accumulation on the ice sheet, and the residue in the atmosphere is 15%; loss from the icesheet surface is 2%. In the radiation balance, input at the top of the atmosphere is 57%, absorption in the atmosphere is 43%, loss due to reflected shortwave radiation is 35%, and long-wave radiation from the atmosphere is 78%, while net outgoing long-wave radiation from the surface is 9%. The heat-budget components are: The Antarctic ice sheet is a vast heat sink. Constant negative surface-radiation balance and low temperature of the ice sheet suggests that it will survive with even small amounts of precipitation. Thus the contemporary glaciation of Antarctica is rather stable.

scholarly journals STRENGTH CHARACTERISTICS OF THE ICE SHEET (FIRST-YEAR SEA ICE) IN FIELD INDENTATION TESTS

1999 ◽  
Vol 15 ◽  
pp. 629-633
Author(s):  
Masafumi SAKAI ◽  
Hisao MATSUSHITA ◽  
Toru TAKAWAKI ◽  
Muneo KAWAMURA ◽  
Takashi TERASHIMA ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ice Sheet ◽  
Strength Characteristics ◽  
First Year ◽  
Indentation Tests

The MOSAiC sea ice albedo record: its context and role for informing improved surface radiative budgets in a climate model 

2021 ◽  
Author(s):  
Bonnie Light ◽  
Marika Holland ◽  
Madison Smith ◽  
Donald Perovich ◽  
Melinda Webster ◽  
...  
Keyword(s):  
Optical Properties ◽  
Radiative Transfer ◽  
Sea Ice ◽  
Climate Models ◽  
Climate Model ◽  
Heat Budget ◽  
Shortwave Radiation ◽  
The Arctic ◽  
Data Sets ◽  
Seasonal Evolution

<p>Sea ice albedo is both a driver and a consequence of summer melt evolution. The ability to collect comprehensive observations and develop accurate, general, and consistent physics-based models is central to our quantitative understanding of sea ice mass and heat budgets and a variety of associated feedback processes. Sea ice albedos recorded during the MOSAiC field campaign have extended our knowledge of the optical properties of specific ice types as well as their seasonal evolution. This new dataset complements and extends observations made during the Surface Heat Budget of the Arctic Ocean (SHEBA) campaign in the Beaufort Sea in 1998. It also presents an opportunity to improve numerical treatment of shortwave radiation partitioning by sea ice covers in climate models. Specifically, the observations include spectral and broadband albedo measurements made by observers on the surface for two classes of measurement: 1) individual ice types including snow covered ice (prior to and during melt), bare melting ice, ponded ice, and sediment-laden ice, and 2) time series measured over the full seasonal cycles. The MOSAiC and SHEBA data sets show remarkable similarity with respect to the steady spectral albedo of bare, melting summer ice and the seasonal evolution measured over representative survey lines. Both data sets include coordinated physical property characterization, which is key to the development and refinement of radiative transfer treatment in climate modeling.</p><p>In this work, we compare the observational record with results generated from runs of the CESM2 model. The Community Earth System Model (CESM2) is a coupled climate model that includes a physics-based radiative transfer treatment for sea ice. This model relies on a 2-stream delta-Eddington solution with prescribed ice-type-specific inherent optical properties. Specifically, we consider newly available sub-gridscale diagnostics in the model that detail the radiative partitioning for individual surface types and thickness categories. Comparisons between observed and modeled values are considered for the albedo of individual surface types, aggregate albedo estimates, and their seasonal progression. In particular, we use these comparisons to derive a quantitative picture of the overall partitioning of shortwave radiation by the ice cover, and how it has changed over past decades. These results can help pinpoint where the most substantial model upgrades can be accomplished as well as where the best observational investments should be made.</p>

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