Knut V. Høyland

Ice thickness, growth and salinity in Van Mijenfjorden, Svalbard, Norway

This paper describes measurements of ice conditions in the fjord Van Mijenfjorden, Spitsbergen, in the Svalbard Archipelago, between 1998 and 2006. Ice thickness, ice temperatures and ice properties were measured, and simple simulations of oceanic flux were performed. The maximum annual peak ice thickness was measured in 2004: 1.3 m in the inner basin and 1.2 m in the outer basin. The minimum annual peak thickness was 0.72 m in the inner basin and no fast ice in the outer basin, in 2006. The estimated oceanic flux was about 2–5 W m-2 in the outer basin, and was close to zero in the inner basin. Flooding and brine drainage may have caused an overestimation of the oceanic flux. The measurements demonstrate different ice growth mechanisms, and the simplest model (Stefan’s Law with air temperatures and a correction factor) fails to predict the ice growth. Finally, there is reason to believe that the ice conditions were heavier in the 1980s.

Measurements of temperature distribution, consolidation and morphology of a first-year sea ice ridge

Measurements of temperature distribution, consolidation and morphology of a first-year sea ice ridge

Simulations of the consolidation process in first-year sea ice ridges

Abstract A two-dimensional finite element model has been used to simulate the temperature development in first-year ice ridges and in the surrounding level ice. The program ABAQUS has been applied with user-defined subroutines to calculate the thermal loads. Meteorological weather data is used as input into these sub-routines and the sensible (convective) flux, the latent flux and the long- and short-wave radiation from the surface is calculated. Two material models have been applied: (1) a composite material consisting of sea ice and water with ordinary sea ice/water thermal properties, and (2) a homogeneous equivalent material. The measured growth of the consolidated layer in three first-year sea ice ridges has been simulated. However, modifications of the conductive model have to be done in order to handle the initial phase in which convection is crucial. One-dimensional simulations have been used to estimate the theoretical limit of the ratio of the thickness of the consolidated layer to the thickness of the level ice. Limit values as functions of the porosity have been found. The question whether this limit is a maximum value or not, is determined by processes in the initial phase. If the consolidated layer during the initial phase does not exceed this limit value it becomes a maximum, and vice versa.

Time variability in the annual cycle of sea ice thickness in the Transpolar Drift

The annual cycle of modal and mean sea ice thickness was derived from upward looking sonar ice thickness observations (1990–2011) in Fram Strait. The average annual peak-to-trough amplitude of the mode of 0.54 m is superimposed on interannual variability with peak-to-trough amplitudes of 0.73 m on time scales of 6–8 years, which again is superimposed on a long-term trend of −0.55 m/decade over the observation period. The long-term trend is stronger for April than for August, the average months of maximum and minimum modal thickness. As a result, the annual peak-to-trough modal thickness amplitude was reduced by 30% between the 1990s and the 2000s. The average annual peak-to-trough amplitude of the mean ice thickness of 1.20 m is also superimposed on interannual variability, with as much as 0.97 m thickness change over only 3 years. These two modes of variability are superimposed on a long-term trend of −0.35 m/decade through the entire data set. In contrast to the modal thickness, the long-term trend is weaker for the average month of maximum mean thickness (June), than for the average month of minimum (September). Therefore, the annual peak-to-trough amplitude of the mean ice thickness increased by 14% between the 1990s and the 2000s.

Modeling Surface Temperatures for Snow-Covered Roads: A Case Study for a Heated Pavement in Bærum, Norway

Heated pavements are used as an alternative to removing snow and ice mechanically and chemically. Usually a heated pavement system is automatically switched on when snowfall starts or when there is a risk of ice formation. Ideally, these systems run based on accurate predictions of surface conditions a couple of hours ahead of time, for which both weather forecasts and reliable surface temperature predictions are needed. The effective thermal conductivity of the snow layer is often described as a function of its density. However the thermal conductivity of a snow layer can vary considerably, not only for snow samples with a different density, but also for snow samples with the same density, but with a variation in the liquid water content. In this paper a physical temperature and surface condition model is described for snow-covered roads. The model is validated for an entire winter season on a heated pavement in Norway. Two different models to describe the thermal conductivity through the snow layer were compared. Results show that the thermal conductivity of the snow layer can be best described as a function of the density for snow with a low liquid water content. For snow with a high water content, the thermal conductivity can be best described as a function of the volume fractions and thermal conductivity of ice, water, and air, in which air and ice are modeled as a series system and water and air/ice in parallel.

Study of the Volumetric Behaviour of Ice Rubble Based on Bi-Axial Compression Data

Rubble ice in unconsolidated part of ice ridges or rubble fields for some engineering applications can be considered as a granular material. The common practice is to assume that the ice rubble obeys Mohr-Coulomb failure criterion which requires cohesion and internal friction angle as material parameters (see e.g. [1]). In order to obtain friction angle of ice rubble in small scale a bi-axial compression apparatus was proposed by Timco et al. [2]. Later, analyzing test results obtained from this apparatus Timco and Cornett [3] made a rather surprising conclusion that the ice rubble angle of friction is not a constant but has different values for different ratios of strains applied to the sample. This paper gives an overview of biaxial compression data available in the literature. It also shows that if volumetric behavior is included (which is not the case for Mohr-Coulomb criterion) then tests performed on the same types of ice rubble gives the same constant describing shearing resistance independent of applied boundary conditions.© 2014 ASME