Canada ; Climatic warming ; Cold area ; Numerical model ; Periglacial features ; Permafrost ; Quebec ; Simulation ; Thawing
This paper shows the effect of thaw settlement on the thermal response of a small permafrost mound in Northern Québec to different scenarios of climate warming, with a finite-element, one-dimensional, heat conduction model. In addition
to the cryostratigraphy of the mound, the unfrozen water content, thermal conductivity and volumetric heat capacity of the marine sediments comprising the mound were integrated in the simulation. Thaw settlement, the direct results of ice melting in permafrost, brings
permafrost nearer to the surface and accelerates its thawing. It should be included in any numerical simulation.
Meteorological control on interannual spatial and temporal variations in snow cover and ground thawing in two northeast greenlandic Circumpolar-Active-Layer-Monitoring (CALM) sites
Active layer ; Arctic Region ; Cold area ; Greenland ; Interannual variability ; Nivation hollow ; Permafrost ; Snow cover ; Spatial variation ; Thawing
Data on snow cover depletion and ground thawing at 2 sites at Zackenberg, in high arctic northeast Greenland, are presented from 1996 to 2002, and their meteorological control discussed.
Climatic and geomorphic factors affecting contemporary (1950-2004) activity of retrogressive thaw slumps on the Aklavik Plateau, Richardson Mountains, NWT, Canada
Arctic Region ; Canada ; Climate ; Climatic change ; Ground ice ; Mass movement ; Mountain ; Northwest Territories ; Periglacial features ; Permafrost ; Thawing ; Thermokarst
The climatic and geomorphic factors affecting retrogressive thaw slump initiation and activity on the Aklavik Plateau (Richardson Mountains, NWT) were examined using historical air photographs over a 54-year period (1950-2004). All thaw slumps
on the Aklavik Plateau are located within the glacial limit of the Laurentide Ice Sheet and the majority developed on the western side of the valley on gently sloping terrain. Aerial photographic analysis showed an increase in thaw slump initiation over the 1954
-71 period and over the 1985-2004 period. However, the total number of active mature thaw slumps on the Aklavik Plateau decreased from a maximum of 46 in 1950 to a minimum of 24 observed in 2004. Both these trends may relate to the influence of climate
on the erosional processes that are thought to initiate thaw slumps and keep them active in regions of highlands.
, laboratory experiments were carried out to investigate how freezing-thawing or wetting-drying cycles, under controlled conditions, affect structure and porosity. Data from wetting-drying cycles showed that changes in water content alone did not produce deep
structural modifications. A mechanism of alteration of soil sructure during freezing-thawing cycles is proposed.
Frost heave and dry density changes during cyclic freeze-thaw of a silty clay
China ; Clay ; Cold area ; Experimentation ; Freeze-thaw cycle ; Frost ; Geotechnics ; Qinghai ; Railway ; Tibet
Open-system frost heave tests were performed on a silty clay using a lower boundary condition of +2°C and unidirectional freezing at -10°c from the surface, or freezing and thawing with an upper boundary temperature that cycled from -10°C to +10°C
or from -10°C to 0°C. The amont of frost heave, the distribution of moisture at the end of the experiment and the final dry density profiles all differed for the 3 cases. The experiments demonstrate that freeze-thaw history is important in assessing
The aim of this study was to quantify the effect of variable freeze-thaw cycles and soil moisture conditions on aggregate stability of 3 soils (silt, structured clay loam-clay A and levelled silty clay loam-clay B), which are representative of 2
erosion prone areas in southeastern Norway. A second aim was to compare aggregate stabilities measured by the Norwegian standard procedure (rainfall simulator) and the more widely used wet-sieving procedure. Freezing and thawing decreased the rainfall
Simulation of freezing-thawing cycles in a permafrost microcosm for assessing microbial methane production under extreme conditions
Arctic Region ; Biogenic process ; Cold area ; Freeze-thaw cycle ; Humid environment ; Micro-organism ; Periglacial features ; Permafrost ; Russia ; Simulation ; West Siberia
The AA. describe a new technique for the simulation of natural freezing-thawing cycles of the active layer in a permafrost microcosm. The core temperature, moisture and methane concentration and release in different depths of the microcosm can
be measured continuously under controlled freezing and thawing conditions. The simulation experiment provides an insight into the activity of microorganisms and turnover rates under various cryogenic conditions (i.e. frozen, partly frozen, unfrozen). The data
Evidence for freeze-thaw events and their implications for rock weathering in northern Canada
British Columbia ; Canada ; Chemical erosion ; Cold area ; Experimentation ; Freeze-thaw cycle ; Meltwater ; Temperature ; Weathering
. Temperature data were collected at 1 min intervals for 1 year. These data provide unequivocal proof for the occurrence of the freezing and thawing of water on and within the rock (freeze-thaw events). It was found that the temperature at which freezing occured
The AA. quantitatively test the hypothesis that soil freeze-thaw (FT) processes significantly increase the potential for upland hillslope erosion during run-off events that follow thaw. They selected a highly frost-susceptible silt to obtain
Distribution of zonal permafrost landforms with freezing and thawing indices
In areas with under 50 cm snow cover in winter, the permafrost zones can be defined by freezing indices and thawing indices. The relationship works for Norway, Spitsbergen, Canada and Mongolia, and since these include a very wide range of thermal
Estimating the variability of active-layer thaw depth in two physiographic regions of northern Alaska
Active layer ; Alaska ; Cold area ; Methodology ; Periglacial features ; Sampling ; Spatial variation ; Thawing
scale of variation of thaw depth to determine the optimal sampling distance for the 2 major physiographic provinces of northern Alaska, the Arctic Coastal Plain, and Arctic Foothills; to compare the applicability, ease of implementation, and output
The first objective of this study is to determine whether one-dimensional mathematical modelling can accurately predict the observed thaw profile in the nearshore zone of a retreating coast. The second objective is to use this model to document
of Thawed, Freeze-Thaw, Isothermal and Frozen Days showed considerable variability by elevation and microtopographic position. Variability in growing conditions was examined by calculating Thawing Degree Days and Growing Degree Days. These values, sometimes
Soil freeze-thaw-induced changes to a simulated rill : potential impacts on soil erosion
Cold area ; Freeze-thaw cycle ; Freezing ; Gully erosion ; Mass movement ; Model ; Rill wash ; Sediment transport ; Soil erosion
The objective of this study was to measure the effects of one of the soil processes that affect rill geometry, soil freeze-thaw (FT) cycling. An unvegetated rectangular rill was subjected to 2 FT cycles, each lasting several days, in a controlled
Profiles of temporal thaw depths beneath two Arctic stream types using ground-penetrating radar
Alaska ; Geophysics ; Ground ice ; Hydrodynamics ; Periglacial features ; Permafrost ; Soil temperature ; Stream ; Thawing
The aim of this study is to provide a time series of the evolution of the thaw bulb under peat-bed and alluvial stream types beneath open water during the summer season. This directly supports ongoing studies by the AA. to investigate hyporheic
Riverbank freeze-thaw erosion along a small mountain stream, Nikko volcanic area, Central Japan
Bank erosion ; Flood ; Freeze-thaw cycle ; Freezing ; Honshu ; Japan ; Mountain ; Seasonal variation ; Stream
-thaw erosion. Particular attention is paid to the seasonal pattern of the 3 erosional processes. Manual and automatic measurements were undertaken over 20 months including 2 winters along the River Yukawa, a small mountain stream in a Japanese volcanic
Physical modelling of fault scarp degradation under freeze-thaw cycles
Basse-Normandie ; Creep ; Debris flow ; Erosion ; Fault scarp ; France ; Freeze-thaw cycle ; Gelifluction ; Model ; Periglacial features ; Quaternary
Physical modelling has been developed in order to simulate the effects of periglacial erosion processes on the degradation of slopes and scarps. Data from 41 experimental freeze-thaw cycles are presented. They attest to the efficiency of periglacial