scholarly journals Thermal Characteristics of the Permafrost within an Active Rock Glacier (Murtèl/Corvatsch, Grisons, Swiss Alps)

1990 ◽  
Vol 36 (123) ◽  
pp. 151-158 ◽  
Author(s):  
Daniel Vonder Mühll ◽  
Wilfried Haeberli
Keyword(s):  
Heat Flow ◽  
Thermal Characteristics ◽  
Thermal Conditions ◽  
Swiss Alps ◽  
Mean Annual Temperature ◽  
Seasonal Temperature ◽  
Rock Glacier ◽  
Vertical Heat ◽  
Glacial Time

AbstractTemperatures from a bore hole through an active rock glacier in the eastern Swiss Alps are presented and thermal conditions within the slowly creeping permafrost are analyzed. Present mean annual temperature in the uppermost part of the permafrost is −3°C. Permafrost is 52 m thick and reaches heavily fissured bedrock. Thermal conductivity as determinedin situfrom seasonal temperature variations and measured in a cold laboratory using frozen samples is close to 2.5–3.0 W m−1°C−1. Vertical heat flow is anomalously high (around 150 mW m-2), probably due to heat advection from circulating ground water or air within the fissured bedrock zone. Beneath this zone, which could in fact represent a non-frozen intra-permafrost layer or “talik”, relic permafrost from past centuries may possibly exist as indicated by a corresponding heat-flow inversion. Given the current temperature condition at the surface of the rock glacier and the fact that the twentieth century is among the warmest in post-glacial time, permafrost conditions may be assumed to have existed during the whole of the Holocene and, hence, during the entire time of rock-glacier formation.

scholarly journals Thermal Characteristics of the Permafrost within an Active Rock Glacier (Murtèl/Corvatsch, Grisons, Swiss Alps)

1990 ◽  
Vol 36 (123) ◽  
pp. 151-158 ◽  
Author(s):  
Daniel Vonder Mühll ◽  
Wilfried Haeberli
Keyword(s):  
Heat Flow ◽  
Thermal Characteristics ◽  
Thermal Conditions ◽  
Swiss Alps ◽  
Mean Annual Temperature ◽  
Seasonal Temperature ◽  
Rock Glacier ◽  
Vertical Heat ◽  
Glacial Time

AbstractTemperatures from a bore hole through an active rock glacier in the eastern Swiss Alps are presented and thermal conditions within the slowly creeping permafrost are analyzed. Present mean annual temperature in the uppermost part of the permafrost is −3°C. Permafrost is 52 m thick and reaches heavily fissured bedrock. Thermal conductivity as determined in situ from seasonal temperature variations and measured in a cold laboratory using frozen samples is close to 2.5–3.0 W m−1 °C−1. Vertical heat flow is anomalously high (around 150 mW m-2), probably due to heat advection from circulating ground water or air within the fissured bedrock zone. Beneath this zone, which could in fact represent a non-frozen intra-permafrost layer or “talik”, relic permafrost from past centuries may possibly exist as indicated by a corresponding heat-flow inversion. Given the current temperature condition at the surface of the rock glacier and the fact that the twentieth century is among the warmest in post-glacial time, permafrost conditions may be assumed to have existed during the whole of the Holocene and, hence, during the entire time of rock-glacier formation.

scholarly journals Towards a palaeoclimatic model of rock-glacier formation in the Swiss Alps

2000 ◽  
Vol 31 ◽  
pp. 281-286 ◽  
Author(s):  
Regula Frauenfelder ◽  
Andreas Kääb
Keyword(s):  
Regional Scale ◽  
Thermal Conditions ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Swiss Alps ◽  
Inventory Analysis ◽  
Rock Glacier ◽  
Altitudinal Distribution ◽  
Polymorphic Type ◽  
Rock Glaciers

AbstractClimate and its long-term variability govern ground thermal conditions, and for this reason represent one of the most important impacts on creeping mountain permafrost. The decoding and better understanding of the present-day morphology and distribution of rock glaciers opens up a variety of insights into past and present environmental, especially climatic, conditions on a local to regional scale. The present study was carried out in the Swiss Alps using two different approaches: (1) kinematic analysis of specific active rock glaciers, and (2) description of the altitudinal distribution of relict rock glaciers. Two theoretical shape concepts of active rock-glacier morphology were derived’ a"monomorphic" type, representing presumably undisturbed, continuous development over several millennia and a ˚polymorphic" type, reflecting a system of (possibly climatically affected) individual creep streams several centuries old. The topoclimatic-based inventory analysis indicated an average temperature increase at relict rock-glacier fronts of approximately +2°C since the time of their decay, which is a sign of rock-glacier ages reaching back to the Alpine Late Glacial. The temperature difference of some tenths of a degree Celsius found for active/inactive rock glaciers is typical for the bandwidth of Holocene climate variations. These results confirm the importance of Alpine rock glaciers as highly sensitive indicators of past temperature evolution.

scholarly journals Effects of microtopography on texture, temperature and heat flow in Arctic and sub-Arctic snow

1994 ◽  
Vol 19 ◽  
pp. 63-68 ◽  
Author(s):  
Matthew Sturm ◽  
Jonathan Holmgren
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Snow Depth ◽  
In Situ Measurements ◽  
Temperature Gradients ◽  
Substantial Fraction ◽  
Model Based ◽  
Vertical Heat ◽  
Lateral Temperature

Arctic and sub-Arctic snow is deposited on ground that can have significant microrelief due to tundra hummocks and tussocks. The microrelief, a substantial fraction of the total snow depth, causes basal layers of snow (usually depth hoar) to be discontinuous. In-situ measurements made at four locations in Alaska indicate lateral temperature gradients up to 60°C m−1exist at the snow/ground interface due to the microtopography. For all sites, the winter average range of temperature along a 1.5 m transect at the interface varied from 4°C to greater than 7°C. Heat-flux transducers placed at the tops and bases of tussocks indicated that vertical heat flow was consistently 1.4 to 2.1 times higher at the top than the base. Results of a conductive model based on tussock height are consistent with these measurements.

scholarly journals Monitoring Rock Glacier Kinematics with Satellite Synthetic Aperture Radar

2020 ◽  
Vol 12 (3) ◽  
pp. 559 ◽  
Author(s):  
Tazio Strozzi ◽  
Rafael Caduff ◽  
Nina Jones ◽  
Chloé Barboux ◽  
Reynald Delaloye ◽  
...  
Keyword(s):  
Swiss Alps ◽  
European Alps ◽  
Remotely Sensed Data ◽  
Rock Glacier ◽  
Sar Images ◽  
Mountain Permafrost ◽  
Rock Glaciers ◽  
Satellite Radar ◽  
Offset Tracking

Active rock glaciers represent the best visual expression of mountain permafrost that can be mapped and monitored directly using remotely sensed data. Active rock glaciers are bodies that consist of a perennially frozen ice/rock mixture and express a distinct flow-like morphology indicating downslope permafrost creep movement. Annual rates of motion have ranged from a few millimeters to several meters per year, varying within the annual cycle, from year to year, as well as at the decennial time scale. During the last decade, in situ observations in the European Alps have shown that active rock glaciers are responding almost synchronously to inter-annual and decennial changes in ground temperature, suggesting that the relative changes of their kinematics are a general indicator of the evolution of mountain permafrost conditions. Here, we used satellite radar interferometry (InSAR) to monitor the rate of motion of various active rock glaciers in the Swiss Alps, Qeqertarsuaq (Western Greenland), and the semiarid Andes of South America. Velocity time series computed with Sentinel-1 SAR images, regularly acquired since 2014, every six days over Europe and Greenland and every 12 days over the Andes, show annual fluctuations, with higher velocities at the end of the summer. A JERS-1 image pair of 1996 and stacks of very high-resolution SAR images from TerraSAR-X and Cosmo-SkyMed from 2008 to 2017 were analyzed using InSAR and offset tracking over the Western Swiss Alps in order to extend the main observation period of our study. A quantitative assessment of the accuracy of InSAR and offset tracking was performed by comparison with in situ methods. Our results for the three different study regions demonstrate that Sentinel-1 InSAR can complement worldwide in situ measurements of active rock glacier kinematics.

scholarly journals Comparison between Heat Flow Meter (HFM) and Thermometric (THM) Method for Building Wall Thermal Characterization: Latest Advances and Critical Review

2022 ◽  
Vol 14 (2) ◽  
pp. 693
Author(s):  
Luca Evangelisti ◽  
Andrea Scorza ◽  
Roberto De Lieto Vollaro ◽  
Salvatore Andrea Sciuto
Keyword(s):  
Heat Flow ◽  
Critical Review ◽  
Thermal Conditions ◽  
Thermal Characterization ◽  
Flow Meter ◽  
Scientific Papers ◽  
Building Wall ◽  
Building Components ◽  
Heat Flow Meter

It is well-known that on-site measurements are suitable for verifying the actual thermal performance of buildings. Performance assessed in situ, under actual thermal conditions, can substantially vary from the theoretical values. Therefore, experimental measurements are essential for better comprehending the thermal behavior of building components, by applying measurement systems and methods suitable to acquire data related to temperatures, heat flows and air speeds both related to the internal and external environments. These data can then be processed to compute performance indicators, such as the well-known thermal transmittance (U-value). This review aims at focusing on two experimental techniques: the widely used and standardized heat flow meter (HFM) method and the quite new thermometric (THM) method. Several scientific papers were analyzed to provide an overview on the latest advances related to these techniques, thus providing a focused critical review. This paper aims to be a valuable resource for academics and practitioners as it covers basic theory, in situ measurement equipment and criteria for sensor installation, errors, and new data post-processing methods.

scholarly journals Effects of microtopography on texture, temperature and heat flow in Arctic and sub-Arctic snow

1994 ◽  
Vol 19 ◽  
pp. 63-68 ◽  
Author(s):  
Matthew Sturm ◽  
Jonathan Holmgren
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Snow Depth ◽  
In Situ Measurements ◽  
Temperature Gradients ◽  
Substantial Fraction ◽  
Model Based ◽  
Vertical Heat ◽  
Lateral Temperature

Arctic and sub-Arctic snow is deposited on ground that can have significant microrelief due to tundra hummocks and tussocks. The microrelief, a substantial fraction of the total snow depth, causes basal layers of snow (usually depth hoar) to be discontinuous. In-situ measurements made at four locations in Alaska indicate lateral temperature gradients up to 60°C m −1 exist at the snow/ground interface due to the microtopography. For all sites, the winter average range of temperature along a 1.5 m transect at the interface varied from 4°C to greater than 7°C. Heat-flux transducers placed at the tops and bases of tussocks indicated that vertical heat flow was consistently 1.4 to 2.1 times higher at the top than the base. Results of a conductive model based on tussock height are consistent with these measurements.

scholarly journals Development of a Field Deployable Firebrand Flux and Condition Measurement System

2020 ◽  
Author(s):  
Simone Zen ◽  
Jan C. Thomas ◽  
Eric V. Mueller ◽  
Bhisham Dhurandher ◽  
Michael Gallagher ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Time History ◽  
Infrared Camera ◽  
Thermal Conditions ◽  
Particle Characterization ◽  
Fire Dynamics ◽  
Rate Of Spread ◽  
New Instrument ◽  
History Of

AbstractA new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

scholarly journals Absolute seasonal temperature estimates from clumped isotopes in bivalve shells suggest warm and variable greenhouse climate

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Niels J. de Winter ◽  
Inigo A. Müller ◽  
Ilja J. Kocken ◽  
Nicolas Thibault ◽  
Clemens V. Ullmann ◽  
...  
Keyword(s):  
Seasonal Variability ◽  
Sea Water ◽  
Isotope Composition ◽  
Sea Surface ◽  
Mean Annual Temperature ◽  
Seasonal Temperature ◽  
Sea Surface Temperatures ◽  
Surface Temperatures ◽  
Temperature Reconstructions ◽  
Bivalve Shells

AbstractSeasonal variability in sea surface temperatures plays a fundamental role in climate dynamics and species distribution. Seasonal bias can also severely compromise the accuracy of mean annual temperature reconstructions. It is therefore essential to better understand seasonal variability in climates of the past. Many reconstructions of climate in deep time neglect this issue and rely on controversial assumptions, such as estimates of sea water oxygen isotope composition. Here we present absolute seasonal temperature reconstructions based on clumped isotope measurements in bivalve shells which, critically, do not rely on these assumptions. We reconstruct highly precise monthly sea surface temperatures at around 50 °N latitude from individual oyster and rudist shells of the Campanian greenhouse period about 78 million years ago, when the seasonal range at 50 °N comprised 15 to 27 °C. In agreement with fully coupled climate model simulations, we find that greenhouse climates outside the tropics were warmer and more seasonal than previously thought. We conclude that seasonal bias and assumptions about seawater composition can distort temperature reconstructions and our understanding of past greenhouse climates.

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