Near‐surface ventilation as a key for modeling the thermal regime of coarse blocky rock glaciers

Pruessner, Luisa; Phillips, Marcia; Farinotti, Daniel; Hoelzle, Martin; Lehning, Michael

doi:10.1002/ppp.1978

Cited by 22 publications

(25 citation statements)

References 35 publications

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“…Our decision to assess the relationship between air temperatures and fluxes follows the recognition that heating (and potential thaw/melt) of rock glaciers, talus, and other high porosity periglacial features can be driven by sensible heat exchange (Grueber and Haeberli 2007;Pruessner et al 2018;Mühll and Haeberli 1990), in addition to conductive heat flux. Thus, the accumulation of degree days represents a reasonable metric of potential thawing of the subsurface, as is the likely case for glaciers in the region (Hoffman et al 2007).…”

Section: Sulfide Weatheringmentioning

confidence: 99%

Evidence for accelerated weathering and sulfate export in high alpine environments

Crawford

Hinckley

Litaor

et al. 2019

Environ. Res. Lett.

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High elevation alpine ecosystems-the 'water towers of the world'-provide water for human populations around the globe. Active geomorphic features such as glaciers and permafrost leave alpine ecosystems susceptible to changes in climate which could also lead to changing biogeochemistry and water quality. Here, we synthesize recent changes in high-elevation stream chemistry from multiple sites that demonstrate a consistent and widespread pattern of increasing sulfate and base cation concentrations or fluxes. This trend has occurred over the past 30 years and is consistent across multiple sites in the Rocky Mountains of the United States, western Canada, the European Alps, the Icelandic Shield, and the Himalayas in Asia. To better understand these recent changes and to examine the potential causes of increased sulfur and base cation concentrations in surface waters, we present a synthesis of global records as well as a high resolution 33 year record of atmospheric deposition and river export data from a longterm ecological research site in Colorado, USA. We evaluate which factors may be driving global shifts in stream chemistry including atmospheric deposition trends and broad climatic patterns. Our analysis suggests that recent changes in climate may be stimulating changes to hydrology and/or geomorphic processes, which in turn lead to accelerated weathering of bedrock. This cascade of effects has broad implications for the chemistry and quality of important surface water resources.

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Section: Sulfide Weatheringmentioning

confidence: 99%

Evidence for accelerated weathering and sulfate export in high alpine environments

Crawford

Hinckley

Litaor

et al. 2019

Environ. Res. Lett.

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“…This highlights ground ice as a requirement for the existence of permafrost at ice-rich, low-elevation sites. It is therefore a logical step to consider the ice content when mapping permafrost distribution, just as it is done for physics-based permafrost modelling (Hipp et al, 2012;Pruessner et al, 2018;Staub et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Distinguishing ice-rich and ice-poor permafrost to map ground temperatures and ground ice occurrence in the Swiss Alps

Kenner¹,

Nötzli²,

Hoelzle

et al. 2019

The Cryosphere

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Mountain permafrost is invisible, and mapping it is still a challenge. Available permafrost distribution maps often overestimate the permafrost extent and include large permafrost-free areas in their permafrost zonation. In addition, the representation of the lower belt of permafrost consisting of ice-rich features such as rock glaciers or ice-rich talus slopes can be challenging. These problems are caused by considerable differences in genesis and thermal characteristics between ice-poor permafrost, occurring for example in rock walls, and ice-rich permafrost. While ice-poor permafrost shows a strong correlation of ground temperature with elevation and potential incoming solar radiation, icerich ground does not show such a correlation. Instead, the distribution of ice-rich ground is controlled by gravitational processes such as the relocation of ground ice by permafrost creep or by ground ice genesis from avalanche deposits or glacierets covered with talus.We therefore developed a mapping method which distinguishes between ice-poor and ice-rich permafrost and tested it for the entire Swiss Alps. For ice-poor ground we found a linear regression formula based on elevation and potential incoming solar radiation which predicts borehole ground temperatures at multiple depths with an accuracy higher than 0.6 • C. The zone of ice-rich permafrost was defined by modelling the deposition zones of alpine mass wasting processes. This dual approach allows the cartographic representation of permafrost-free belts, which are bounded above and below by permafrost. This enables a high quality of permafrost modelling, as is shown by the validation of our map. The dominating influence of the two rather simple connected factors, elevation (as a proxy for mean annual air temperature) and solar radiation, on the distribution of ice-poor permafrost is significant for permafrost modelling in different climate conditions and regions. Indicating temperatures of ice-poor permafrost and distinguishing between ice-poor and ice-rich permafrost on a national permafrost map provides new information for users.

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“…In addition to the heat transfer processes within the blocky layer, the ground temperature depends on the evolution of the seasonal snow cover and snow height as examined by, e.g. Hoelzle et al (2001), Hanson and Hoelzle (2004), Rödder and Kneisel (2012), and Pruessner et al (2018). Zhang (2005) gives an overview of the influence of seasonal snow cover on the ground thermal regime.…”

Section: Introductionmentioning

confidence: 99%

Controlling factors of microclimate in blocky surface layers of two nearby relict rock glaciers (Niedere Tauern Range, Austria)

Wagner

Pauritsch

Mayaud

et al. 2019

Geografiska Annaler: Series A, Physical Geography

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Coarse blocky material is known to have a ground cooling effect compared to other types of unconsolidated surface material, which may have an influence on spatial distribution and conservation of permafrost. In the light of climate warming, this effect may retard permafrost degradation or exert prolonged ground cooling in general. To contribute to a better understanding of this ground cooling effect and potential influencing factors, the thermal regime of blocky surface layers of two comparable nearby relict rock glaciers with opposing aspects was investigated. Air, surface and shallow ground temperature at 1 m depth were continuously measured over a four-year period at nine locations distributed over two rock glaciers. The blocky surface layer of the SWexposed rock glacier exhibits lower and more heterogeneous temperatures than the NE-oriented despite a higher potential solar radiation. The data suggest a thinner or more discontinuous seasonal snow cover at the SW-exposed rock glacier, causing a more efficient winter cooling. The importance of air flow driven heat transfer as a source of cooling is supported by the data. Results illustrate thermal heterogeneities within blocky layers and the importance of the seasonal snow cover pattern in addition to topography and microclimatic variability in high relief terrain is hypothesized.

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Near‐surface ventilation as a key for modeling the thermal regime of coarse blocky rock glaciers

Cited by 22 publications

References 35 publications

Evidence for accelerated weathering and sulfate export in high alpine environments

Evidence for accelerated weathering and sulfate export in high alpine environments

Distinguishing ice-rich and ice-poor permafrost to map ground temperatures and ground ice occurrence in the Swiss Alps

Controlling factors of microclimate in blocky surface layers of two nearby relict rock glaciers (Niedere Tauern Range, Austria)

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