The Fractionation of Natural Isotopes During Temperature Gradient Metamorphism of Snow

Sommerfeld, R. A.; Friedman, Irving; Nilles, Mark A.

doi:10.1007/978-94-009-3947-9_5

Cited by 16 publications

(22 citation statements)

References 4 publications

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“…Moser and Stichler [1975] explored the effects of sublimation on water isotopes in experimental snowpacks and concluded that sublimation was capable of enriching the snowpack in the heavier isotopes ( 2 H and 18 O). Sommerfeld et al [1987] found similar results and showed that isotope fractionation, driven by high vapor pressure deficits, could be a sensitive tool for determining relative mass change in a column of snow. This finding has been of significant debate in field studies, as subsequent research failed to demonstrate the ability of water isotopes to gauge mass change due to sublimation because of the two‐dimensional movement of water vapor out of and into the snowpack [ Friedman et al , 1991; Moser and Stichler , 1975].…”

Section: Introductionsupporting

confidence: 54%

“…Laboratory research of experimental snowpacks found similar results showing that isotope fractionation via sublimation could be a sensitive tool for determining relative mass change in a snow column. The study concluded that the mass loss or gain at any given location within the snowpack is determined by the snowpack equilibrium vapor pressure profile [ Sommerfeld et al , 1987]. Separate field studies have concluded the isotopic fractionation of snow during sublimation is not an important process over the winter season due to the two‐dimensional interaction of water vapor.…”

Section: Discussionmentioning

confidence: 99%

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Estimating snow sublimation using natural chemical and isotopic tracers across a gradient of solar radiation

Gustafson

Brooks

Molotch

et al. 2010

Water Resources Research

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[1] Changes in both climate and vegetation may dramatically impact the amount of water stored in seasonal snow cover and the timing of spring snowmelt. This study quantifies how spatial variability in solar radiation affects the spatial and temporal patterns in snow water equivalent (SWE), snow chemistry, and snow water isotopes in the Jemez Mountains, New Mexico. Depth, density, stratigraphy, temperature, and snow samples were collected approximately monthly from five locations between January and April 2007 to quantify the effects of solar forcing on snowpack water and chemical balance. Locations varied in solar forcing due to topography and vegetation, while minimizing variability in precipitation, elevation, aspect, interception, and wind redistribution. Snowfall (340 ± 5 mm) was similar across all sites, but peak SWE at maximum accumulation ranged from 187 to 340 mm. Solute concentrations were highest directly under canopies, intermediate in nonshaded forest openings, and lowest in shaded forest openings. Conservative solute concentrations (SO 4 2− , R 2 = 0.80), Cl − (R 2 = 0.60), and isotope values (d 18 O R 2 = 0.96) were inversely related to SWE at maximum accumulation. Mass balance estimates of snowpack water balance using solute concentrations and isotopes indicated that sublimation ranged from <2% to ∼20% of winter precipitation, consistent with previous studies at the site. The strong relationships between solar forcing, SWE, and chemistry suggest that snow chemistry at maximum accumulation can be used to estimate overwinter sublimation. Furthermore, variability in solar forcing also can be used to refine spatial estimates of catchment solute and isotope input at melt.

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Section: Introductionsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 99%

Estimating snow sublimation using natural chemical and isotopic tracers across a gradient of solar radiation

Gustafson

Brooks

Molotch

et al. 2010

Water Resources Research

View full text Add to dashboard Cite

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“…and an area ratio of O. L corresponds to a density of about 91.6 kg m-3. These results have been confirmed in part by preliminary experimental results reported by Sommerfeld [19]. The 45°branch geometry yields an upper limit for the diffusion coefficient.…”

Section: Resultssupporting

confidence: 87%

“…The relocation of ice mass is highly localized and has been described as occurring by the "hand-to-hand" transport process [20]. When lemperature gradient metamorphism is active, the complete transition of ice crystals through the vapor phase can be completed in a time scale of 10 to 20 days [9,18,19]. This may be the most significant aspect of temperature gradient metamorphism, since the redistribution of pollutants in a snow layer may be directly affected by the movement of water vapor and the recrystallization of snow layers in a snowpack.…”

Section: Introductionmentioning

confidence: 99%

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A 2-D Microscopic Simulation of Heat and Mass Transport in Dry Snow

Christon

Burns

Sommerfeld

1990

Chemical Engineering Communications

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The problem of acid deposition and its effects on the environment is receiving increasing attention in North America and Europe. The interaction between seasonal snowcovers and deposited pollutants is of particular importance because a snowpack accumulates and stores pollutants which can ultimately be released in a rapid pulse with the first melt water in the springtime. As a direct result of an impurity pulse, water quality degrades with deleterious effects on the local environment and aquatic biological species, The timing and severity of an inpurity pulse is dependent upon the redistribution of pollutants in a snowpack which is attributed to a process known as temperature gradient metamorphism.This work investigates the influence of geometry, density and temperature on the coupled heat and mass transport in idealized, two dimensional ice lattice cells. Mass flux. concentration and temperature distributions, as well as effective diffusion coefficients and thermal conductivities are presented as functions of temperature, geometry, and density. A finite element model of the coupled, heat and mass transport is used to analyze the problem on a microscopic scale in two dimensions. Deforming meshes are used to simulate the growth/decay process which occurs over time in an ice lattice pore.The results of the analysis provide a microscale view of temperature gradient metamorphism which did not previously exist. The preferential growth of branch grains is verified using both static and dynamic computer generated images of the ice lattices undergoing temperature gradient metamorphism. It is found that the specific ice crystal geometry is determined by the thermodynamics at the solid/vapor interface. An enhancement in the effective diffusion coefficients relative to the diffusion coefficient for water vapor in dry air is observed for all the two dimensional geometries studied. A communication length on the scale of several pore lengths is found for the vapor transport through the ice lattices, and it is demonstrated that the heat and mass transfer rates are highly dependent upon the local ice lattice geometry and the snow density. KEYWORDS Snow, metamorphism thermodynamics temperature gradient. NOMENCLATURE A area (m") g; diffusion coefficient (m Z 5-1) g acceleration of gravity (m 5-2) 87 Downloaded by [University of Sydney] at 14:46 02 January 2015 88 h h sg m A k K L m P Pr q Q R Ra Ra* t T M. CHRISTON, P. BURNS AND R. SOMMERFIELD snow depth (m) latent heat of sublimation (J kg-I) mass flux rate (kg m-z S-I) thermal conductivity (W m-I°C -1 ) snow permeability (rrr') characteristic pore length (m) mass (kg) water vapor pressure (Pa) v .Prandtl Number, -ll' heat flux rate (W rn") heat transfer rate (W) ideal gas constant (J. kg-1 0K-I ) gfJ sr e Pr Rayleigh Number, Z

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Multiscale observations of snow accumulation and peak snowpack following widespread, insect‐induced lodgepole pine mortality

et al. 2012

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Seasonal snowpack in forested lands is the primary source of fresh water in western North America, where mountain pine beetle (MPB) infestation has resulted in rapid and extensive tree die‐off. Forests significantly influence the amount and spatial distribution of peak seasonal snowpack, but the impacts of large‐scale tree mortality on the processes controlling peak snowpack are not well understood. We evaluate the effects of widespread tree mortality on winter snow accumulation and peak seasonal snowpack across multiple spatial scales and several levels of MPB impact in the Central Rocky Mountains. Observations for winters 2010 and 2011 include continuous snow depths in 20 plots, distributed snow surveys at peak accumulation and climate observations above and below canopy including precipitation, temperature, humidity, wind and shortwave radiation. Stable water isotopes were observed for fresh snowfall and for snowpack. Plot‐scale snowfall observations showed 20% lower interception (p < 0.05) in grey‐phase stands (needles lost) than in unimpacted stands. However, distributed snow surveys found no differences in peak seasonal snow water equivalent between unimpacted and grey‐phase stands. Water isotopes of snowpack from MPB‐killed stands indicated kinetic fractionation; enriched values demonstrated higher winter snowpack sublimation in MPB‐killed forest. Following MPB infestation, reduced canopy sublimation of intercepted snow appeared to be compensated by increased snowpack sublimation, consistent with observations of higher snowpack insolation. Consequently, the effects of widespread tree mortality on peak seasonal snowpack, which is crucial for downstream water resources, will be influenced by compensation for lower interception by higher snowpack sublimation. Copyright © 2012 John Wiley & Sons, Ltd.

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The Fractionation of Natural Isotopes During Temperature Gradient Metamorphism of Snow

Cited by 16 publications

References 4 publications

Estimating snow sublimation using natural chemical and isotopic tracers across a gradient of solar radiation

Estimating snow sublimation using natural chemical and isotopic tracers across a gradient of solar radiation

A 2-D Microscopic Simulation of Heat and Mass Transport in Dry Snow

Multiscale observations of snow accumulation and peak snowpack following widespread, insect‐induced lodgepole pine mortality

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