Identification

Title

Snow temperature changes within a seasonal snowpack and their relationship to turbulent fluxes of sensible and latent heat

Abstract

Snowpack temperatures from a subalpine forest below Niwot Ridge, Colorado, are examined with respect to atmospheric conditions and the 30-min above-canopy and subcanopy eddy covariance fluxes of sensible Qh and latent Qe heat. In the lower snowpack, daily snow temperature changes greater than 1°C day⁻¹ occurred about 1-2 times in late winter and early spring, which resulted in transitions to and from an isothermal snowpack. Though air temperature was a primary control on snowpack temperature, rapid snowpack warm-up events were sometimes preceded by strong downslope winds that kept the nighttime air (and canopy) temperature above freezing, thus increasing sensible heat and longwave radiative transfer from the canopy to the snowpack. There was an indication that water vapor condensation on the snow surface intensified the snowpack warm-up. In late winter, subcanopy Qh was typically between −10 and 10 W m⁻² and rarely had a magnitude larger than 20 W m⁻². The direction of subcanopy Qh was closely related to the canopy temperature and only weakly dependent on the time of day. The daytime subcanopy Qh monthly frequency distribution was near normal, whereas the nighttime distribution was more peaked near zero with a large positive skewness. In contrast, above-canopy Qh was larger in magnitude (100–400 W m⁻²) and primarily warmed the forest–surface at night and cooled it during the day. Around midday, decoupling of subcanopy and above-canopy air led to an apparent cooling of the snow surface by sensible heat. Sources of uncertainty in the subcanopy eddy covariance flux measurements are suggested. Implications of the observed snowpack temperature changes for future climates are discussed.

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document

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http://n2t.net/ark:/85065/d70p10zz

codeSpace

Dataset language

eng

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geoscientificInformation

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title

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reference date

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publication

effective date

2016-01-01T00:00:00Z

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publication

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2014-02-01T00:00:00Z

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Copyright 2014 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.

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OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

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pointOfContact

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