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Titolo:
Non-conductive heat transfer associated with frozen soils
Autore:
Kane, DL; Hinkel, KM; Goering, DJ; Hinzman, LD; Outcalt, SI;
Indirizzi:
Univ Alaska Fairbanks, Water & Environm Res Ctr, Fairbanks, AK 99775 USA Univ Alaska Fairbanks Fairbanks AK USA 99775 Ctr, Fairbanks, AK 99775 USA Univ Cincinnati, Dept Geog, Cincinnati, OH 45221 USA Univ Cincinnati Cincinnati OH USA 45221 pt Geog, Cincinnati, OH 45221 USA Univ Alaska Fairbanks, Dept Mech Engn, Fairbanks, AK 99775 USA Univ AlaskaFairbanks Fairbanks AK USA 99775 ngn, Fairbanks, AK 99775 USA
Titolo Testata:
GLOBAL AND PLANETARY CHANGE
fascicolo: 3-4, volume: 29, anno: 2001,
pagine: 275 - 292
SICI:
0921-8181(200106)29:3-4<275:NHTAWF>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
NEAR-SURFACE PERMAFROST; ACTIVE LAYER; WATER-MOVEMENT; CENTRAL ALASKA; SNOW COVER; HYDROLOGY; REGIME; CANADA; TUNDRA; BASIN;
Keywords:
non-conductive heat transfer; soils; infiltration; convection; phase change; climate;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
51
Recensione:
Indirizzi per estratti:
Indirizzo: Kane, DL Univ Alaska Fairbanks, Water & Environm Res Ctr, Fairbanks, AK 99775 USA Univ Alaska Fairbanks Fairbanks AK USA 99775 banks, AK 99775 USA
Citazione:
D.L. Kane et al., "Non-conductive heat transfer associated with frozen soils", GLOBAL PLAN, 29(3-4), 2001, pp. 275-292

Abstract

The assertion that pure conductive heat transfer always dominates in cold climates is at odds with decades of research in soil physics which clearly demonstrate that non-conductive heat transfer by water and water vapor are significant, and frequently are for specific periods the dominant modes of heat transfer near the ground surface. The thermal regime at the surface represents the effective boundary condition for deeper thermal regimes. Also,surface soils are going to respond more quickly to any climatic fluctuations; this is important to us because most facets of our lives are tied to earth's surface. To accurately determine the surface thermal regime (for example, the detection of climate change), it is important to consider all potential forms of heat transfer. Gradients that have the potential to alter the thermal regime besides temperature include pore water pressure, gravitational, density, vapor pressure and chemical. The importance of several non-conductive heat transport mechanisms near the ground surface is examined. Infiltration into seasonally frozen soils and freezing (release of latent heat) of water is one mechanism for the acceleration of warming in surficial soils in the spring. Free convection due to buoyancy-induced motion of fluids does not appear to be an important heat-transfer mechanism; estimates of the Rayleigh number (the ratio of buoyancy to viscous forces) are generally around 2, which is too low for effective heat transfer. The Peclet number (ratio of convective to conductive heat transfer) is on the order of 0.25 for snowmelt infiltration and up to 2.5 for rainfall infiltration for porous organic soils. In mineral soils, both vertical and horizontal advectionof heat can be neglected (Peclet number is approximately 0.001) except forsnowmelt infiltration into open thermal contraction cracks. The migration of water in response to temperature or chemical,gradients from unfrozen soil depths to the freezing front, and the redistribution of moisture within the frozen soil from warmer depths to colder depths, can also result in heattransfer although this effect has not been quantified here. Many of these processes are seasonal and effective only during periods of phase change when the driving gradient near the ground surface is relatively large. (C) 2001 Elsevier Science B.V. All rights reserved.

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Documento generato il 04/08/20 alle ore 02:11:03