/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Geotechnical Journal, 19, pp. 421-432, 1982 The influence of snow cover on the ground thermal regime Goodrich, L. E. This a r resents the results of a numerical study of the effects of snow cover on long-term, periodic, steady-state equilibrinm -ground emperatures. It is shown that mean annual ground temperatures decrease with depth when the soil thermal conductivity is greater in the frozen than in the unfrozen phase. For permafrost conditions the increase in mean annual ground temperatures due to seasonal snow cover is augmented significantly when soil latent heat is present. In seasonal frost cases the calculated depth of frost penetration is extremely sensitive to details of the snow cover buildup. In permafrost cases calculated mean annual temperatures are extremely sensitive to the assumptions made in treating the snow cover. In either case, because it is difficult to model snow cover accurately, the reliability of ground thermal regime computations is adversely affected. Keywords: ground thermal regime, ground temperatures, soil temperatures, numerical model, finite difference, snow cover. Introduction description of Lachenbruch to include a sinusoidal time The influence of seasonal snow cover on the annual dependence for the thermal properties of the surface. In ground thermal regime has long been recognized. Snow addition, a simplified numerical model was used to cover is an insulator by comp~son with most natural examine the effects of introducing soil latent heat. ground surface materials and, since it is present only The Parameter sensitivity study presented here was during the cold part of the annual temperature cycle, the made with a somewhat more elaborate numerical model, net effect over a year is to raise mean annual ground which has been described in detail elsewhere (Goodrich temperatures, often by several degrees. 1974,1978). A brief description is given in Appendix B. hi^ paper describes a numerical study of snow-Conclusions similar to those of Gilpin and Wong (1976) ground thermal interactions and presents a series of are reached regarding the effects of soil latent heat. A graphical results that illustrate the effect on the long-number of aspects the snOw-ground term ground thermal regime of variations in snow and thermal interaction are discussedsoil properties. These calculations originally formed a part of the author's Ph.D. thesis (Goodrich 1976), work CanadianModel assumptions done in the early 19...

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Geotechnical Journal, 24, 1, pp. 160-63, 1987-02 Measurement of soil water content using the combined time-domain reflectometry -thermal conductivity probe Baker, T. H. W.; Goodrich, L. E. A two-pronged metal probe measures the thermal conductivity and apparent dielectric constant of soils in the laboratory and in the field. One prong acts as a transient line heat source probe in measuring thermal conductivity. The apparent dielectric constant of the soil is determined by the time-domain reflectometry (TDR) technique, using both prongs as a parallel transmission line. Volumetric water content is determined from the apparent dielectric constant, making use of an empirical relation valid for most soils. For volumetric water contents above about 8%, the apparent dielectric constant shows a strong dependence on water content and relatively small changes can be measured; sensitivity increases with water content. For volumetric water contents less than 8%, a soil-dependent empirical relation between water content and thermal conductivity has been developed that is most sensitive at lower water contents. The combined probe provides a means of monitoring the water content of soils over a wide range of values, in the field and in the laboratory. CanadianKey words: soil water content, time-domain reflectometry, thermal conductivity.Une sonde a double pointe mesure la conduction thermique et la constante diklectrique apparente des sols en le laboratoire et sur le terrain. Une pointe agit comme une source de ligne de chaleur transitoire pour mesurer la conductivite thermique. La constante diklectrique apparente du sol reste determinee par une technique de rkflectometrie en fonction du temps (TDR), utilisant les deux pointes comme ligne de transmission. La teneur en eau volumetrique est determinee en partant de la constante dielectrique apparente, au moyen d'une relation empirique valable pour la plupart des sols. Pour les teneurs en eau volumktriques supt5rieures a environ 8%, la constante dielectrique apparente depend fortement de la teneur en eau, et des changements relativement faibles peuvent &tre mesurks; la sensibilite augmente avec la teneur en eau. Pour les teneurs en eau volumktriques infkrieures a 8%, une relation empirique fonction du sol a Ct k dkveloppCe entre la teneur en eau et la conductivite thermique; cette relation est tres sensible aux teneurs en eau plus faibles. La sonde fournit un moyen de mesurer de facon continu...