A new method for analysing and representing ground temperature variations in cold environments. The Fuegian Andes, Tierra del Fuego, Argentina

M Oliveira,A Pérez-Alberti,F Castillo-Rodríguez,R.M Crujeiras,A Rodríguez-Casal

doi:10.18172/cig.3373

M Oliveira, A Pérez-Alberti + Show 3 more

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https://doi.org/10.18172/cig.3373

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Abstract

The thermal response of soils in cold environments has been investigated in numerous studies. The data considered here were obtained in a study carried out in Tierra del Fuego, Argentina, as part of the IV International Polar Year. Temperature sensors were installed at ground level (0) and depths of -10, -20 and -60 cm in the study area, with the aim of characterizing the thermal response by detecting diurnal and annual variations.The study has two main aims. The first is to present and discuss the study findings regarding the thermal response of a soil in a sub-Antarctic environment by using classical descriptive analysis. The second, closely related, aim is to apply some novel statistical tools that would help improve this description. The study of freeze-thaw patterns can be approached from a non-parametric perspective, while taking into account the cyclical nature of the data. Data are considered cyclical when they can be represented on a unit circle, as with the hours in which certain events occur throughout a day (e.g. freezing and thawing). Analysis of this type of data is very different from the analysis of scalar data, as regards both descriptive and graphical measures. The application in this study of methods used to represent and analyse cyclical data improved visualization of the data and interpretation of the analytical findings. The main contribution of the present study is the use of estimators of the nuclear type density and derived techniques, such as the CircSiZer map, which enabled identification of significant freeze-thaw patterns. In addition, the relationships between the temperature recordings at different points were analysed using Taylor diagrams.

Highlights

Study of the thermal response of soil is very important for understanding the functioning of the dynamics of the slopes
Significant Zero crossings of the derivative (SiZer) is based on two notions: the first is the notion of scale space whereby instead of trying to find a bandwidth that provides the closest match to the unknown true density, we examine the whole range of bandwidths and explore the different features that occur on different scales
In the context of scalar data, the relationships between temperature measurements can be illustrated by Taylor diagrams

Summary

Introduction

Study of the thermal response of soil is very important for understanding the functioning of the dynamics of the slopes. The soil temperature regime strongly influences geomorphological, hydrological and related phenomena, such as frost creep processes, needle-ice creep, shallow solifluction, upfreezing of granules (Washburn, 1979; Williams and Smith, 1989), patterned ground, solifluction sheets (cf Matsuoka, 2001) and terracettes, all of which are manifested in the active layer (Leszkiewicz and Caputa, 2004). The upper level of a soil undergoing freeze-thaw processes is called the active layer, which has been defined as “the layer of ground above permafrost which thaws in summer and freezes again in winter” (Muller, 1947). As the same author defined frozen ground as “ground that has a temperature of 0oC or lower” (Muller, 1947), the definition of the active layer can, unequivocally, be interpreted in terms of temperature. The depth of thaw penetration, or the active-layer thickness (ALT), in permafrost-affected soils mainly depends on the intensity and duration of the cold, snow cover, vegetation, soil texture, rock type, permafrost continuity, precipitation and cloud cover (Goodrich, 1982; French, 2013; Guglielmin et al, 2003)

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