Abstract
Heat transfer process in the soil active layer is important for the knowledge of its thermal properties linked with climate issues. The objective of this work was to analyze the energy flux in different soil profiles by estimating the apparent soil thermal diffusivity ($ATD$). The study was carried out in Keller Peninsula, located at King George Island in four different sites differing by soil characteristics, as well as vegetation coverage and landscape setting. The $ATD$ was estimated in function of the long-term hourly temperature records at different soil depths. In addition, we estimated the seasonal mean of the $ATD$ and the freezing $N$-factor. Results showed that $ATD$ values were smaller at shallow depths and increased with depth. The diffusivity values presented lower variability in colder conditions, especially at deeper soil layers. Water content was the main factor affecting soil thermal diffusivity at sites $1$ and $3$ (more than $70$ and $63\%$ of probability). At sites $3$ and $4$ lower $N$-factors were observed, suggesting higher snow pack and permafrost closer to the soil surface. Hence, positive $ATD$ appears in the summer due to thawing increases soil moisture, while negative $ATD$ appears during the freeze of the snow pack and precipitation.
Highlights
Studies of climate monitoring have been increasingly explored in order to obtain information about the origin and trends of the several climate variables, such as temperature
Positive apparent soil thermal diffusivity (ATD) appears in the summer due to thawing increases soil moisture, while negative ATD appears during the freeze of the snow pack and precipitation
The diffusivity tends to infinity when soil temperature values closer or in the isothermal status, as the denominator of eq 1 approaches zero. Based on this restriction and the accuracy of the sensors, we decided to disregard the values of the temperature variation between –0.04oC and +0.04oC
Summary
Studies of climate monitoring have been increasingly explored in order to obtain information about the origin and trends of the several climate variables, such as temperature. The soil active layer and permafrost are highly sensitive to climate warming, being important for regulating energy flow and acting as indicators of the current climate trends. The energy flux in soils is the focus of many studies and is recognized as the main component for understanding climate variability at local levels (Almeida et al 2014). Several factors influence the heat transfer processes in the active layer as well as thermal properties of the soil, including soil temperature, moisture and granulometry (stoniness). The snow cover and vegetation act as insulators or buffers, depending on the structure, density and thickness of soil coverage (Almeida et al 2014). The processes of energy transfer between soil and air are more effective in environments with little snow and vegetation coverage. Seasonal coverage of snow during the freezing season may increases the annual average of soil temperature at the surface, causing permafrost
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