Regime térmico da camada ativa e pemafrost na Península de Keller, Ilha Rei George, Antártica (2011-2014)

Abstract

The monitoring of soil thermal regime in periglacial environment is critical to identify the presence of permafrost and the thickness of the active layer. This study was conducted to identify factors that influence the soil thermal regime in Keller Peninsula, from 02/2011 to 02/2015. For such monitoring were installed air temperature sensors (Tar) and soil (Ts) and soil moisture at different depths and sites in Keller Peninsula. Preliminary analyzes of the data were based on the monthly average, annual; maximum and minimum averages and seasonal averages of Tar; Ts and soil moisture at different depths in the monitoring sites Ipanema Refúgio II, Punta and site soil with Standard. After these analyzes identified the days of freezing, thawing, isothermal and freezing / thawing for each depth; the frequency distribution of temperature and temperature fluctuation during the period studied. The analyzes were carried out: the cross-correlation between the AAO series (Antarctic Oscillation Index), SOI (Southern Oscillation Index), Tar and Ts; linar simple regression between the annual average temperatures and the highest average maximum and annual minimum; Multiple linear regression between moisture apparent soil thermal difuvividade (DTA); N_fator the rate of freezing and its relationship with DTA and; the harmonic analysis of the AAO series, SOI, MEI (multivariate ENSO index), Tar and Ts. The highest and lowest Tar annual average in the four years and four sites studied was 1.7 °C on site Refúgio II and 4.8 °C in place with Standard Solo, respectively. The period in which the soil has more time under the active layer system was Ipanema and Refúgio II. The highest and the lowest sum of degree days of thawing and freezing were 154.6 and 263.3, respectively Refúgio II In cross-correlation analysis the delay phase between the waves of Tar and Ts was less than one month in all sites. The correlation between the AAO x Tar Tar and SOI x occurs up to 5 months delay between the phases. Simple linear regression analysis indicated that in Ipanema and Refúgio II, the soil thermal regime restricted the active layer. On site soil with Standard and Punta Plaza thermal regime presented reached the permafrost before the layer of 0.80 and 1.00 m deep respectively. In the frequency histograms showed predominance of temperatures around 0 °C and the first difference graph shown that temperature variations are stronger in summer. Multiple linear regrassão analysis showed that the moisture influence on the DTA in most cases. The freezing N_fator was inversely proportional to close DTA the surface, but when compared with the DTA in depth the relationship approaches. The harmonic analysis identified that climate variability in ways that influenced the Tar these sites between the years 2011-2014, were the AAO and SOI indices. In general, the thermal insulation provided by covering the thickest snow in places Punta Plaza and Solo with Standard allowed the permafrost were found at depths less when compared to the Refúgio II and Ipanema sites that were less thick blanket of snow.