title: Active layer and permafrost thermal regime in a patterned ground soil in Maritime Antarctica, and relationship with climate variability models.
abstract: Permafrost and active layer studies are important to understand and predict regional climate changes. The objectives of this work were: i) to characterize the soil thermal regime (active layer thickness and permafrost formation) and its interannual variability and ii) to evaluate the influence of different climate variability modes to the observed soil thermal regime in a patterned ground soil in Maritime Antarctica. The study was carried out at Keller Peninsula, King George Island, Maritime Antarctica. Six soil temperatures probes were installed at different depths (10, 30 and 80cm) in the polygon center (Tc) and border (Tb) of a patterned ground soil. We applied cross-correlation analysis and standardized series were related to the Antarctic Oscillation Index (AAO). The estimated active layer thickness was approximately 0.75cm in the polygon border and 0.64cm in the center, indicating the presence of permafrost (within 80cm). Results indicate that summer and winter temperatures are becoming colder and warmer, respectively. Considering similar active layer thickness, the polygon border presented greater thawing days, resulting in greater vulnerability to warming, cooling faster than the center, due to its lower volumetric heat capacity (Cs). Cross-correlation analysis indicated statistically significant delay of 1day (at 10cm depth) in the polygon center, and 5days (at 80cm depth) for the thermal response between atmosphere and soil. Air temperature showed a delay of 5months with the climate variability models. The influence of southern winds from high latitudes, in the south facing slopes, favored freeze in the upper soil layers, and also contributed to keep permafrost closer to the surface. The observed cooling trend is linked to the regional climate variability modes influenced by atmospheric circulation, although longer monitoring period is required to reach a more precise scenario.
authors.affiliation: Instituto Federal do Rio de Janeiro, Campus Pinheiral, 27197-000 Pinheiral, Rio de Janeiro, Brazil. Electronic address: daniela.chaves@ifrj.edu.br.
authors.forename: D A
authors.initials: DA
authors.lastname: Chaves
authors.affiliation: Departamento de Ciências Ambientais, Instituto de Florestas, Universidade Federal Rural do Rio de Janeiro, 23851-970 Seropédica, Rio de Janeiro, Brazil. Electronic address: gblyra@ufrrj.br.
authors.forename: G B
authors.initials: GB
authors.lastname: Lyra
authors.affiliation: Departamento de Solos, Universidade Federal de Viçosa, 36570-000 Viçosa, Minas Gerais, Brazil. Electronic address: marcio.francelino@gmail.com.
authors.forename: M R
authors.initials: MR
authors.lastname: Francelino
authors.affiliation: Departamento de Engenharia, Universidade Federal Rural do Rio de Janeiro, 23851-970 Seropédica, Rio de Janeiro, Brazil. Electronic address: irriga@ufrrj.br.
authors.forename: Ldb
authors.initials: L
authors.lastname: Silva
authors.affiliation: Departamento de Solos, Universidade Federal de Viçosa, 36570-000 Viçosa, Minas Gerais, Brazil. Electronic address: andre.thz@gmail.com.
authors.forename: A
authors.initials: A
authors.lastname: Thomazini
authors.affiliation: Departamento de Solos, Universidade Federal de Viçosa, 36570-000 Viçosa, Minas Gerais, Brazil. Electronic address: carlos.schaefer@ufv.br.
authors.forename: Cegr
authors.initials: C
authors.lastname: Schaefer
keywords: Antarctic oscillation mode (AAO); Climate variability; Cryosols; Polygonal soils; Soil thermal regime; Southern oscillation mode (SOI)