Summer evolution of the active layer thickness in Cerro de la Cruz area (Deception Island, Maritime Antarctic).

BATISTA,V., M. NEVES, R. MELO, G. VIEIRA, A. CASELLI, M. RAMOS

Oslo

Conferencia; International Polar Year Oslo Open Science Conference,; 2010

SCAR

In order to understand the influences of altitude and aspect on active layer thickness, 6 small CALM sites were installed in Deception Island. These allow for monitoring the spatial and temporal evolution of thaw during the summer and provide a insight into the characteristics of active layer and permafrost in this island. Each small CALM site consists of a square limiting a grid of 9 monitoring points. The measurement of the active layer thickness was made using a metal probe inserted into the soil down to the frozen ground. The depth at each node was recorded and average data for each small CALM site were analised. Observations were made at a few days interval during the summers of 2009 and 2010. The chosen area shows non-cohesive volcano-sedimentary substratum and slopes with various aspects and altitudes. Four small CALM sites were installed at different altitudes at a north facing slope allowing to evaluate its influence on thaw, but allowing for similar incoming solar radiation. Two small CALM sites have been located on the north and south slopes of an elongated E-W running interfluve. Chosen sites were at similar altitude, but showed different aspects allowing for contrasting incoming radiation. This poster presents the results for 2009 and 2010 and an evaluation of the influence of altitude and aspect in the behavior of the active layer. Data are compared to meteorological data from a nearby station. Interesting results were obtained on the rates thaw according to altitude and aspect. During the summer, events with lower air temperatures resulted in a upwards refreezing that lasted for very short periods before the reinitiation of thaw.