Ground surface temperature (GST), active layer and permafrost monitoring in continental Antarctica

Active layer and permafrost monitoring at two sites in Northern Victoria Land, Boulder Clay (74 degrees 44'45"S-164 degrees 01'17"E at 205 m a.s.l.) and Oasi (74 degrees 42'S-164 degrees 06'E at 80m a.s.l.), have been undertaken since 1996. Active layer monitoring was performed at Boulder Clay by probing on a 100 x 100 m grid following the CALM protocol, and by temperature measurements to ascertain the maximum depth of the 0 degrees C isotherm. Automatic and year-round recording of ground temperatures and of the main climatic parameters was carried out near the grid. Since 1999, ground temperatures have been monitored in a 15.5 m borehole at Oasi. The depth of the 0 degrees C isotherm correlates well with climate because the thermal offset is small, averaging less than 0.5 degrees C. The large spatial and temporal variability of its depth mainly reflects the snow accumulation pattern. Future efforts to extend the monitoring network in continental Antarctica may combine annual measurements of the maximum 0 degrees C isotherm depth with year-round monitoring of ground temperature at selected points of standardised CALM grids