[1] The current permafrost distribution on Livingston Island, South Shetland Islands, maritime Antarctic, was investigated using electrical resistivity tomography, refraction seismics, and shallow borehole temperatures. The field sites include different geological and geomorphological settings, including ice cored moraines and bedrock sites with debris covers of different thickness. Two-dimensional geophysical inversion schemes were used to analyze spatial heterogeneity at field sites and to detect isolated occurrences of ground ice. Results confirm that permafrost is widespread on Livingston Island, with high ice content in ice cored moraines and little in the cracks and fissures of frozen bedrock. Specific electrical resistivity values range from 10,000-40,000 ohm-m (frozen unconsolidated material) to 1500-10,000 ohm-m (frozen quartzite/shale). Combining seismic P wave velocities and specific electrical resistivities, a typical ''roof-type'' distribution was found with maximum resistivities coinciding with P wave velocities around 3000 m/s and decreasing resistivities for both increasing and decreasing velocities.

Abstract:In order to monitor the evolution of the active layer in the South Shetland Islands, in February 2009 we established a new Circumpolar Active Layer Monitoring (CALM) site in the Limnopolar Lake basin on Byers Peninsula, Livingston Island. We monitored air, surface and ground (two boreholes of 135 and 80 cm deep) temperatures and Active Layer Thickness (ALT) was measured by mechanical probing in early February 2009, 2010 and 2011. The mean ALT was 44 cm with a range of about 92 cm, but where permafrost existed it was deeper than 1.0 m, as could be inferred from the borehole temperatures. ALT at this site was very dependent on air temperature and snow cover thickness, the ALT spatial distribution presenting the same pattern as soil penetration resistance, and higher values ALT coinciding with sites where patterned ground, ponds, and a near surface ground water saturation were observed. Additionally, ground temperature data provided an excellent tool for understanding the relationship between the ALT measured during the thaw season and the thermal evolution of the ground throughout the year.

This paper describes results obtained from scientific work and experiments performed on Livingston and Deception Islands. Located in the South Shetland Archipelago, these islands have been some of the most sensitive regions over the last 50 years with respect to climate change with a Mean Annual Air Temperature (MAAT) close to -2 ºC. Three Circumpolar Active Layer Monitoring (CALM) sites were installed to record the thermal regime and the behaviour of the active layer in different places with similar climate, but with different soil composition, porosity, and water content. The study's ultimate aim is to document the influence of climate change on permafrost degradation. Preliminary results, obtained in 2006, on maximum active-layer thickness (around 40 cm in the CALM of Deception Island), active layer temperature evolution, snow thickness, and air temperatures permit early characterization of energy exchange mechanisms between the ground and the atmosphere in the CALM-S sites.

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This paper examines the short- and mid-term periodicities (≲2 yr) in the cosmic-ray flux along 55 yr, from 1964 to 2019. The cosmic-ray flux has been computed by averaging the counting rates, in typified units, of a set of selected neutron monitors. This builds a representative virtual neutron monitor, named the global neutron monitor. The relevant discovered periodicities are ∼13.5, ∼27, ∼46–64, ∼79–83 day; Rieger-type (∼134–190 days); ∼225–309 day; and ∼1.06–1.15, ∼1.31–1.40, and ∼1.75–2.20 yr periods. The same analyses have been applied to the sunspot number (SSN) with the aim to compare the discovered periodicities and look for possible origins of these periodicities. Two main results have been achieved: the periodicities of 77–83 days, 134–190 days (Rieger type), 225–309 days, ∼1.3 yr, and ∼1.7 yr could be related to the solar dynamo, and an inversely linear relationship has been found between the average of the SSN versus the duration time for each solar cycle of the ∼1.75–2.20 yr period.