Monitoring of climate variability and permafrost active layer on James Ross Island, Maritime Antarctica
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|Permafrost and glaciers belong to key indicators of climate change as they react sensitively to climate variations. Monitoring the climate variability, thermal regime and thickness of the permafrost active layer is especially important in polar regions, which experience a rapid increase in average temperature of the air . The largest warming in the Southern Hemisphere over the last 50 years was reported from the western side of Antarctic Peninsula. However, field evidence of meteorological and cryospheric environmental variables is limited due to difficult accessibility and expensive logistics. The Ulu Peninsula in the northern part of James Ross Island represents a suitable locality for investigations of these variables and their interrelationship, as it is one of the largest deglaciated areas along the Antarctic Peninsula. Since 2007, an integrated multidisciplinary study of terrestrial ecosystems has been carried out at the Johann Gregor Mendel Station (63°48'S, 57°53'W). In this contribution, preliminary results of microclimate measurements and active layer monitoring on the Ulu Peninsula are presented. Climate conditions of this region are characterized by a short summer (December-February) with positive air temperatures up to 8°C and annual mean air temperature around -7°C. In spite of high cloudiness (daily means of 80– 90 %), global solar radiation can reach the maxima as high as 30 MJ.m-2 on clear sky days around summer solstice. Mean annual ground temperatures (MAGT) range from -6.2°C (200 cm) to - 6.6°C (5 cm) near by the Mendel Station. MAGT at Johnson Mesa (~320 m a.s.l.) varies from -8.0 °C (50 cm) to -8.5 °C (5 cm), which confirms the strong dependence of the sites on altitude. The active layer thickness was recorded at the depth of about 55-60cm (Mendel Station) and/or 25-30 cm (Johnson Mesa) at the end of January. The effect of air temperature and global radiation on ground temperature was studied with respect to the site characteristics and snow occurrence. The correlation analysis showed that the highest influence of the air temperature on the ground temperature was observed in days without snow cover during winter season. Conversely, the significant decrease of the air temperature influence was found in days with snow cover higher than 7 cm and/or in days without snow cover during summer. Acknowledgements: The authors thank CzechPolar infrastructure for providing facilities.