Abstract
AbstractDry permafrost - ground with temperature always below 0°C and containing negligible ice - overlying ice-cemented ground has been reported in the Dry Valleys of Antarctica and on Mars. Here we report on a new site (79°49.213'S, 83°18.860'W, 718 m elevation) located on the side of Mount Dolence in Ellsworth Land, Antarctica. Year-round temperature and humidity measurements indicate that dry permafrost is present between depths of 13.5 and 49.0 cm - the location of ice-cemented ground. The mean annual frost point of the ice-cemented ground is -17.0 ± 0.2°C and the mean annual frost point of the atmosphere is -22.7 ± 1°C. The corresponding mean annual temperatures are -19.2°C and -20.3°C. Neither the temperature of the ice-cemented ground nor the air rise above freezing. Both the dry permafrost and the ice table may be habitable. In the dry soil at 3 cm depth there are 80 hours in the summer when temperature exceeds -5°C and water activity exceeds 0.8. At the ice table, temperature exceeds -10°C and water activity exceeds 0.8 for 35 hours in the year. The ice table and the dry permafrost above it would be considered a ‘Special Region’ on Mars. Further microbial investigation of this site is indicated.
Highlights
Dry permafrost is ground that never warms above 0°C and has negligible ice content
Dry permafrost overlying ice-cemented ground is rare on Earth, but is widespread on Mars
In the polar regions of Mars, the dry permafrost layer begins at the surface and ice-cemented ground is found below it (Mellon & Jakosky 1993, Mellon et al 2009, Smith et al 2009)
Summary
Dry permafrost is ground that never warms above 0°C and has negligible ice content. Dry permafrost overlying ice-cemented ground is rare on Earth, but is widespread on Mars. In the polar regions of Mars, the dry permafrost layer begins at the surface and ice-cemented ground is found below it (Mellon & Jakosky 1993, Mellon et al 2009, Smith et al 2009). On Earth, dry permafrost over ice-cemented ground has been reported in the arid upland regions of the Antarctic Dry Valleys (Campbell & Claridge 2006, Bockheim et al 2007). In an early year-round monitoring study of dry permafrost at Linnaeus Terrace in Upper Wright Valley at an elevation of 1600–1650 m, McKay et al (1998) found that maximum soil temperatures exceeded 0°C to a depth of 12.5 cm, dry permafrost extended from that depth to 25 cm and ice-cemented soil was present below that level.
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