Pan-Antarctic map of near-surface permafrost temperatures at 1 km2 scale

• Main Authors: Obu, Jaroslav, Westermann, Sebastian, Vieira, Gonçalo, Abramov, Andrey, Balks, Megan, Bartsch, Annett, Hrbáček, Filip, Kääb, Andreas, Ramos, Miguel
• Format: Text
• Language: English
• Published: 2019
• Subjects: Antarctic; Markham; Mount Markham; Queen Elizabeth Range; The Antarctic; Transantarctic Mountains; Antarc*; Ice; Ice Sheet; permafrost
• Online Access: https://doi.org/10.5194/tc-2019-148; https://www.the-cryosphere-discuss.net/tc-2019-148/

Permafrost is present under almost all of the Antarctic’s ice-free areas but little is known about spatial variations of permafrost temperatures outside a few areas with established ground temperature measurements. We modelled a temperature at the top of the permafrost (TTOP) for all the ice-free areas of Antarctic mainland and Antarctic Islands at 1 km 2 resolution during 2000–2017. The model was driven by remotely-sensed land surface temperatures and down-scaled ERA-Interim climate reanalysis data and subgrid permafrost variability was simulated by variable snow cover. The results were validated against in-situ measured ground temperatures from 40 permafrost boreholes and the resulting root mean square error was 1.9 °C. The lowest near-surface permafrost temperature of −33 °C was modelled at Mount Markham in Queen Elizabeth Range in the Transantarctic Mountains. This is the lowest permafrost temperature on Earth according to the modelling results on global scale. The temperatures were most commonly modelled between −23 and −18 °C for mountainous areas rising above the Antarctic Ice Sheet and between −14 and −8 °C for coastal areas. The model performance was good where snow conditions were modelled realistically but errors of up to 4 °C can occur at sites with strong wind-driven redistribution of snow.