Analyses on the air and snow temperatures near ground with observations of an AWS at Dome A, the summit of Antarctic Plateau

As the summit of the Antarctic Plateau, Dome A has been received international attentions. In this paper, observational data of an automatic weather station (AWS) at Dome A in 2005–2007 were used to analyze the seasonal variations of air temperatures near the ground and snow temperatures within a depth of 10 m. Analyses on the air temperatures show a typical feature of the coreless winter, and strong inversion maintains during the long winter. Accordingly the stratification near the ground is dominated by the near-neutral stable states. Seasonal fluctuations of the snow temperature decrease in amplitude and lag in phase with depth increasing, which leads to distinct seasonal temperature profiles within the depth of 10 m. Measurements show the mean annual air temperature near ground is about 5°C higher than the 10 m firn temperature due to the strong inversion near the ground. However, our estimation of the annual mean of air temperature at the ground based on the boundary layer theory is close to the mean 10 m firn temperature. The lowest air temperature (–82.7°C) currently measured at the Dome A is not the lowest one ever recorded in Antarctica, but the extremely low mean 10 m firn temperature (–58.2°C) indicates very low ground temperature. Given the prominent inversion near the ground, it is expected that Dome A might house the lowest ground temperature on the planet.