Comparison of the atmosphere above the South Pole, Dome C and Dome A: first attempt

TL;DR

This study compares atmospheric conditions above Dome C, Dome A, and the South Pole on the Antarctic Plateau, assessing their suitability for astronomy through ECMWF analyses and radiosoundings, revealing stability differences and wind profiles.

Contribution

It provides the first comparative analysis of atmospheric stability and wind conditions above these Antarctic sites using ECMWF data and radiosoundings.

Findings

Antarctic sites are generally more stable than mid-latitude sites.

Dome C exhibits worse thermodynamic instability than South Pole and Dome A.

Wind speed and shear vary significantly among the sites.

Abstract

The atmospheric properties above three sites (Dome C, Dome A and the South Pole) on the Internal Antarctic Plateau are investigated for astronomical applications using the monthly median of the analyses from ECMWF (the European Centre for Medium-Range Weather Forecasts). Radiosoundings extended on a yearly time scale at the South Pole and Dome C are used to quantify the reliability of the ECMWF analyses in the free atmosphere as well as in the boundary and surface layers, and to characterize the median wind speed in the first 100 m above the two sites. Thermodynamic instability properties in the free atmosphere above the three sites are quantified with monthly median values of the Richardson number. We find that the probability to trigger thermodynamic instabilities above 100 m is smaller on the Internal Antarctic Plateau than on mid-latitude sites. In spite of the generally more stable atmospheric conditions of the Antarctic sites compared to mid-latitude sites, Dome C shows worse thermodynamic instability conditions than those predicted above the South Pole and Dome A above 100 m. A rank of the Antarctic sites done with respect to the strength of the wind speed in the free atmosphere (ECMWF analyses) as well as the wind shear in the surface layer (radiosoundings) is presented.