Estimation of behavior of optical turbulence during summer in the surface layer above the Antarctic Plateau using the Polar WRF model

Abstract

An optical turbulence ($C_n^2$) was found to be concentrated predominantly in the thin surface layer (SL) above the Antarctic Plateau. We present an estimation of the behavior of the SL $C_n^2$ during the summer time over the entire Antarctic Plateau, using the polar-optimized version of the Weather Research and Forecast model (Polar WRF) coupled with the Monin-Obukhov similarity theory. The results show that the $C_n^2$ is affected by the sunlight direction and terrain height. The $C_n^2$ minimum occurs sometime around the morning and evening transitions, when the condition of neutral stability is achieved inside the SL. These $C_n^2$ minima may be attributed to the relatively weaker thermal convection resulting from a small temperature difference. The simulated $C_n^2$ data coincide well with the measurements taken at the Antarctic Taishan Station using a micro-thermometer and sonic anemometer; the data are also in agreement with the seeing values obtained from a differential image motion monitor. In addition, the Polar WRF captured the $C_n^2$ minimum more precisely compared to the standard WRF.