Estimating optical turbulence of atmospheric surface layer at Antarctic Taishan station from meteorological data

Abstract

Turbulence intensity in the near-surface layer and its decrease rate with height are closely related to the quality of potential sites. Astronomers have been pursuing a perfect astronomical site to place the large-aperture telescopes. Compared with the best mid-latitude sites, Antarctic plateau inevitably becomes an ideal site for building the next-generation large optical and infrared telescopes, which is because of its low infrared sky emission, low atmospheric precipitable water vapour content, low aerosol and dust content of the atmosphere, and light pollution. In this paper, we establish a model of the atmospheric optical turbulence in surface layer, and use it to estimate Cn2 at Antarctic Taishan station for the first time. The meteorological parameters of the model input are the data measured by a mobile atmospheric parameter measurement system at Antarctic Taishan station from 30 December 2013 to 10 February 2014. The values of Cn2, estimated by the model and measured by a micro-thermometer, are compared. Sensitivity analysis of the estimation method is also carried out. The measurement results and analyses show that Cn2 obtained at Taishan station has obvious diurnal variation characteristics, with well-behaved peaks in the daytime and nighttime, and minima near sunrise and sunset. Cn2 obtained in the nighttime is stronger than that in daytime, more specifically, it is on the order of 210-14 m-2/3. The comparison between model predictions and experimental data demonstrates that it is feasible to estimate Cn2 in Antarctic by using this model. The biggest differences between Cn2 values obtained from the model and measurement usually emerge at sunrise and sunset, respectively. Considering the fact that Antarctic atmosphere is in a stable state most of the time, the values of Cn2 estimated by different nondimensional structure parameter functions are nearly the same. Thus, the measurement accuracy of air temperature difference from one height to another is the main factor that affects the estimated value of Cn2.