Application of a Regional Model to Astronomical Site Testing in Western Antarctica (1605.07231v1)

Abstract: The quality of ground based astronomical observations are significantly affected by telluric conditions, and the search for best sites has led to the construction of observatories at remote locations, including recent initiatives on the high plateaus of E Antarctica where the calm, dry and cloud free conditions during winter are recognized as amongst the best. Site selection is an important phase of any observatory development project, and candidate sites must be tested with specialized equipment, a process both time consuming and costly. A potential screening of site locations before embarking on field testing is through the use of climate models. Here, we describe the application of the Polar version of the Weather Research and Forecast (WRF) model to the preliminary site suitability assessment of an unstudied region in W Antarctica. Numerical simulations with WRF were carried out for the winter of 2011 at 3 km and 1 km spatial resolution over a region centered on the Ellsworth mountain range. Comparison with observations of surface wind speed and direction, temperature and specific humidity at nine automatic weather stations indicate that the model succeed in capturing the mean and time variability of these variables. Credible features shown by the model include zones of high winds over the southernmost part of the Ellsworth Mntns, a deep thermal inversion over the Ronne-Fincher Ice Shelf and strong west to east moisture gradient across the entire study area. Comparison of simulated cloud fraction with a spacebourne Lidar climatology indicates that the model may underestimate cloud occurrence, a problem that has been noted in previous studies. A simple scoring system was applied to reveal the most promising locations. The results of this study indicate that the WRF model is capable of providing useful guidance during the initial site selection stage of project development.