Application of a regional model to astronomical site testing in western Antarctica

Abstract

Abstract. The quality of ground based astronomical observations are significantly affected by local atmospheric conditions, and the search for the best sites has led to the construction of observatories at increasingly remote locations, including recent initiatives on the high plateaus of East Antarctica where the calm, dry and cloud free conditions during winter are recognized as amongst the best in the world. Site selection is an important phase of any observatory development project, and candidate sites must be tested in the field with specialized equipment, a process both time consuming and costly. A potential means of screening site locations before embarking on field testing is through the use of regional climate models (RCM). In this study we describe the application of the Polar version of the Weather Research and Forecast (WRF) model to the preliminary site suitability assessment of a hitherto unstudied region in West Antarctica.Numerical simulations with WRF were carried out for the winter (MJJA) 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 performed well in capturing the mean values and time variability of these variables. Credible features revealed by the model include zones of high winds over the southernmost part of the Ellsworth Mountains, 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 CALIPSO 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.

Meteorological Data from KLAWS-2G for an Astronomical Site Survey of Dome A, Antarctica

“…Mast-based automated weather stations (AWS), such as KLAWS, with multiple sensors at different elevations are important for site evaluation. Not only can a mast AWS give direct information on the atmospheric turbulence and wind speed below the boundary layer (HU14), it can also provide crucial data for site simulations (Falvey & Rojo 2016). Moreover, it has helped us to operate unattended telescopes (Shang et al 2012;Liu et al 2018) at DomeA, and the data are also useful for designing and building large diameter telescopes with adaptive optics systems (Aristidi et al 2005) in the future.…”

Wind Energy Exploration over the Atacama Desert: A Numerical Model–Guided Observational Program

“…This is most probably due to the particularly extreme dryness and absence of vegetation over much of the Atacama compared to other desert regions worldwide. Interestingly, lessons learned in configuring the WRF Model for the drainage winds over the Atacama Desert aided subsequently the modeling of surface wind fields over Antarctica, where katabatic winds are common (Falvey and Rojo 2016).…”

Cooling the Coldest Continent: The 4 December 2021 Total Solar Eclipse over Antarctica

“…Extremely dry air aloft enhances the radiative cooling of the snow-covered surface, resulting in an intense inversion layer at low levels (Handorf et al 1999;Cassano et al 2021). The stable, mostly clear, and exceptionally dry conditions over the interior of Antarctica have fueled the interest for performing astronomical observations despite obvious logistic challenges (Burton 2010;Falvey and Rojo 2016). The approximately parabolic shape of the Antarctic topography, with the highest elevations not far from its center, foster the development of strong katabatic winds draining cold air from the interior (Bromwich et al 1992;Heinemann et al 2019) and eventually converging with the circumpolar ring of the SH westerly winds around the Antarctic periphery (e.g., Marshall et al 2006).…”