Where is Ridge A?

Abstract

First identied in 2009 as the site with the lowest precipitable water and best terahertz transmission on Earth, Ridge A is located approximately 150 km south of Dome A, Antarctica. To further rene this optimum location prior to deployment in 2012 of a robotic THz observatory, we have modelled the atmospheric transmission as a function of location over a 1,000,000 km square grid using three years of data from the Microwave Humidity Sounder on the NOAA-18 satellite. The modelling identies a broad area of exceptionally low water vapour close to the 4,000 metre elevation contour, reaching below 100 microns for extended periods of time.