225 GHz Atmospheric Opacity Measurements from Two Arctic Sites

TL;DR

This study measures 225 GHz atmospheric opacity at two Arctic sites to evaluate their suitability for submillimeter and THz astronomy, finding Summit Station particularly promising due to its low opacity levels.

Contribution

It provides the first comprehensive comparison of atmospheric transparency at Arctic sites for submillimeter astronomy, highlighting Summit Station's exceptional conditions.

Findings

Summit Station has opacity levels comparable to ALMA in Chile.

Winter opacity at Summit Station is similar to the South Pole.

Both sites show high atmospheric transparency for submillimeter observations.

Abstract

We report the latest results of 225 GHz atmospheric opacity measurements from two arctic sites; one on high coastal terrain near the Eureka weather station, on Ellesmere Island, Canada, and the other at the Summit Station near the peak of the Greenland icecap. This is a campaign to search for a site to deploy a new telescope for submillimeter Very Long Baseline Interferometry and THz astronomy in the northern hemisphere. Since 2011, we have obtained 3 months of winter data near Eureka, and about one year of data at the Summit Station. The results indicate that these sites offer a highly transparent atmosphere for observations in submillimeter wavelengths. The Summit Station is particularly excellent, and its zenith opacity at 225 GHz is statistically similar to the Atacama Large Milllimeter/submillimeter Array in Chile. In winter, the opacity at the Summit Station is even comparable to that observed at the South Pole.