First Assessment of Mountains on Northwestern Ellesmere Island, Nunavut, as Potential Astronomical Observing Sites

Abstract

Ellesmere Island, at the most northerly tip of Canada, possesses the highest mountain peaks within 10 degrees of the pole. The highest is 2616 m, with many summits over 1000 m, high enough to place them above a stable low-elevation thermal inversion that persists through winter darkness. Our group has studied four mountains along the northwestern coast which have the additional benefit of smooth onshore airflow from the ice-locked Arctic Ocean. We deployed small robotic site testing stations at three sites, the highest of which is over 1600 m and within 8 degrees of the pole. Basic weather and sky clarity data for over three years beginning in 2006 are presented here, and compared with available nearby sea-level data and one manned mid-elevation site. Our results point to coastal mountain sites experiencing good weather: low median wind speed, high clear-sky fraction and the expectation of excellent seeing. Some practical aspects of access to these remote locations and operation and maintenance of equipment there are also discussed.

The SCAR Astronomy & Astrophysics from Antarctica Scientific Research Programme

“…• Remote Ellesmere Island mountain sites are accessible by helicopter in summer and above the thermal inversion in winter, providing reliable logistics and good weather (Steinbring et al 2010). Skies are clear 65% of the time or better, as expected from satellite measurements.…”

“…The analogy to the Greenland icecap initiated observations at Summit (Andersen & Rasmussen 2006, Andersen, Pedersen & Sorensen 2010. An independent investigation into the feasibility of observations from high and very remote mountain peaks on northwestern Ellesmere Island was also undertaken (Steinbring et al 2008, Wallace et al 2008, anticipating the avoidance of boundary conditions associated with the surface of an ice plateau (Hickson et al 2010, Steinbring et al 2010. A strong advantage for a high mountain site over the icecap has not yet been proved, and in the meantime a compromise afforded by the year-round logistics provided by the mid-elevation site at PEARL is also being investigated.…”

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

“…A potential field campaign would ideally include, apart from standard meteorological sensors, instruments to measure cloud cover, turbulence and seeing. The experiences described in Steinbring et al (2010) in the Canadian Arctic provide an interesting example as to how such a field campaign could be carried out. Given that there exist doubts as to the viability of the sites, the most prudent course of action may be to collaborate with other groups also interested in obtaining meteorological observations in the area (glaciologists, geodesists and climatologists being obvious candidates).…”

Thermal Infrared Sky Background for a High-Arctic Mountain Observatory

“…Transparency Range and Applicability Only the thermal component of emission in K-band and redder is of interest here. Transparency of the atmosphere in this regime is due primarily to water vapour content, and Eureka is extremely dry, with a mean precipitable water vapour (PWV) in winter of 2 mm (Lesins 2009), and best conditions approaching 1 mm at PEARL (Steinbring et al 2010). Zodiacal continuum emission makes a relatively small addition to the background near 2.3 µm, and a clean cutoff here avoids a plethora of narrow hydroxyl lines blueward.…”