The East Trout Lake observatory is located close to the southern edge of a boreal forest region in central Saskatchewan at 54°21'N, 104°59'W and at an elevation of 492m above sea level. The observatory is situated in a small clearing of approximately 1 km2. 4 levels or meteorology and intake lines (95, 55, 33, 22m) are installed on a 105m SaskTel communication tower. Continuous measurements of CO2, CH4, CO, N2O and SF6 begun in September 2005 to compliment the ongoing CO2 and water flux measurements at number of flux sites in this region. The program also includes weekly flask-sampling for CO2, CH4, CO, N2O, H2, SF6, 13C and 18O in CO2 as well as and weekly aircraft vertical profile sampling by NOAA for the same trace species as part of the North American Carbon Program (NACP). Aerosol optical and chemical measurements are in operation since May 2006. The terrain in the surrounding area is slightly rolling with vegetation primarily consisting of black spruce but the forest also consists of deciduous-type larch and trembling aspen.