| Summary: | The Ridge and the Fen sites at Imnaviat creek are identical and support identical sensor suites. The heart of each system is an open-path eddy covariance system that measures the fluxes of carbon dioxide, water vapour and energy. In addition to this, each system measures standard meteorological and subsurface variables such as wind speed, air temperature and soil energy fluxes. The majority of these sensors were supplied by Campbell Scientific, Inc. The CSAT3 and the LI7500 form the core of the eddy covariance (EC) system and are used to measure high frequency fluctuations of the concentration of CO2, H2O and vertical wind speed in order to determine FCO2, Qe and Qh. Additionally, wind direction is determined by using the two horizontal measurements of wind speed from the CSAT3. The EC systems are positioned at heights of 3.18m and 2.20m at the Ridge and Fen sites respectively. The LI7500s are positioned 150 degrees behind each CSAT3 at a distance of 15cm and are oriented 30 degrees from vertical to reduce snow/ice/rain accumulation on the lenses. This results in an estimated measurement rejection angle of 30 degrees directly behind each EC system. At each station, the EC systems are oriented 150 degrees from true north into the dominant yearly wind direction in order to maximize the probability that measurements will be taken outside of the instrument rejection angle. Accordingly, the Renewable Energy Plants are located 30m away and in the centre of the measurement rejection zone. The other basic meteorological instruments such as the albedometer, the net radiometer, the PAR sensor, the Sonic Ranger, the tipping bucket rain gauge and the soil heat flux instruments are necessary to complete our measurements of the components of the energy balance in order to evaluate the performance of the EC system with an energy balance closure calculation and assist us with the quality control of the resultant dataset. Additionally, they assist in the evaluation of the impact of fundamental forcing factors on the observed mass and energy fluxes. Massman, W.J. [2000] A simple method for estimating frequency response corrections for eddy covariance systems, Agricultural and Forest Meteorology, 104, 185-198 Webb, E.K., G. I. Pearman, R. Leuning [1980] Correction of flux measurements for density effects due to heat and water vapour transfer, Quarterly Journal of the Royal Meteorological Society, 106, 85-100 Williams, M., L.E. Street, M.T. van Wijk, G.R. Shaver [2006] Identifying differences in carbon exchange among Arctic ecosystem types, Ecosystems, 9, 288-304
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