After the site reconnaissance in Wrigley, Karoline and Manuel spent a week at the Scotty Creek watershed to ensure a sufficient power supply for the two tower setups over the winter and take down sensitive equipment, which cannot withstand the harsh winter conditions typical at this latitude. The beginning of the trip was delayed by a day because the freezing drizzle prevented the helicopter from taking off. Once they arrived at the field site, they found the entire forest covered in small ice crystals.
Also our sensors were covered in ice, which was easily detectable by the low quality of the data. Luckily, Karoline and Manuel could quickly clean the sensors to continue with high quality measurements. Another task was the enhancement of the power supply system. The short daylight period between November and February requires a high capacity of solar panels and batteries to ensure continuous high frequency measurements of meteorological variables. Our first experiences during the winter 2013/14 have revealed weak points in the power supply system that needed to be fixed.
Karoline and Manuel also prepared the setup for an eddy covariance sensor intercomparison campaign at the 15 m tower on the peat plateau that will take place in spring 2015. Compared to most mid-latitude ecosystems, spring and winter CO2 fluxes at Scotty Creek are relatively small and the reduction of measurement uncertainties and biases due to sensor performance is a necessary prerequisite for meaningful ecological interpretations of these data.
Some sites could not be visited because the lakes at the field site were not safe to cross by foot. The lakes were covered with a thin ice layer but open water patches were still visible. On some days, Karoline and Manuel could hear the ice “working”. Apparently, tensions in the ice produced undefinable sounds that could be heard over several hundred meters. The snow covered landscape looked like in late winter but below the snow standing water and saturated peat reminded us that the freeze up was just about to take place.
Photo (above): Shoreline of Goose Lake (Karoline Wischnewski)
Eddy Covariance Instruments with some “frosting” (Photo: Manuel Helbig)