Long-term Monitoring of Sensible and Latent Heat Fluxes Using Eddy Covariance at a High-Arctic Permafrost Site on Svalbard, Norway

Land-atmosphere interactions are an important element in the energy and water budget in permafrost regions. We present long-term measurements of sensible and latent heat fluxes at a high-arctic continuous permafrost site on Svalbard, Norway, using the eddy covariance method. The site is situated in hilly tundra at the foot of two major glaciers, and is characterized by sparse vegetation alternating with exposed soil and rock fields. The study was performed from April to September in the years 2007 and 2008, thus covering a period from late winter until the end of the summer season in both years.\\The general pattern of the measured fluxes was largely similar in 2007 and 2008. During April, temperatures ranged from $-20\deg$C to $+5\deg$C, with an average of $-11\deg$C both in 2007 and 2008. Sensible heat fluxes were mostly negative, corresponding to an energy transfer from the atmosphere to the snow pack. The latent heat flux was generally positive, but remained low most of the time. With a temperature remaining rather constant between $-5\deg$C and $+5\deg$C and predominantly neutral atmospheric exchange conditions during most of May and June, both measured fluxes were comparatively insignificant. The appearance of large snow free patches around the end of June triggered a strong increase of sensible and latent heat fluxes. Hereby, the latent heat flux was approx. twice as large as the sensible heat flux, most likely due to very wet soil conditions directly after snow melt. This situation reversed during July, when the tundra increasingly dried up in most of the potential fetch area of the eddy system. The immediate surrounding of the measurement site could then be characterized as moderately moist tundra. Both sensible and latent heat fluxes remained largely positive, and displayed a strong diurnal course, with peak fluxes associated with maxima of solar radiation.\\In relation with recordings of the radiative parts of the energy budget, eddy covariance measurements have proven to be a valuable method to capture a more complete picture of energy fluxes at this maritime permafrost site