Seasonal and latitudinal variations of surface fluxes at two Arctic terrestrial sites

摘要: This observational study compares seasonal variations of surface fluxes (turbulent, radiative, and soil heat) other ancillary atmospheric/surface/permafrost data based on in-situ measurements made at terrestrial research observatories located near the coast Arctic Ocean. Hourly-averaged multiyear sets collected Eureka (Nunavut, Canada) Tiksi (East Siberia, Russia) are analyzed in more detail to elucidate similarities differences cycles these two stations, which situated significantly different latitudes (80.0°N 71.6°N, respectively). While significant gross exist annual various meteorological parameters fluxes, latitude, local topography, cloud cover, snowfall, characteristics produce noticeable structures atmospheric boundary layer upper temperature profiles. An important factor is that even though higher latitude sites (in this case Eureka) generally receive less incoming solar radiation but total daily throughout summer months than lower Tiksi). leads a counter-intuitive state where average active (or thaw line) deeper topsoil midsummer almost 10° north Tiksi. The further highlights latitudinal shortwave net as well moderating cloudiness effects lead temporal spatial structure uppermost ground layer. Specifically warm season (Arctic summer) shorter mid-summer amplitude noon During dark Polar night cold seasons winter) when covered with snow air temperatures sufficiently below freezing, near-surface environment stably stratified hourly averaged turbulent quite small irregular downward sensible heat upward latent carbon dioxide fluxes. magnitude increases rapidly disappears rise above freezing during spring melt eventually reaches maximum. Throughout strong (uptake by surface) typically observed indicating persistent unstable (convective) stratification. Due combined day length zenith angle, convective forms High (e.g., can reach long-lived quasi-stationary states summer. late early autumn all decrease decreases falls freezing. Unlike Eureka, pronounced zero-curtain effect consisting sustained hiatus point fall due wetter and/or water saturated soils.