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

• Published in: Climate Dynamics
• Main Authors: Grachev, A. A., Persson, O. G., Uttal, T., Akish, E. A., Cox, C. J., Morris, S. M., Fairall, C. W., Stone, R. S., Lesins, G., Makshtas, A. P., Repina, I. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2018
• Subjects: Arctic; Arctic Ocean; Canada; Eureka; Nunavut; Tiksi; permafrost; polar night; Siberia
• Online Access: https://oceanrep.geomar.de/id/eprint/43052/; https://oceanrep.geomar.de/id/eprint/43052/1/Grachev.pdf; https://doi.org/10.1007/s00382-017-3983-4

This observational study compares seasonal variations of surface fluxes (turbulent, radiative, and soil heat) and other ancillary atmospheric/surface/permafrost data based on in-situ measurements made at terrestrial research observatories located near the coast of the Arctic Ocean. Hourly-averaged multiyear data sets collected at Eureka (Nunavut, Canada) and Tiksi (East Siberia, Russia) are analyzed in more detail to elucidate similarities and differences in the seasonal cycles at these two Arctic stations, which are situated at significantly different latitudes (80.0°N and 71.6°N, respectively). While significant gross similarities exist in the annual cycles of various meteorological parameters and fluxes, the differences in latitude, local topography, cloud cover, snowfall, and soil characteristics produce noticeable differences in fluxes and in the structures of the atmospheric boundary layer and upper soil temperature profiles. An important factor is that even though higher latitude sites (in this case Eureka) generally receive less annual incoming solar radiation but more total daily incoming solar radiation throughout the summer months than lower latitude sites (in this case Tiksi). This leads to a counter-intuitive state where the average active layer (or thaw line) is deeper and the topsoil temperature in midsummer are higher in Eureka which is located almost 10° north of Tiksi. The study further highlights the differences in the seasonal and latitudinal variations of the incoming shortwave and net radiation as well as the moderating cloudiness effects that lead to temporal and spatial differences in the structure of the atmospheric boundary layer and the uppermost ground layer. Specifically the warm season (Arctic summer) is shorter and mid-summer amplitude of the surface fluxes near solar noon is generally less in Eureka than in Tiksi. During the dark Polar night and cold seasons (Arctic winter) when the ground is covered with snow and air temperatures are sufficiently below freezing, the near-surface ...