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Ivotuk ATLAS field site north slope Alaska

University of Alaska Fairbanks

Artic Transitions in the Land Atmosphere System (ATLAS)

IVOTUK

North slope field site

This study addresses the spatial variability in land-atmosphere exchange, especially along climate gradients, and gathers information to assess potential temporal changes in these fluxes in response to climatic change. During 1998-99, the main emphasis has been on initiating field studies and developing an integrated approach to study of land-atmosphere interactions. The field work was focused at Ivotuk and anchored the southern end of the ATLAS North Slope transect. In 1999-2000, the field work will shift to the Seward Peninsula.

Land-atmosphere measurements at Ivotuk

Field work at Ivotuk included measurements of energy and moisture exchange, vegetation biomass and structure, soil thermal characteristics in relation to the permafrost layer and parameters important in catchment-scale hydrological processes. Energy fluxes were measured at one static summer site located over typical Moist Acidic Tussock tundra (MAT) and a mobile tower has been used to characterize three other ecosystem types (Shrub tundra (SHRUB), Moist Non-Acidic (MNT) tundra, and a Sphagnum dominated tundra (MOSS)). At each tower site an eddy correlation system was established to measure the latent, sensible, and carbon dioxide fluxes. On an adjacent tower at each site a climate station measured soil heat fluxes, soil moisture, soil temperature, net radiation, incoming solar radiation, photosynthetic photon flux density, barometric pressure, air temperature at two levels, relative humidity at two levels and wind speed at two levels. At the static site a full radiation balance was measured and this equipment was shifted between sites during the season to quantify the radiative exchanges over each ecosystem type.

In conjunction with the energy exchange and permafrost measurements, the vegetation characteristics within the flux tower footprint were documented thoroughly. Characteristics that were measured include; percentage abundance by species (with emphasis on moss characteristics), leaf area index, NDVI, and canopy height. Above ground biomass harvests were conducted during peak biomass at each site to document net primary productivity (NPP), carbon and nitrogen content, and plant resource allocation by functional type. In association with the above ground biomass harvests, root cores were taken to examine the allocation of plant resources to below ground biomass and water and nutrient uptake.

In addition, soil temperature profiles and soil moisture measurements at all sites were established during mid-summer to characterize permafrost dynamics over successive seasons. These measurements will address how major arctic ecosystem types differ in their surface energy exchange and permafrost dynamics and how this will likely affect the physical soil environment (i.e. thermokarst development) and climate feedbacks on different time scales.