A comparative approach to regional variation in surface fluxes using mobile eddy correlation towers

We describe a comparative approach to micrometeorological measurements of surface energy, water vapor, and trace gas fluxes, in which mobile eddy correlation towers are moved among sites every 9-14 days, allowing both direct and indirect comparison of fluxes among ecosystem types. Structurally distinct ecosystems in Alaskan arctic tundra differed in the relationships between net radiation and surface energy fluxes, whereas structurally similar ecosystems showed constant relationships, even when they experienced quite different climate. An intercomparison of two towers simultaneously operated at the same location provided a reference for the systematic error of such comparisons. We suggest general criteria for comparing flux measurements made in different ecosystems.