Impacts of land cover variability on scalar similarity and efficiency of scalar transport

Turbulent eddies are a prime transport mechanism for scalars in the surface layer. It has been well-established that different land cover types will alter the turbulent dynamics and potentially, the validity of Monin-Obukhov similarity theory (MOST), but less is known about how climatological forcings affect the impacts of land cover. Therefore, the objective is to investigate variations in precipitation, soil moisture, and vegetation phenology on scalar similarity and relative efficiency of water and carbon transport. We analyzed two years of high-frequency (20 Hz) velocity and scalar concentration data from three climatologically similar micrometeorological stations in Northeastern Kansas. One station is located at the Nelson Environmental Study Area north of Lawrence, KS is composed of mixed C3/C4 grasses, and two stations are located at Konza Prairie 14 km south of Manhattan, KS—one being upland with relatively homogeneous C4 grass and the other being burned every four years and experiencing woody encroachment. The applicability of MOST, variability in the turbulent dynamics associated with substantial surface forcings across a range of time scales and the efficiency of carbon and water transport by the surface-layer eddies are determined for all three stations. We expect that the most homogeneous surfaces will have the highest agreement with MOST, especially during the post-senescent months. We also speculate that a strong surface flux of carbon and/or water vapor and strong precipitation events will alter the transport relative efficiency of these scalars. These findings are relevant regarding the contribution of small-scale processes to widely-spanning climates.