Constructing vertical profiles of kinematic turbulent fluxes during OWLeS field campaign

Constructing vertical profiles of kinematic turbulent fluxes during OWLeS field campaign

Timothy W. See, James T. Simkins, Todd D. Sikora, Richard D. Clark

Lake-effect snow events remain a major weather hazard for residents and commerce surrounding the Great Lakes. While the greatest snow accumulations are found within a few kilometers of the downwind lakeshore, these snow systems can persist far downstream from of the parent lakes. One of the objectives of the Ontario Winter Lake-effect Systems (OWLeS) project is to examine the boundary layer processes during episodes of downwind persistence. Using a combination of surface flux measurements, one Hz time series of conventional meteorological variables from a tethered balloon system, and airborne flux measurements from the University of Wyoming King Air, we are able to construct a vertical profile of kinematic heat and momentum flux from the surface to the aircraft flight level. The surface and aircraft fluxes are calculated directly using eddy-covariance methods. To fill in the gap between the surface and the aircraft, tethersondes deployed at three different heights along a tether line provide the measurements from which fluxes can be derived from the vertical gradients of temperature, absolute humidity, and component wind speed. The results of this analysis are presented here for six IOPs during which lake-effect snow events occurred.