Boundary layer and mesoscale structure over Lake Michigan during a wintertime cold air outbreak

Abstract

Mean east-west cross sections for this northerly flow event have been prepared for heat, moisture, and momentum fields along with spectral decomposition and turbulent flux statistics. Results have been interpreted on the basis of three generalized spatial domains: mesoscale≥5 km, large eddies from 100 m to <5 km, and higher frequency turbulence <100 m. Mesoscale structures identified in the mean cross-sections include the lower Michigan land breeze, a strong offshore convergence snow band, cloud streets and precipitation bands over the lake, and entrainment spikes in the vicinity of the inversion layer. Analyses of particle concentrations, sizes and liquid water content have also been presented in mean cross sections, which correspond well with all identifiable mesoscale structures. This study has also examined a "hand-picked' data set in the mixed layer over the middle of the lake not affected by the land breeze and inversion layer phenomena. -from Authors