An Observational Case Study of Mesoscale Convection Over Lake Michigan on 10 January 1984 PDF Download

Author: Steven R. Gilbert
Publisher:
ISBN:
Category : Convection (Meteorology)
Languages : en
Pages : 210

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Book Description
Surface, upper air, and aerological data from the Lake-Effect Snow Studies (LESS) field program conducted 1 Dec - 28 Jan 1984 were examined to study the modification of continental polar air masses heated from below by the large, comparatively warm Great Lakes. This study focused on one particular cold air outbreak that occurred as a northerly flow event over Lake Michigan 10 Jan 1984. Spatial cross-sections and streamline analyses show the combined effects of air mass modification by the Great Lakes. The total depth of the boundary layer at the southern and of Lake Michigan was uncharacteristically high, over 2.4 km, due to the air first being modified by Lake Superior, and then by the full fetch of Lake Michigan. Aircraft data sets of ambient air temperature, virtual potential temperature, specific humidity, liquid water content, and the u, v, and w wind components sampled at a rate of 20/s were analyzed to determine the structure and interaction of the convectively mixed layer with the capping inversion layer. An important finding is the identification of a penetrative convection layer that resides between the top of the fully-mixed layer and the bottom of the inversion layer. Evidence from the aircraft data analysis shows the characteristics of this layer and the associated fluxes and entrainment. Penetrative convection into the traditional capping inversion is identified as convective turbulent eddies that continually mix with the stable air and thus lose their identity.