Coastal orography can impose distinct imprints on the structure and dynamic behavior of the marine atmospheric boundary layer (MABL). Abrupt changes in MABL depth, flow speed, and gradients across the MABL top arising from the interaction of supercritical winds with varying coastal orography have been the subject of several recent investigations. Here use is made of the NRL COAMPS model and the ONR sponsored COAST data set to investigate the nature of expansion fans, hydraulic jumps, and other supercritical MABL flow features observed along the California coast. We explore the impact of these abrupt MABL variations, which are particularly associated with points and capes,upon the wind, temperature, and moisture fields. Several examples of the dramatic consequences that can occur due to such supercritical flow interactions will be presented. For example, a case study of unique, trapped coastal wave clouds upwind of coastal orography will be presented. Also, we consider a case in which an elevated trapping layer for electromagnetic waves (e.g., radars) is forced to ascend and weaken on the upwind (north) side of Cape Mendocino due to the strong orographic blocking of supercritical flow in the MABL. In the lee of the Cape, the trapping layer descends sharply to a near surface-based duct as the boundary layer rapidly shallows and the flow accelerates. The role of MABL clouds in altering MABL structure and refractive conditions will be explored as
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