HIGHLIGHTS OF COASTAL WAVES 1996

Some of the highlights of an experiment designed to study coastal atmo spheric phenomena along the California coast (Coastal Waves 1996 exper iment) are described. This study was designed to address several probl ems, including the cross-shore variability and turbulent structure of the marine boundary layer, the influence of the coast on the developme nt of the marine layer and clouds, the ageostrophy of the flow, the dy namics of trapped events, the parameterization of surface fluxes, and the supercriticality of the marine layer. Based in Monterey, Californi a, the National Center for Atmospheric Research (NCAR) C-130 Hercules and the University of North Carolina Piper Seneca obtained a comprehen sive set of measurements on the structure of the marine layer. The stu dy focused on the effects of prominent topographic features on the win d. Downstream of capes and points, narrow bands of high winds are freq uently encountered. The NCAR-designed Scanning Aerosol Backscatter Lid ar (SABL) provided a unique opportunity to connect changes in the dept h of the boundary layer with specific features in the dynamics of the flow field. An integral part of the experiment was the use of numerica l models as forecast and diagnostic tools. The Naval Research Laborato ry's Coupled Ocean Atmosphere Model System (COAMPS) provided high-reso lution forecasts of the wind field in the vicinity of capes and points , which aided the deployment of the aircraft. Subsequently, this model and the MIUU (University of Uppsala) numerical model were used to sup port the analysis of the field data. These are some of the most compre hensive measurements of the topographically forced marine layer that h ave been collected. SABL proved to be an exceptionally useful tool to resolve the small-scale structure of the boundary layer and, combined with in situ turbulence measurements, provides new insight into the st ructure of the marine atmosphere. Measurements were made sufficiently far offshore to distinguish between the coastal and open ocean effects . COAMPS proved to be an excellent forecast tool and both it and the M IUU model are integral parts of the ongoing analysis. The results high light the large spatial variability that occurs directly in response t o topographic effects. Routine measurements are insufficient to resolv e this variability. Numerical weather prediction model boundary condit ions cannot properly define the forecast system and often underestimat e the wind speed and surface wave conditions in the nearshore region. This study was a collaborative effort between the National Science Fou ndation, the Office of Naval Research, the Naval Research Laboratory, and the National Oceanographic and Atmospheric Administration.