| The current study uses Local Analysis and Prediction System (LAPS) cloud analyses at a 3.3 km resolution to study marine stratus (MS) dynamics over San Francisco International Airport (SFO). A thick MS layer caused a late clearing over SFO due to trough induced lifting and adiabatic cooling. LAPS incorporated surface and upper air data, used ETA forecasts as first guess fields, and evaluated its cloud fields against visible satellite images. Four LAPS output parameters served as cloud proxies: LWC, FCC, and unbalanced and balanced RH. Grid points with proxy values above the specified thresholds were defined as "cloudy."; ETA analyses in conjunction with the LAPS default threshold values were too dry to produce cloud fields. Lower thresholds produced good agreement with satellite observations for all parameters except LWC, which depends strongly on initial RH values. Further studies should address effects on LAPS analysis fields from first guess fields, terrain resolution, and observational data density. |
