Variability of Stratocumulus and its Boundary Layer Measured During UPPEF2012

During September 2012, extensive aircraft measurements were made off the coast of Monterey, CA as part of the ONR sponsored Departmental Research Initiative (DRI), the Unified Physical Parameterization for Extended Forecast (UPPEF). UPPEF 2012 field measurement utilized the Twin Otter research aircraft operated by the NPS Center for Interdisciplinary Remote Piloted Aircraft Study (CIRPAS) for 12 research flights, 10 of which were made in cloudy boundary layers with various cloud fractions. The goal of the experiment was to study the cloud structure, turbulence, and other related physical processes in broken stratocumulus using in situ instruments onboard the aircraft. We will present the overall measurement strategy and clouds/boundary layer conditions sampled during UPPEF2012 and highlights of special characteristics of the cloud topped boundary layers. In particular, we will examine the characteristics of the cool downdrafts in the cloud layer observed from several flights to identify the role of entrainment in the scale selection of the cloud and cloud breaks. The probability distribution of key cloud variables will be shown and will be compared with results from previous measurements in different geographical locations.