Tests of Large-Eddy Simulations of the Stratocumulus Topped Planetary Boundary Layer

这笔拨款支持了DYCOMS-II（海洋层积云动力学和化学），这是2001年7月在加利福尼亚海岸进行的一项野外合作项目。工作内容包括：(1)基于NCAR C-130夜间7次飞行对海洋层积云的观测研究，该飞行装备用于测量边界层内和边界层间的通量；(2)对这些数据和以往的海洋云顶边界层数据进行分析；(3)与大涡模拟（LES）结果的比较。这些实验是专门设计来提供验证LES所需的数据的。特别感兴趣的量是夹带率、云界面特性的结构特征和湍流空气运动的统计特性。证明模拟这些量的能力是建立LES作为生成综合数据的工具的关键一步，从而能够在大尺度大气模式中检验假设和构建参数化。

This grant supports DYCOMS-II (Dynamics and Chemistry of Marine Stratocumulus), a collaborative field program conducted off the coast of California in July 2001. The work consists of (1) an observational study of marine stratocumulus clouds based on seven nocturnal flights of the NCAR C-130 equipped for measuring fluxes in and across the boundary layer; (2) analysis of these and previous data on the cloud-topped marine boundary layer; (3) comparison of the observations with the results of large-eddy simulations (LES). The experiments are designed specifically to provide the data needed to validate LES. Quantities of special interest are entrainment rates, structural features of cloud interfacial properties, and statistical properties of the turbulent air motions. Demonstrating the ability to simulate these quantities is a crucial step in establishing LES as a tool for generating synthetic data to enable the testing of hypotheses and the construction of parameterizations to be used in large-scale atmospheric models.