Development and Testing of a Simple Microphysical-ConvectiveRadiative Model of Marine Boundary-Layer Clouds

鉴于其巨大的潜在气候影响，云凝结核(CCN)在决定云的全球分布及其光学性质方面的作用目前引起了极大的兴趣，但尚未得到很好的了解。对海洋边界层中可获得的稳定状态的本质的洞察将通过使用一个简单的模型来模拟气溶胶、云和辐射之间的相互作用来获得，该模型以参数化的方式描述了系统的关键组件。待开发、实施和测试的边界层云模式包括：(1)基于物理的CCN源、汇、和运输；(2)边界层云的形成和消散的参数化，包括预报的CCN所规定的细雨形成的影响；以及(3)云边界层中辐射传输的参数化，包括太阳辐射和地面辐射，并考虑了云粒数密度和粒度分布以及云中液态水的含量。1992年大西洋平流层积云转换实验(ASTEX)的一个案例研究将被选中并用于检验该模型。这项拟议的研究将为未来将CCN物理纳入大气环流模式的工作奠定基础。

In view of their large potential climate impacts, the role of cloud condensation nuclei (CCN) in determining the global distribution of clouds and their optical properties is of great current interest, but is not yet well understood. Insight into the nature of the steady states attainable in the marine boundary layer will be obtained by simulating the interactions between aerosols, clouds, and radiation using a simple model that describes the key components of the system in a parameterized way. The boundary- layer cloud model to be developed, implemented, and tested includes: (1) A physically based parameterization of CCN sources, sinks, and transports; (2) A parameterization of boundary-layer cloud formation and dissipation, including the effects of drizzle formation as regulated by the predicted CCN; and (3) A parameterization of radiative transfer in the cloudy boundary layer, including both solar and terrestrial radiation, and taking into account the cloud particle number density and size distribution and the cloud liquid water content. A case study from the 1992 Atlantic Stratocumulus Transition Experiment (ASTEX) will be selected and used to test the model. The proposed study will provide a foundation for future work to incorporate CCN physics into general circulation models.