层积云覆盖的海洋边界层云详细微物理过程的数值模拟

文中建立了一个含显式分档的云微物理模式和辐射传输模式的一维 3阶湍流闭合模式 ,该模式可用于研究海洋边界层云中气溶胶和云的相互作用过程 ,同时提出了一种新的动力模式和微物理模式耦合方法 ,该方法可使动力模式中液态水相关项可以直接由微物理模式变量计算得到。作为模式的初步应用模拟了 2 0 0 1年APEX/ACE Asia在西太平洋上所观测到的一个个例。模拟结果和观测资料比较表明该模式基本上模拟出层积云覆盖的海洋边界层的基本结构

NUMERICAL STUDY ON CLOUD MICROPHYSICS OF STRATOCUMULUS-TOPPED MARINE BOUNDARY

Marine boundary layer stratus and stratocumulus clouds are of great importance f or the heat balance of the earth atmosphere system. Due to be highly variable i n time and space, direct measurement of clouds is never sufficiently dense to det ermine temporal and spatial variability in cloud depth, cloud droplet number, an d effective radius from the observations alone, nor can feedback mechanisms be e asily quantified solely on the basis of field data. Modeling of stratocumulus ha s received much attention in the past years.A one dimensional 3rd order turbulence closure model is developed to investiga te the aerosol cloud radiation turbulence interactions in the stratocumulus top ped marine boundary layer. The model has three coupled components: a size resolved microphysical model that resolves explicitly the size distributions of aerosols and cloud droplets, a detailed radiative model that calculates heating and cooli ng rate, and a one dimensional 3rd order turbulence closure model that calcula te s the dynamical and thermal_ dynamical processes. A new method is presented for coupling between dynamical model and microphysical model. This scheme allows the liquid water related correlations are directly calculated rather than parameter ized. On April 21, 2001 a marine stratocumulus was observed by the Caesar aircra ft over the west Pacific Rim south to Japan during 2001 APEX/ACE Asia field mea s urements. This was simulated as April 21, 2001 case by the model we presented he re. Model results have shown that the general features of the stratocumulus topped marine boundary layer predicted by the model are in agreement with the measurements. A new onboard CCN counter provides not only total CCN number concentration as the traditional CCN counters do at a certain supersaturation but also the CCN size d istribution information. The model results are consistent with both observations and expectations. Model results agree with the observed bulk thermodynamics and cloud properties. A one dimensional model with detailed cloud microphysics is a n attractive tool for studying the interactions between dynamics, cloud physics, and radiation processes during of the evolutions of stratocumulus clouds' micro structure.