A Multimoment Bulk Microphysics Parameterization. Part II: A Proposed Three-Moment Closure and Scheme Description
A Multimoment Bulk Microphysics Parameterization. Part II: A Proposed Three-Moment Closure and Scheme Description
复制标题
DOI：
10.1175/jas3535.1
复制
发表时间：
2005-09
影响因子：
3.1
通讯作者：
J. Milbrandt;M. Yau
中科院分区：
文献类型：
--
作者：
J. Milbrandt;M. Yau
摘要 许多二矩整体方案使用 N(D) = N0Dαe−λD 形式的三参数伽玛分布来描述给定水凝物类别的尺寸谱。这些方案预测质量含量和总数浓度的变化，从而允许 N0 和 λ 作为预后参数变化，同时固定形状参数 α。正如本研究第一部分所示，代表水凝物尺寸谱相对分散度的形状参数在体微物理方案中的沉降和瞬时增长率计算中起着重要作用。通过允许 α 作为预测矩的诊断函数而不是使用固定值方法而变化，显示出显着的改进。然而，理想情况下，α 应该是一个独立的预后参数。在本文中，开发了一种闭合公式来计算尺寸分布的三阶矩（雷达反射率）的源项和汇项。通过质量 c 的预测方程...
Abstract Many two-moment bulk schemes use a three-parameter gamma distribution of the form N(D) = N0Dαe−λD to describe the size spectrum of a given hydrometeor category. These schemes predict changes to the mass content and the total number concentration thereby allowing N0 and λ to vary as prognostic parameters while fixing the shape parameter, α. As was shown in Part I of this study, the shape parameter, which represents the relative dispersion of the hydrometeor size spectrum, plays an important role in the computation of sedimentation and instantaneous growth rates in bulk microphysics schemes. Significant improvement was shown by allowing α to vary as a diagnostic function of the predicted moments rather than using a fixed-value approach. Ideally, however, α should be an independent prognostic parameter. In this paper, a closure formulation is developed for calculating the source and sink terms of a third moment of the size distribution—the radar reflectivity. With predictive equations for the mass c...