对流边界层灰区尺度数值模拟研究进展

Research Progress on the Numerical Simulation at Gray-zone Scales of the Convective Boundary Layer

随着计算能力的不断提高,数值天气预报模式的水平网格分辨率已经达到公里—次公里量级,这一网格尺度与对流边界层中的湍流特征尺度相当,数值模式可以对有组织对流结构进行解析计算。传统的一维边界层参数化方案(适用于几公里或更粗水平分辨率)和大涡模拟三维湍流闭合方案(适用于几十米以下水平分辨率)的假设条件在这一尺度上均不成立,称为对流边界层的灰区尺度。在讨论传统参数化方法的适用性和局限性的基础上,从理论、方案方法和影响3个方面介绍了对流边界层灰区尺度的研究进展,总结了近20年来国内外发展的各对流边界层灰区尺度模拟方法的特点,探讨了该尺度上边界层过程对数值模式中其他物理过程(如浅/深对流等)的影响,最后展望了未来可能的研究方向和思路。

As computing power continues to improve,the horizontal grid resolution of numerical weather prediction models has reached the kilometer-to-sub-kilometer scale.This grid scale is comparable to the characteristic turbulent scales in the convective boundary layer,allowing the numerical models to resolve the organized convective structures.The assumptions of traditional one-dimensional boundary layer parameterization schemes(suitable for horizontal resolutions of several kilometers or coarser)and large eddy simulation threedimensional turbulent closure schemes(suitable for horizontal resolutions below several tens of meters)do not hold at this scale,which is referred to as the gray zone.This study discusses the applicability and limitations of traditional parameterization methods and introduces the gray zone of the convective boundary layer from three perspectives:theory,methodological approaches,and impact.It summarizes the characteristics of the simulation methods at the CBL gray zone scale developed over the past two decades and explores the impact of the boundary layer process simulation at this scale on other physical processes(e.g.,shallow/deep convection)in numerical models.Further,we anticipate future research directions and approaches.