【摘 要】
：
日间对流边界层最显著的结构特征是在热力作用下所形成的组织化对流.与小尺度湍涡不同的是,组织化对流具有边界层尺度的垂直相干性,可实现垂直贯穿边界层的非局地物质和能量传输.本文针对对流边界层中的动量混合,探究组织化对流对动量输送的贡献.以高精度大涡模拟数据为研究资料,通过傅里叶变换、本征正交分解和经验模态分解3种滤波方法,分离组织化对流和背景湍涡,计算与两者相关的非局地和局地动量通量,发现与组织化对流相关的非局地动量通量是总通量的重要组成部分,并主导混合层中的垂直动量输送.而后,基于协谱和相位谱分析,探究组织
【机 构】
：
中尺度灾害性天气教育部重点实验室,南京210023;南京大学大气科学学院,南京210023
论文部分内容阅读
日间对流边界层最显著的结构特征是在热力作用下所形成的组织化对流.与小尺度湍涡不同的是,组织化对流具有边界层尺度的垂直相干性,可实现垂直贯穿边界层的非局地物质和能量传输.本文针对对流边界层中的动量混合,探究组织化对流对动量输送的贡献.以高精度大涡模拟数据为研究资料,通过傅里叶变换、本征正交分解和经验模态分解3种滤波方法,分离组织化对流和背景湍涡,计算与两者相关的非局地和局地动量通量,发现与组织化对流相关的非局地动量通量是总通量的重要组成部分,并主导混合层中的垂直动量输送.而后,基于协谱和相位谱分析,探究组织化对流的空间结构对动量传输的影响,发现在热力主导的不稳定环境中,单体型环流结构对动量的传输效率较低.而在风切较强的近中性环境中,滚涡型组织化结构可使垂直和水平流向扰动速度的相位差减小,从而提升动量传输效率.研究结果表明,边界层方案需要包含非局地动量通量项,其参数化应考虑整体稳定度对传输效率的影响.
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