Estimation of the Variability of Mesoscale Energy Spectra with Three Years of COSMO-DE Analyses
Estimation of the Variability of Mesoscale Energy Spectra with Three Years of COSMO-DE Analyses
复制标题
通过三年的 COSMO-DE 分析估计中尺度能量谱的变化
DOI：
10.1175/jas-d-18-0155.1
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发表时间：
2019
影响因子：
3.1
通讯作者：
G. Craig
中科院分区：
文献类型：
--
作者：
T. Selz;L. Bierdel;G. Craig
在过去的几十年中，中尺度动能谱的研究主要集中在寻找一个动力机制，产生了一个普遍的谱斜率。在这里，我们调查光谱的变异性，使用3年的分辨率分析配置为德国（COSMO-DE）的COSMO。结果表明，中尺度动能谱是高度可变的时间，但发现在100公里左右的尺度上的可变性最小。高变率上发现的小尺度端的频谱（约10公里）是正相关的降水率对流是一个强大的方差源。另一方面，大尺度端（约1000公里）的变化与位涡相关，如预期的地转平衡流。相应地，小尺度下的降水与辐散动能的相关性更强，而大尺度下的位涡与旋转动能的相关性更强。所提出的研究结果表明，中尺度范围的光谱斜率和振幅是由这些大尺度和小尺度动力学过程的高档和低档影响的不断变化的组合，而不是由一个普遍的，本质上中尺度动力学机制。
Research on the mesoscale kinetic energy spectrum over the past few decades has focused on finding a dynamical mechanism that gives rise to a universal spectral slope. Here we investigate the variability of the spectrum using 3 years of kilometer-resolution analyses from COSMO configured for Germany (COSMO-DE). It is shown that the mesoscale kinetic energy spectrum is highly variable in time but that a minimum in variability is found on scales around 100 km. The high variability found on the small-scale end of the spectrum (around 10 km) is positively correlated with the precipitation rate where convection is a strong source of variance. On the other hand, variability on the large-scale end (around 1000 km) is correlated with the potential vorticity, as expected for geostrophically balanced flows. Accordingly, precipitation at small scales is more highly correlated with divergent kinetic energy, and potential vorticity at large scales is more highly correlated with rotational kinetic energy. The presented findings suggest that the spectral slope and amplitude on the mesoscale range are governed by an ever-changing combination of the upscale and downscale impacts of these large- and small-scale dynamical processes rather than by a universal, intrinsically mesoscale dynamical mechanism.