Impact of model resolution and turbulence scheme on the representation of mountain waves and turbulence

IF 5.7 1区地球科学 Q1 ENVIRONMENTAL SCIENCES

Atmospheric Chemistry and Physics Pub Date : 2026-09-30 DOI:10.5194/acp-26-13721-2026

Roshny Siri Jagan,Juerg Schmidli

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引用次数: 0

Abstract

Simulating mountain waves and associated turbulence in the upper troposphere and lower stratosphere (UTLS) remains a challenge in numerical weather prediction (NWP). We investigate how the representation of mountain-wave dynamics and turbulence in the ICOsahedral Nonhydrostatic (ICON) model depends on model resolution and turbulence parameterization. ICON simulations were performed in NWP mode (ICON-NWP) with varying horizontal (2, 1 km, 500 m) and vertical (400, 200, 100 m) resolutions, using the operational turbulent kinetic energy scheme (ICON-TKE) and the newly developed two-energy turbulence scheme (ICON-2TE). The simulations were evaluated against high-frequency in situ observations from the Deep Propagating Gravity Wave Experiment (DEEPWAVE) over New Zealand on 12 July 2014, as well as a nested large-eddy simulation (ICON-LES) at 130 m resolution. The results show reasonable agreement with observations: ICON-LES more closely captures wavelength and phase, while ICON-NWP better reproduces wave amplitude. Near-convergence of the primary mountain wave and of turbulence structures requires horizontal grid spacings of 1 km or finer and vertical spacings in the UTLS of 200 m or finer, whereas trapped lee waves and downstream wave structure remain resolution-sensitive at these resolutions. Area-averaged, bulk measures allow this convergence behavior to be characterized more systematically: the low-level gravity-wave momentum flux continues to increase with increasing resolution from 1 km to 500 m. A key finding is that both turbulence schemes yield similar wave structures, despite large differences in simulated turbulent kinetic energy. This discrepancy is attributed to the empirical horizontal-shear source term of the operational TKE-scheme configuration, which produces spurious TKE at km-scale resolution. These results provide guidance on the resolution and turbulence representation needed for reliable simulations of small-scale mountain waves and turbulence in the UTLS.

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模式分辨率和湍流格式对山地波和湍流表示的影响

在数值天气预报（NWP）中，模拟对流层上层和平流层下层的山波和相关湍流（UTLS）仍然是一个挑战。我们研究了icoshedral Nonhydrostatic （ICON）模式中山波动力学和湍流的表征如何依赖于模式分辨率和湍流参数化。采用常规湍流动能格式（ICON- tke）和新开发的双能湍流格式（ICON- 2te），在不同水平（2、1 km、500 m）和垂直（400、200、100 m）分辨率的NWP模式（ICON-NWP）下进行了ICON模拟。这些模拟是根据2014年7月12日新西兰深度传播重力波实验（DEEPWAVE）的高频现场观测数据以及130米分辨率的嵌套大涡模拟（ICON-LES）进行评估的。结果表明，ICON-LES能较好地捕捉波长和相位，ICON-NWP能较好地再现波幅。初级山波和湍流结构的近辐合需要水平网格间距为1公里或更细，UTLS中的垂直网格间距为200米或更细，而被捕获的背风波和下游波结构在这些分辨率下仍然对分辨率敏感。面积平均的大量测量可以更系统地描述这种辐合行为：从1公里到500米，随着分辨率的增加，低空重力波动量通量继续增加。一个关键的发现是，两种湍流方案产生相似的波浪结构，尽管模拟的湍流动能有很大差异。这种差异归因于操作TKE方案配置的经验水平剪切源项，它在千米尺度分辨率下产生伪TKE。这些结果为在UTLS中可靠地模拟小尺度山波和湍流所需的分辨率和湍流表示提供了指导。

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来源期刊

Atmospheric Chemistry and Physics 地学-气象与大气科学

CiteScore

10.70

自引率

20.60%

发文量

702

审稿时长

6 months

期刊介绍： Atmospheric Chemistry and Physics (ACP) is a not-for-profit international scientific journal dedicated to the publication and public discussion of high-quality studies investigating the Earth''s atmosphere and the underlying chemical and physical processes. It covers the altitude range from the land and ocean surface up to the turbopause, including the troposphere, stratosphere, and mesosphere. The main subject areas comprise atmospheric modelling, field measurements, remote sensing, and laboratory studies of gases, aerosols, clouds and precipitation, isotopes, radiation, dynamics, biosphere interactions, and hydrosphere interactions. The journal scope is focused on studies with general implications for atmospheric science rather than investigations that are primarily of local or technical interest.