气候变化领域集成服务门户(CCPortal): Lagrangian gravity wave spectra in the lower stratosphere of current (re)analyses

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DOI	10.5194/acp-20-9331-2020
	Lagrangian gravity wave spectra in the lower stratosphere of current (re)analyses
	Podglajen A.; Hertzog A.; Plougonven R.; Legras B.
发表日期	2020
ISSN	1680-7316
起始页码	9331
结束页码	9350
卷号	20 期号:15
英文摘要	Due to their increasing spatial resolution, numerical weather prediction (NWP) models and the associated analyses resolve a growing fraction of the gravity wave (GW) spectrum. However, it is unclear how well this "resolved"part of the spectrum truly compares to the actual atmospheric variability. In particular, the Lagrangian variability, relevant, for example, to atmospheric dispersion and to microphysical modeling in the upper troposphere-lower stratosphere (UTLS), has not yet been documented in recent products. To address this shortcoming, this paper presents an assessment of the GW spectrum as a function of the intrinsic (air parcel following) frequency in recent (re)analyses (ERA-Interim, ERA5, the ECMWF operational analysis and MERRA-2). Long-duration, quasi-Lagrangian balloon observations in the equatorial and Antarctic lower stratosphere are used as a reference for the atmospheric spectrum and are compared to synthetic balloon observations along trajectories calculated using the wind and temperature fields of the reanalyses. Overall, the reanalyses represent realistic features of the spectrum, notably the spectral gap between planetary and gravity waves and a peak in horizontal kinetic energy associated with inertial waves near the Coriolis frequency f in the polar region. In the tropics, they represent the slope of the spectrum at low frequency. However, the variability is generally underestimated even in the low-frequency portion of the spectrum. In particular, the near-inertial peak, although present in the reanalyses, has a reduced magnitude compared to balloon observations. We compare the observed and modeled variabilities of temperature, zonal momentum flux and vertical wind speed, which are related to low-, mid- and high-frequency waves, respectively. The probability density function (PDF) distributions have similar shapes but show increasing disagreement with increasing intrinsic frequency. Since at those altitudes they are mainly caused by gravity waves, we also compare the geographic distribution of vertical wind fluctuations in the different products, which emphasizes the increase of both GW variance and intermittency with horizontal resolution. Finally, we quantify the fraction of resolved variability and its dependency on model resolution for the different variables. In all (re)analysis products, a significant part of the variability is still missing, especially at high frequencies, and should hence be parameterized. Among the two polar balloon datasets used, one was broadcast on the Global Telecommunication System for assimilation in NWP models, while the other consists of independent observations (unassimilated in the reanalyses). Comparing the Lagrangian spectra between the two campaigns shows that the (re)analyses are largely influenced by balloon data assimilation, which especially enhances the variance at low GW frequency. © 2020 Author(s).
语种	英语
scopus关键词	atmospheric modeling; gravity wave; Lagrangian analysis; stratosphere-troposphere interaction; wave dispersion; wave spectrum; wind field; Antarctica
来源期刊	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/141168
作者单位	Laboratoire de Météorologie Dynamique (LMD/IPSL), École Polytechnique, Institut Polytechnique de Paris, Sorbonne Université, École Normale Supérieure, PSL Research University, CNRS, Paris, France; Forschungszentrum Jülich (IEK-7: Stratosphere), Jülich, Germany
推荐引用方式 GB/T 7714	Podglajen A.,Hertzog A.,Plougonven R.,et al. Lagrangian gravity wave spectra in the lower stratosphere of current (re)analyses[J],2020,20(15).
APA	Podglajen A.,Hertzog A.,Plougonven R.,&Legras B..(2020).Lagrangian gravity wave spectra in the lower stratosphere of current (re)analyses.Atmospheric Chemistry and Physics,20(15).
MLA	Podglajen A.,et al."Lagrangian gravity wave spectra in the lower stratosphere of current (re)analyses".Atmospheric Chemistry and Physics 20.15(2020).