气候变化领域集成服务门户(CCPortal): Stratospheric gravity waves over the mountainous island of South Georgia: Testing a high-resolution dynamical model with 3-D satellite observations and radiosondes

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DOI	10.5194/acp-21-7695-2021
	Stratospheric gravity waves over the mountainous island of South Georgia: Testing a high-resolution dynamical model with 3-D satellite observations and radiosondes
	Hindley N.P.; Wright C.J.; Gadian A.M.; Hoffmann L.; Hughes J.K.; Jackson D.R.; King J.C.; Mitchell N.J.; Moffat-Griffin T.; Moss A.C.; Vosper S.B.; Ross A.N.
发表日期	2021
ISSN	1680-7316
起始页码	7695
结束页码	7722
卷号	21 期号:10
英文摘要	Atmospheric gravity waves (GWs) play an important role in atmospheric dynamics but accurately representing them in general circulation models (GCMs) is challenging. This is especially true for orographic GWs generated by wind flow over small mountainous islands in the Southern Ocean. Currently, these islands lie in the grey zone of global model resolution, where they are neither fully resolved nor fully parameterised. It is expected that as GCMs approach the spatial resolution of current high-resolution localarea models, small-island GW sources may be resolved without the need for parameterisations. But how realistic are the resolved GWs in these high-resolution simulations compared to observations? Here, we test a high-resolution (1.5 km horizontal grid, 118 vertical levels) local-area configuration of the Met Office Unified Model over the mountainous island of South Georgia (54 S, 36 W), running without GW parameterisations. The island's orography is well resolved in the model, and real-time boundary conditions are used for two time periods during July 2013 and June-July 2015.We compare simulated GWs in the model to coincident 3-D satellite observations from the Atmospheric Infrared Sounder (AIRS) on board Aqua. By carefully sampling the model using the AIRS resolution and measurement footprints (denoted as model sampled as AIRS hereafter), we present the first likefor- like comparison of simulated and observed 3-D GW amplitudes, wavelengths and directional GW momentum flux (GWMF) over the island using a 3-D S-transform method. We find that the timing, magnitude and direction of simulated GWMF over South Georgia are in good general agreement with observations, once the AIRS sampling and resolution are applied to the model. Area-averaged zonal GWMF during these 2 months is westward at around 5.3 and 5.6mPa in AIRS and model sampled as AIRS datasets respectively, but values directly over the island can exceed 50 mPa. However, up to 35% of the total GWMF in AIRS is actually found upwind of the island compared to only 17% in the model sampled as AIRS, suggesting that non-orographic GWs observed by AIRS may be underestimated in our model configuration. Meridional GWMF results show a small northward bias (20 %) in the model sampled as AIRS that may correspond to a southward wind bias compared to coincident radiosonde measurements. Finally, we present one example of large-amplitude (T 0 15-20K at 45 km altitude) GWs at short horizontal wavelengths (H 30-40 km) directly over the island in AIRS measurements that show excellent agreement with the model sampled as AIRS. This suggests that orographic GWs in the full-resolution model with T 0 45K and H 30-40 km can occur in reality. Our study demonstrates that not only can high-resolution local-area models simulate realistic stratospheric GWs over small mountainous islands but the application of satellite sampling and resolution to these models can also be a highly effective method for their validation. © 2021 Copernicus GmbH. All rights reserved.
语种	英语
scopus关键词	atmospheric dynamics; general circulation model; gravity wave; radiosonde; stratosphere; three-dimensional modeling; zonal wind; Antarctica; South Georgia
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/246877
作者单位	Centre for Space, Atmospheric and Oceanic Science, University of Bath, Bath, United Kingdom; School of Earth and Environment, University of Leeds, Leeds, United Kingdom; Jülich Supercomputing Centre, Forschungszentrum Jülich, Jülich, Germany; Met Office, Exeter, United Kingdom; Atmosphere, Ice and Climate Group, British Antarctic Survey, Cambridge, United Kingdom
推荐引用方式 GB/T 7714	Hindley N.P.,Wright C.J.,Gadian A.M.,et al. Stratospheric gravity waves over the mountainous island of South Georgia: Testing a high-resolution dynamical model with 3-D satellite observations and radiosondes[J],2021,21(10).
APA	Hindley N.P..,Wright C.J..,Gadian A.M..,Hoffmann L..,Hughes J.K..,...&Ross A.N..(2021).Stratospheric gravity waves over the mountainous island of South Georgia: Testing a high-resolution dynamical model with 3-D satellite observations and radiosondes.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(10).
MLA	Hindley N.P.,et al."Stratospheric gravity waves over the mountainous island of South Georgia: Testing a high-resolution dynamical model with 3-D satellite observations and radiosondes".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.10(2021).