气候变化领域集成服务门户(CCPortal): The semiannual oscillation (SAO) in the tropical middle atmosphere and its gravity wave driving in reanalyses and satellite observations

CCPortal

DOI	10.5194/acp-21-13763-2021
	The semiannual oscillation (SAO) in the tropical middle atmosphere and its gravity wave driving in reanalyses and satellite observations
	Ern M.; Diallo M.; Preusse P.; Mlynczak M.G.; Schwartz M.J.; Wu Q.; Riese M.
发表日期	2021
ISSN	1680-7316
起始页码	13763
结束页码	13795
卷号	21 期号:18
英文摘要	Gravity waves play a significant role in driving the semiannual oscillation (SAO) of the zonal wind in the tropics. However, detailed knowledge of this forcing is missing, and direct estimates from global observations of gravity waves are sparse. For the period 2002-2018, we investigate the SAO in four different reanalyses: ERA-Interim, JRA-55, ERA-5, and MERRA-2. Comparison with the SPARC zonal wind climatology and quasi-geostrophic winds derived from Microwave Limb Sounder (MLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite observations show that the reanalyses reproduce some basic features of the SAO. However, there are also large differences, depending on the model setup. Particularly, MERRA-2 seems to benefit from dedicated tuning of the gravity wave drag parameterization and assimilation of MLS observations. To study the interaction of gravity waves with the background wind, absolute values of gravity wave momentum fluxes and a proxy for absolute gravity wave drag derived from SABER satellite observations are compared with different wind data sets: The SPARC wind climatology; data sets combining ERA-Interim at low altitudes and MLS or SABER quasi-geostrophic winds at high altitudes; and data sets that combine ERA-Interim, SABER quasi-geostrophic winds, and direct wind observations by the TIMED Doppler Interferometer (TIDI). In the lower and middle mesosphere the SABER absolute gravity wave drag proxy correlates well with positive vertical gradients of the background wind, indicating that gravity waves contribute mainly to the driving of the SAO eastward wind phases and their downward propagation with time. At altitudes 75-85 km, the SABER absolute gravity wave drag proxy correlates better with absolute values of the background wind, suggesting a more direct forcing of the SAO winds by gravity wave amplitude saturation. Above about 80 km SABER gravity wave drag is mainly governed by tides rather than by the SAO. The reanalyses reproduce some basic features of the SAO gravity wave driving: All reanalyses show stronger gravity wave driving of the SAO eastward phase in the stratopause region. For the higher-top models ERA-5 and MERRA-2, this is also the case in the lower mesosphere. However, all reanalyses are limited by model-inherent damping in the upper model levels, leading to unrealistic features near the model top. Our analysis of the SABER and reanalysis gravity wave drag suggests that the magnitude of SAO gravity wave forcing is often too weak in the free-running general circulation models; therefore, a more realistic representation is needed. © 2021 Manfred Ern et al.
语种	英语
scopus关键词	annual variation; atmospheric dynamics; climate oscillation; climatology; drag; general circulation model; gravity wave; microwave limb sounder; middle atmosphere; parameterization; quasi-geostrophic flow; satellite data; tropical region; wave field
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/246579
作者单位	Institut für Energie-und Klimaforschung-Stratosphäre (IEK-7), Forschungszentrum Jülich GmbH, Jülich, 52425, Germany; NASA Langley Research Center, Hampton, VA, United States; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States; National Center for Atmospheric Research, High Altitude Observatory, Boulder, CO, United States
推荐引用方式 GB/T 7714	Ern M.,Diallo M.,Preusse P.,et al. The semiannual oscillation (SAO) in the tropical middle atmosphere and its gravity wave driving in reanalyses and satellite observations[J],2021,21(18).
APA	Ern M..,Diallo M..,Preusse P..,Mlynczak M.G..,Schwartz M.J..,...&Riese M..(2021).The semiannual oscillation (SAO) in the tropical middle atmosphere and its gravity wave driving in reanalyses and satellite observations.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(18).
MLA	Ern M.,et al."The semiannual oscillation (SAO) in the tropical middle atmosphere and its gravity wave driving in reanalyses and satellite observations".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.18(2021).