气候变化领域集成服务门户(CCPortal): Characterizing model errors in chemical transport modeling of methane: Using GOSAT XCH4 data with weak-constraint four-dimensional variational data assimilation

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DOI	10.5194/acp-21-9545-2021
	Characterizing model errors in chemical transport modeling of methane: Using GOSAT XCH4 data with weak-constraint four-dimensional variational data assimilation
	Stanevich I.; Jones D.B.A.; Strong K.; Keller M.; Henze D.K.; Parker R.J.; Boesch H.; Wunch D.; Notholt J.; Petri C.; Warneke T.; Sussmann R.; Schneider M.; Hase F.; Kivi R.; Deutscher N.M.; Velazco V.A.; Walker K.A.; Deng F.
发表日期	2021
ISSN	1680-7316
起始页码	9545
结束页码	9572
卷号	21 期号:12
英文摘要	We examined biases in the global GEOS-Chem chemical transport model for the period of February-May 2010 using weak-constraint (WC) four-dimensional variational (4D-Var) data assimilation and dry-air mole fractions of CH4 (XCH4) from the Greenhouse gases Observing SATellite (GOSAT). The ability of the observations and the WC 4D-Var method to mitigate model errors in CH4 concentrations was first investigated in a set of observing system simulation experiments (OSSEs). We then assimilated the GOSAT XCH4 retrievals and found that they were capable of providing information on the vertical structure of model errors and of removing a significant portion of biases in the modeled CH4 state. In the WC 4D-Var assimilation, corrections were added to the modeled CH4 state at each model time step to account for model errors and improve the model fit to the assimilated observations. Compared to the conventional strong-constraint (SC) 4D-Var assimilation, the WC method was able to significantly improve the model fit to independent observations. Examination of the WC state corrections suggested that a significant source of model errors was associated with discrepancies in the model CH4 in the stratosphere. The WC state corrections also suggested that the model vertical transport in the troposphere at middle and high latitudes is too weak. The problem was traced back to biases in the uplift of CH4 over the source regions in eastern China and North America. In the tropics, the WC assimilation pointed to the possibility of biased CH4 outflow from the African continent to the Atlantic in the mid-troposphere. The WC assimilation in this region would greatly benefit from glint observations over the ocean to provide additional constraints on the vertical structure of the model errors in the tropics. We also compared the WC assimilation at 4g ×g5 and 2g ×g2.5 horizontal resolutions and found that the WC corrections to mitigate the model errors were significantly larger at 4g ×g5 than at 2g ×g2.5 resolution, indicating the presence of resolution-dependent model errors. Our results illustrate the potential utility of the WC 4D-Var approach for characterizing model errors. However, a major limitation of this approach is the need to better characterize the specified model error covariance in the assimilation scheme. © 2021 Ilya Stanevich et al.
语种	英语
scopus关键词	atmospheric chemistry; atmospheric transport; chemical analysis; concentration (composition); data assimilation; error analysis; four-dimensional modeling; methane; troposphere
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/246786
作者单位	Department of Physics, University of Toronto, Toronto, ON, Canada; Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, United States; California Institute of Technology, Pasadena, CA, United States; Earth Observation Science, Department of Physics and Astronomy, University of Leicester, Leicester, United Kingdom; National Centre for Earth Observation (NCEO), University of Leicester, Leicester, United Kingdom; Institute of Environmental Physics, University of Bremen, Bremen, Germany; Institute of Meteorology and Climate Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Garmisch-Partenkirchen, Germany; Institute of Meteorology and Climate Research (IMK-ASF), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Finnish Meteorological Institute, Sodankylä, Finland; Centre for Atmospheric Chemistry, School of Chemistry, University of Wollongong, Wollongong, NSW, Australia
推荐引用方式 GB/T 7714	Stanevich I.,Jones D.B.A.,Strong K.,et al. Characterizing model errors in chemical transport modeling of methane: Using GOSAT XCH4 data with weak-constraint four-dimensional variational data assimilation[J],2021,21(12).
APA	Stanevich I..,Jones D.B.A..,Strong K..,Keller M..,Henze D.K..,...&Deng F..(2021).Characterizing model errors in chemical transport modeling of methane: Using GOSAT XCH4 data with weak-constraint four-dimensional variational data assimilation.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(12).
MLA	Stanevich I.,et al."Characterizing model errors in chemical transport modeling of methane: Using GOSAT XCH4 data with weak-constraint four-dimensional variational data assimilation".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.12(2021).