Toward a chemical reanalysis in a coupled chemistry-climate model: An evaluation of MOPITT CO assimilation and its impact on tropospheric composition
Arellano, A. F.
Worden, H. M.
Emmons, L. K.
Buchholz, R. R.
Anderson, J. L.
Martinez Alonso, S.
Edwards, D. P.
Andreae, M. O.
Hannigan, J. W.
AffiliationUniv Arizona, Dept Atmospher Sci
MetadataShow full item record
PublisherAMER GEOPHYSICAL UNION
CitationToward a chemical reanalysis in a coupled chemistry-climate model: An evaluation of MOPITT CO assimilation and its impact on tropospheric composition 2016, 121 (12):7310 Journal of Geophysical Research: Atmospheres
Rights©2016. American Geophysical Union. All Rights Reserved.
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AbstractWe examine in detail a 1 year global reanalysis of carbon monoxide (CO) that is based on joint assimilation of conventional meteorological observations and Measurement of Pollution in The Troposphere (MOPITT) multispectral CO retrievals in the Community Earth System Model (CESM). Our focus is to assess the impact to the chemical system when CO distribution is constrained in a coupled full chemistry-climate model like CESM. To do this, we first evaluate the joint reanalysis (MOPITT Reanalysis) against four sets of independent observations and compare its performance against a reanalysis with no MOPITT assimilation (Control Run). We then investigate the CO burden and chemical response with the aid of tagged sectoral CO tracers. We estimate the total tropospheric CO burden in 2002 (from ensemble mean and spread) to be 371 +/- 12% Tg for MOPITT Reanalysis and 291 +/- 9% Tg for Control Run. Our multispecies analysis of this difference suggests that (a) direct emissions of CO and hydrocarbons are too low in the inventory used in this study and (b) chemical oxidation, transport, and deposition processes are not accurately and consistently represented in the model. Increases in CO led to net reduction of OH and subsequent longer lifetime of CH4 (Control Run: 8.7 years versus MOPITT Reanalysis: 9.3 years). Yet at the same time, this increase led to 5-10% enhancement of Northern Hemisphere O-3 and overall photochemical activity via HOx recycling. Such nonlinear effects further complicate the attribution to uncertainties in direct emissions alone. This has implications to chemistry- climate modeling and inversion studies of longer-lived species.
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VersionFinal published version
SponsorsINSU-CNRS (France); Meteo-France; CNES; Universite Paul Sabatier (Toulouse, France); Research Center Julich (FZJ, Julich, Germany); EU; National Aeronautics and Space Administration (NASA); NSF Office of Polar Programs (OPP); Danish Meteorological Institute; Australian Research Council [DP110101948, LE0668470]; European Commission; Max Planck Society; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo; Conselho Nacional de Desenvolvimento Cientifico (Instituto do Milenio LBA); National Science Foundation; National Science Foundation [Computational and Information Systems Laboratory]; Office of Science (BER) of the U.S. Department of Energy; NASA; NASA [NNX13AK24G, NNX14AN47G]