Formaldehyde in the tropical western pacific: Chemical sources and sinks, convective transport, and representation in CAM-Chem and the CCMI models

Formaldehyde (HCHO) directly affects the atmospheric oxidative capacity through its effects onHOx. In remote marine environments, such as the tropical western Pacific (TWP), it is particularly importantto understand the processes controlling the abundance of HCHO because model output from these regions isused to correct satellite retrievals of HCHO. Here we have used observations from the Convective Transport ofActive Species in the Tropics (CONTRAST)field campaign, conducted during January and February 2014, toevaluate our understanding of the processes controlling the distribution of HCHO in the TWP as well as itsrepresentation in chemical transport/climate models. Observed HCHO mixing ratios varied from ~500 partsper trillion by volume (pptv) near the surface to ~75 pptv in the upper troposphere. Recent convectivetransport of near surface HCHO and its precursors, acetaldehyde and possibly methyl hydroperoxide,increased upper tropospheric HCHO mixing ratios by ~33% (22 pptv); this air contained roughly 60% less NOthan more aged air.Output from the CAM-Chem chemistry transport model (2014 meteorology)as well asninechemistry climate models from the Chemistry-Climate Model Initiative (free-running meteorology) are foundto uniformly underestimate HCHO columns derived from in situ observations by between 4 and 50%. Thisunderestimate of HCHO likely results from a near factor of two underestimate of NO in most models, whichstrongly suggests errors in NOxemissions inventories and/or in the model chemical mechanisms. Likewise, thelack of oceanic acetaldehyde emissions and potential errors in the model acetaldehyde chemistry lead toadditional underestimates in modeled HCHO of up to 75 pptv (~15%) in the lower troposphere.Fil: Anderson, Daniel C.. University of Maryland. Department of Atmospheric and Oceanic Science; Estados UnidosFil: Nicely, Julie M.. University of Maryland. Department of Atmospheric and Oceanic Science; Estados Unidos. University Space Research; Estados UnidosFil: Wolfe, Glenn M.. University of Maryland. Department of Atmospheric and Oceanic Science; Estados Unidos. National Aeronautics and Space Administration; Estados UnidosFil: Hanisco, Thomas F.. National Aeronautics and Space Administration; Estados UnidosFil: Salawitch, Ross J.. University of Maryland. Department of Atmospheric and Oceanic Science; Estados UnidosFil: Canty, Timothy P.. University of Maryland. Department of Atmospheric and Oceanic Science; Estados UnidosFil: Dickerson, Russell R.. University of Maryland. Department of Atmospheric and Oceanic Science; Estados UnidosFil: Apel, Eric C.. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Baidar, Sunil. State University of Colorado at Boulder; Estados Unidos. Cooperative Institute for Research in Environmental Sciences; Estados UnidosFil: Bannan, Thomas J.. University of Manchester; Reino UnidoFil: Blake, Nicola J.. University of California; Estados UnidosFil: Chen, Dexian. Georgia Institute of Techology; Estados UnidosFil: Dix, Barbara. State University of Colorado at Boulder; Estados UnidosFil: Fernandez, Rafael Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Institute of Physical Chemistry Rocasolano,; EspañaFil: Hall, Samuel R.. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Hornbrook, Rebecca S.. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Huey, L. Gregory. Georgia Institute of Techology; Estados UnidosFil: Josse, Beatrice. Centre National de Recherche Météorologique; FranciaFil: Jöckel, Patrick. Deutsches Zentrum für Luft‐ und Raumfahrt, Institut für Physik der Atmosphäre; AlemaniaFil: Kinnison, Douglas E.. National Center for Atmospheric Research; Estados UnidosFil: Koenig, Theodore K.. State University of Colorado at Boulder; Estados UnidosFil: Le Breton, Michael. University of Gothenburg; SueciaFil: Marécal, Virginie. Centre National de Recherche Météorologique; FranciaFil: Morgenstern, Olaf. National Institute of Water and Atmospheric Research; Nueva ZelandaFil: Oman, Luke D.. National Aeronautics and Space Administration; Estados UnidosFil: Pan, Laura L.. National Center for Atmospheric Research; Estados UnidosFil: Percival, Carl. University of Manchester; Reino UnidoFil: Plummer, David. Canadian Centre for Climate Modeling and Analysis; CanadáFil: Revell, Laura E.. Institute for Atmospheric and Climate Science; SuizaFil: Rozanov, Eugene. Physikalisch-meteorologisches Observatorium Davos World Radiation Center; SuizaFil: Saiz-lopez, Alfonso. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Stenke, Andrea. Eth Zürich; SuizaFil: Sudo, Kengo. Japan Agency For Marin-earth Science And Technology; JapónFil: Tilmes, Simone. National Center for Atmospheric Research; Estados UnidosFil: Ullmann, Kirk. National Center for Atmospheric Research; Estados UnidosFil: Volkamer, Rainer. State University of Colorado at Boulder; Estados UnidosFil: Weinheimer, Andrew J.. National Center for Atmospheric Research; Estados UnidosFil: Zeng, Guang. National Institute Of Water And Atmospheric Research; Nueva Zeland