HCOOH in the remote atmosphere: Constraints from Atmospheric Tomography (ATom) airborne observations.

Autor: Chen X; Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN 55108., Millet DB; Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN 55108., Neuman JA; NOAA Chemical Sciences Laboratory, Boulder, CO 80305.; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309., Veres PR; NOAA Chemical Sciences Laboratory, Boulder, CO 80305., Ray EA; NOAA Chemical Sciences Laboratory, Boulder, CO 80305.; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309., Commane R; Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory, Columbia University, New York, NY 10964., Daube BC; Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138., McKain K; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309.; NOAA Global Monitoring Laboratory, Boulder, CO 80305., Schwarz JP; NOAA Chemical Sciences Laboratory, Boulder, CO 80305., Katich JM; NOAA Chemical Sciences Laboratory, Boulder, CO 80305.; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309., Froyd KD; NOAA Chemical Sciences Laboratory, Boulder, CO 80305.; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309., Schill GP; NOAA Chemical Sciences Laboratory, Boulder, CO 80305.; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309., Kim MJ; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125., Crounse JD; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125., Allen HM; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125., Apel EC; Atmospheric Chemistry Observations & Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80307., Hornbrook RS; Atmospheric Chemistry Observations & Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80307., Blake DR; Department of Chemistry, University of California, Irvine, CA 92697., Nault BA; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309.; Department of Chemistry, University of Colorado Boulder, Boulder, CO 80309., Campuzano-Jost P; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309.; Department of Chemistry, University of Colorado Boulder, Boulder, CO 80309., Jimenez JL; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309.; Department of Chemistry, University of Colorado Boulder, Boulder, CO 80309., Dibb JE; Earth Systems Research Center/EOS, University of New Hampshire, Durham, NH 03824.
Jazyk: angličtina
Zdroj: ACS earth & space chemistry [ACS Earth Space Chem] 2021 Jun 17; Vol. 5 (6), pp. 1436-1454. Date of Electronic Publication: 2021 May 13.
DOI: 10.1021/acsearthspacechem.1c00049
Abstrakt: Formic acid (HCOOH) is an important component of atmospheric acidity but its budget is poorly understood, with prior observations implying substantial missing sources. Here we combine pole-to-pole airborne observations from the Atmospheric Tomography Mission (ATom) with chemical transport model (GEOS-Chem CTM) and back trajectory analyses to provide the first global in-situ characterization of HCOOH in the remote atmosphere. ATom reveals sub-100 ppt HCOOH concentrations over most of the remote oceans, punctuated by large enhancements associated with continental outflow. Enhancements correlate with known combustion tracers and trajectory-based fire influences. The GEOS-Chem model underpredicts these in-plume HCOOH enhancements, but elsewhere we find no broad indication of a missing HCOOH source in the background free troposphere. We conclude that missing non-fire HCOOH precursors inferred previously are predominantly short-lived. We find indications of a wet scavenging underestimate in the model consistent with a positive HCOOH bias in the tropical upper troposphere. Observations reveal episodic evidence of ocean HCOOH uptake, which is well-captured by GEOS-Chem; however, despite its strong seawater undersaturation HCOOH is not consistently depleted in the remote marine boundary layer. Over fifty fire and mixed plumes were intercepted during ATom with widely varying transit times and source regions. HCOOH:CO normalized excess mixing ratios in these plumes range from 3.4 to >50 ppt/ppb CO and are often over an order of magnitude higher than expected primary emission ratios. HCOOH is thus a major reactive organic carbon reservoir in the aged plumes sampled during ATom, implying important missing pathways for in-plume HCOOH production.
Databáze: MEDLINE