Iodine chemistry in the eastern Pacific marine boundary layer

Gómez Martín, Juan C., Mahajan, Anoop S., Hay, Timothy D., Prados-Román, Cristina, Ordóñez, Carlos, MacDonald, Samantha M., Plane, John M.C., Sorribas, Mar, Gil, Manuel, Paredes Mora, J. Francisco, Agama Reyes, Mario V., Oram, David E., Leedham, Emma ORCID: https://orcid.org/0000-0002-6993-1271 and Saiz-Lopez, Alfonso (2013) Iodine chemistry in the eastern Pacific marine boundary layer. Journal of Geophysical Research: Atmospheres, 118 (2). pp. 887-904. ISSN 2169-897X

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Abstract

Observations of gas-phase iodine species were made during a field campaign in the eastern Pacific marine boundary layer (MBL). The Climate and Halogen Reactivity Tropical Experiment (CHARLEX) in the Galápagos Islands, running from September 2010 to present, is the first long-term ground-based study of trace gases in this region. Observations of gas-phase iodine species were made using long-path differential optical absorption spectroscopy (LP-DOAS), multi-axis DOAS (MAX-DOAS), and resonance and off-resonance fluorescence by lamp excitation (ROFLEX). These measurements were supported by ancillary measurements of ozone, nitrogen oxides, and meteorological variables. Selective halocarbon and ultrafine aerosol concentration measurements were also made. MAX-DOAS observations of iodine monoxide (IO) display a weak seasonal variation. The maximum differential slant column density was 3.8 × 1013 molecule cm−2 (detection limit ~7 × 1012 molecule cm−2). The seasonal variation of reactive iodine IOx (= I + IO) is stronger, peaking at 1.6 pptv during the warm season (February–April). This suggests a dependence of the iodine sources on the annual cycle in sea surface temperature, although perturbations by changes in ocean surface iodide concentration and solar radiation are also possible. An observed negative correlation of IOx with chlorophyll-a indicates a predominance of abiotic sources. The low IO mixing ratios measured (below the LP-DOAS detection limit of 0.9 pptv) are not consistent with satellite observations if IO is confined to the MBL. The IOx loading is consistent with the observed absence of strong ozone depletion and nucleation events, indicating a small impact of iodine chemistry on these climatically relevant factors in the eastern Pacific MBL.

Item Type:	Article
Uncontrolled Keywords:	iodine,halogen chemistry, ocean emissions,marine boundary layer,new particle formation,ozone depletion,sdg 12 - responsible consumption and production,sdg 14 - life below water ,/dk/atira/pure/sustainabledevelopmentgoals/responsible_consumption_and_production
Faculty \ School:	Faculty of Science > School of Environmental Sciences
Depositing User:	Pure Connector
Date Deposited:	03 Mar 2014 18:10
Last Modified:	31 Oct 2022 14:30
URI:	https://ueaeprints.uea.ac.uk/id/eprint/47852
DOI:	10.1002/jgrd.50132

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