Iodine chemistry in the eastern Pacific marine boundary layer
| Autor: | Carlos Ordóñez, E. Leedham, David E. Oram, Anoop S. Mahajan, Alfonso Saiz-Lopez, J. Francisco Paredes Mora, John M. C. Plane, S. M. MacDonald, C. Prados-Roman, Juan Carlos Gómez Martín, T. D. Hay, Mario V. Agama Reyes, Manuel Gil, Mar Sorribas |
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| Rok vydání: | 2013 |
| Předmět: |
chemistry.chemical_classification
Atmospheric Science Ozone 010504 meteorology & atmospheric sciences Chemistry Differential optical absorption spectroscopy Iodide 010501 environmental sciences Annual cycle Atmospheric sciences 01 natural sciences Ozone depletion Aerosol Trace gas Sea surface temperature chemistry.chemical_compound Geophysics 13. Climate action Space and Planetary Science Earth and Planetary Sciences (miscellaneous) 14. Life underwater 0105 earth and related environmental sciences |
| Zdroj: | Journal of Geophysical Research: Atmospheres. 118:887-904 |
| ISSN: | 2169-897X |
| DOI: | 10.1002/jgrd.50132 |
| Popis: | [1] 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 Galapagos 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. |
| Databáze: | OpenAIRE |
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