Observations of I&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; at a remote marine site

Lawler, Michael J.; Mahajan, Anoop S.; Saiz‐Lopez, Alfonso; Saltzman, E. S.

doi:10.5194/acp-14-2669-2014

Cited by 34 publications

(57 citation statements)

References 35 publications

(49 reference statements)

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“…Additionally, the measured emission rates of iodinated VOCs are unable to explain the observed levels of IO and I 2 Jones et al, 2010b;Großmann et al, 2013;Lawler et al, 2014). Several mechanisms have been introduced to explain the observations and are still under active discussion (e.g.…”

Section: P S Monks Et Al: Tropospheric Ozone and Its Precursorsmentioning

confidence: 99%

“…Several mechanisms have been introduced to explain the observations and are still under active discussion (e.g. Lawler et al, 2014;Carpenter et al, 2013;MacDonald et al, 2014). Some of these discrepancies may be explained by assuming seasonal or yearly cycles of the iodine sources, but there are also several uncertainties in the iodine chemical mechanism Saiz-Lopez et al, 2012b).…”

Section: P S Monks Et Al: Tropospheric Ozone and Its Precursorsmentioning

confidence: 99%

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Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

et al. 2015

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Abstract. Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a byproduct of the very oxidation chemistry it largely initiates. Much effort is focused on the reduction of surface levels of ozone owing to its health and vegetation impacts, but recent efforts to achieve reductions in exposure at a country scale have proved difficult to achieve owing to increases in background ozone at the zonal hemispheric scale. There is also a growing realisation that the role of ozone as a short-lived climate pollutant could be important in integrated air quality climate change mitigation. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models. It takes the view that knowledge across the scales is important for dealing with air quality and climate change in a synergistic manner. The review shows that there remain a number of clear challenges for ozone such as explaining surface trends, incorporating new chemical understanding, ozone-climate coupling, and a better assessment of impacts. There is a clear and present need to treat ozone across the range of scales, a transboundary issue, but with an emphasis on the hemispheric scales. New observational opportunities are offered both by satellites and small sensors that bridge the scales.

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Section: P S Monks Et Al: Tropospheric Ozone and Its Precursorsmentioning

confidence: 99%

Section: P S Monks Et Al: Tropospheric Ozone and Its Precursorsmentioning

confidence: 99%

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

et al. 2015

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“…Very recently the first measurements of I 2 at a remote marine site (Cape Verde) have been reported (Lawler et al, 2014), with night time mixing ratios of up to 1.7 pptv. These mixing ratios are not enough to sustain the levels of IO observed at Cape Verde , which concurs with our laboratory observations of HOI being the major species emitted from the ocean surface.…”

Section: Introductionmentioning

confidence: 99%

A laboratory characterisation of inorganic iodine emissions from the sea surface: dependence on oceanic variables and parameterisation for global modelling

et al. 2014

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Abstract.Reactive iodine compounds play a significant role in the atmospheric chemistry of the oceanic boundary layer by influencing the oxidising capacity through catalytically removing O 3 and altering the HO x and NO x balance. The sea-to-air flux of iodine over the open ocean is therefore an important quantity in assessing these impacts on a global scale. This paper examines the effect of a number of relevant environmental parameters, including water temperature, salinity and organic compounds, on the magnitude of the HOI and I 2 fluxes produced from the uptake of O 3 and its reaction with iodide ions in aqueous solution. The results of these laboratory experiments and those reported previously , along with sea surface iodide concentrations measured or inferred from measurements of dissolved total iodine and iodate reported in the literature, were then used to produce parameterised expressions for the HOI and I 2 fluxes as a function of wind speed, sea-surface temperature and O 3 . These expressions were used in the Tropospheric HAlogen chemistry MOdel (THAMO) to compare with MAX-DOAS measurements of iodine monoxide (IO) performed during the HaloCAST-P cruise in the eastern Pacific ocean . The modelled IO agrees reasonably with the field observations, although significant discrepancies are found during a period of low wind speeds (< 3 m s −1 ), when the model overpredicts IO by up to a factor of 3. The inorganic iodine flux contributions to IO are found to be comparable to, or even greater than, the contribution of organo-iodine compounds and therefore its inclusion in atmospheric models is important to improve predictions of the influence of halogen chemistry in the marine boundary layer.

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“…Since then, several studies have aimed at determining the source gases of iodine and their chemical pathways (see Saiz-Lopez et al, 2012a, and references therein). While emissions of very short-lived (VSL) organic source gases (CH 3 I, CH 2 I 2 , CH 2 ICl and CH 2 IBr) have been observed in supersaturated waters (Carpenter et al, 2012), the existence of an abiotic ocean source of iodine has been directly and indirectly inferred throughout scattered field campaigns and 1-D model works (Read et al, 2008;Jones et al, 2010;Mahajan et al, 2010Mahajan et al, , 2012Gómez Martín et al, 2013;Großman et al, 2013;Lawler et al, 2014). Very recently, laboratory studies have demonstrated the potential of the ocean to emit inorganic hypoiodous acid (HOI) and, to a lesser extent, molecular iodine (I 2 ) following the reaction of ozone with iodide at the sea surface (Carpenter et al, 2013;MacDonald et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

A negative feedback between anthropogenic ozone pollution and enhanced ocean emissions of iodine

et al. 2015

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Abstract. Naturally emitted from the oceans, iodine compounds efficiently destroy atmospheric ozone and reduce its positive radiative forcing effects in the troposphere. Emissions of inorganic iodine have been experimentally shown to depend on the deposition to the oceans of tropospheric ozone, whose concentrations have significantly increased since 1850 as a result of human activities. A chemistry-climate model is used herein to quantify the current ocean emissions of inorganic iodine and assess the impact that the anthropogenic increase in tropospheric ozone has had on the natural cycle of iodine in the marine environment since pre-industrial times. Our results indicate that the human-driven enhancement of tropospheric ozone has doubled the oceanic inorganic iodine emissions following the reaction of ozone with iodide at the sea surface. The consequent build-up of atmospheric iodine, with maximum enhancements of up to 70 % with respect to pre-industrial times in continental pollution outflow regions, has in turn accelerated the ozone chemical loss over the oceans with strong spatial patterns. We suggest that this ocean-atmosphere interaction represents a negative geochemical feedback loop by which current ocean emissions of iodine act as a natural buffer for ozone pollution and its radiative forcing in the global marine environment.

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Observations of I<sub>2</sub> at a remote marine site

Cited by 34 publications

References 35 publications

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

A laboratory characterisation of inorganic iodine emissions from the sea surface: dependence on oceanic variables and parameterisation for global modelling

A negative feedback between anthropogenic ozone pollution and enhanced ocean emissions of iodine

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