Observations of iodine oxide in the Indian Ocean marine boundary layer: A transect from the tropics to the high latitudes

Mahajan, Anoop S.; Tinel, Liselotte; Hulswar, Shrivardhan; Cuevas, Carlos A.; Wang, Shanshan; Ghude, Sachin D.; Naik, Ravidas K.; Mishra, Rajani Kanta; Sabu, P.; Sarkar, Amit; Anilkumar, N.; Lopez, A.

doi:10.1016/j.aeaoa.2019.100016

Cited by 16 publications

(31 citation statements)

References 60 publications

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“…For example, the sea-air flux of HOI and I2 could explain the observed levels of molecular iodine and IO at Cape Verde (Lawler et al, 2014b), and observed IO levels over the eastern Pacific were in reasonable agreement with those modelled from estimated I2 and HOI fluxes (MacDonald et al, 2014). In contrast, the inorganic iodine fluxes estimated for the Indian Ocean and Indian sector of the Southern Ocean marine boundary layer could not fully explain the observed IO concentrations (Mahajan et al, 2019a(Mahajan et al, , 2019b.…”

Section: Introductionmentioning

confidence: 68%

“…For further analysis we also include IO observations from the 2 nd International Indian Ocean Expedition (IIOE-2) and the 8 th Indian Southern Ocean Expedition (ISOE-8) conducted in the Indian and Southern Ocean region during austral summer of 2014-2015 (Mahajan et al, 2019a(Mahajan et al, , 2019b. We also include SSI observations in the northern Indian Ocean from two expeditions namely, the Sagar Kanya-333 cruise (SK-333) and the Bay of Bengal Boundary Layer Experiment (BoBBLE) conducted during June-July and September 2016 respectively (Chance et al, 2019b).…”

Section: Measurement Techniques and Methodologymentioning

confidence: 99%

“…The track of the ship during ISOE-9 along with the air mass back trajectories arriving at noon each day is given in the supplementary text (Rolph et al, 2017;Stein et al, 2015) was used to calculate the back trajectories. Similar back trajectory plots and full cruise tracks for ISOE-8 and IIOE-2 are given in Mahajan et al (2019aMahajan et al ( , 2019b. During the three expeditions, meteorological parameters of ocean and atmosphere were measured using an on-board automatic weather station and manual observation techniques.…”

Section: Measurement Techniques and Methodologymentioning

confidence: 99%

“…and December 2015) of the Southern Ocean were interpreted using parameterisations to estimate the SSI concentrations in combination with observed ozone concentrations, to subsequently calculate the resulting inorganic iodine fluxes. This approach suggested that the observed atmospheric IO may not be well correlated with the inorganic fluxes and that biogenic fluxes could play an important role (Mahajan et al, 2019a(Mahajan et al, , 2019b. Here, we present measurements of IO in the MBL of the Indian Ocean and the Southern Ocean during the 9 th Indian Southern Ocean Expedition (ISOE-9) conducted in January-February 2017, alongside the first simultaneous SSI observations along the cruise track (Chance et al, 2019a).…”

Section: Introductionmentioning

confidence: 94%

“…At present, there is a paucity of measurements of SSI, and remote sensing techniques cannot detect iodine species in seawater (Chance et al, 2014;Sherwen et al, 2019a). In particular, regions of the Indian Ocean and the Southern Ocean have been under-sampled in terms of iodine observations in the atmosphere and ocean (Chance et al, 2014;Mahajan et al, 2019aMahajan et al, , 2019b. It is important to remember that the most widely used parameterisation (MacDonald et al, 2014) is built on a limited observational dataset from the Atlantic and Pacific Ocean completely excluding the Indian Ocean and the Southern Ocean.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of Reactive Inorganic Iodine Fluxes in the Indian and Southern Ocean Marine Boundary Layer

Inamdar¹,

Tinel²,

Chance³

et al. 2020

Preprint

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Abstract. Iodine chemistry has noteworthysignificant impacts on the oxidising capacity of the marine boundary layer (MBL) through the depletion of ozone (O3) and changes to HOx (OH/HO2) and NOx (NO/NO2) ratios. Hitherto, studies have shown that the reaction of atmospheric O3 with surface seawater iodide (I−) contributes to the flux of iodine species into the MBL mainly as hypoiodous acid (HOI) and molecular iodine (I2). Here, we present the first concomitant observations of iodine oxide (IO), O3 in the gas phase, and sea surface iodide concentrations. The results from three field campaigns in the Indian Ocean and the Southern Ocean during 2014–2017 are used to compute reactive iodine fluxes to the MBL. Observations of atmospheric IO by MAX-DOAS show active iodine chemistry in this environment, with IO values up to 1 pptv (parts per trillion by volume) below latitudes of 40° S. In order to compute the sea-to-air iodine flux supporting this chemistry, we compare previously established global sea surface iodide parameterisations with new, region-specific parameterisations based on the new iodide observations. This study shows that regional changes in salinity and sea surface temperature play a role in surface seawater iodide estimation. Sea-air fluxes of HOI and I2, calculated from the atmospheric ozone and seawater iodide concentrations (observed and predicted), failed to adequately explain the detected IO in this region. This discrepancy highlights the need to measure direct fluxes of inorganic and organic iodine species in the marine environment. Amongst other potential drivers of reactive iodine chemistry investigated, chlorophyll-a showed a significant correlation with atmospheric IO (R = 0.7 above the 99 % significance level) to the north of the polar front. This correlation might be indicative of a biogenic control on iodine sources in this region.

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Section: Introductionmentioning

confidence: 68%

Section: Measurement Techniques and Methodologymentioning

confidence: 99%

Section: Measurement Techniques and Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Estimation of Reactive Inorganic Iodine Fluxes in the Indian and Southern Ocean Marine Boundary Layer

Inamdar¹,

Tinel²,

Chance³

et al. 2020

Preprint

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A review on air–sea exchange of reactive trace gases over the northern Indian Ocean

Gupta,

Tripathi,

Malik

et al. 2024

J Earth Syst Sci

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Role of Iodine Recycling on Sea‐Salt Aerosols in the Global Marine Boundary Layer

Tham

Fernández

et al. 2022

Geophysical Research Letters

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Heterogeneous uptake of hypoiodous acid (HOI), the dominant inorganic iodine species in the marine boundary layer (MBL), on sea‐salt aerosol (SSA) to form iodine monobromide and iodine monochloride has been adopted in models with assumed efficiency. Recently, field measurements have reported a much faster rate of this recycling process than previously assumed in models. Here, we conduct global model simulations to quantify the range of effects of iodine recycling within the MBL, using Conventional, Updated, and Upper‐limit coefficients. When considering the Updated coefficient, iodine recycling significantly enhances gaseous inorganic iodine abundance (∼40%), increases halogen atom production rates (∼40% in I, >100% in Br, and ∼60% in Cl), and reduces oxidant levels (−7% in O3, −2% in OH, and −4% in HO2) compared to the simulation without the process. We appeal for further direct measurements of iodine species, laboratory experiments on the controlling factors, and multiscale simulations of iodine heterogeneous recycling.

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Observations of iodine oxide in the Indian Ocean marine boundary layer: A transect from the tropics to the high latitudes

Cited by 16 publications

References 60 publications

Estimation of Reactive Inorganic Iodine Fluxes in the Indian and Southern Ocean Marine Boundary Layer

Estimation of Reactive Inorganic Iodine Fluxes in the Indian and Southern Ocean Marine Boundary Layer

A review on air–sea exchange of reactive trace gases over the northern Indian Ocean

Role of Iodine Recycling on Sea‐Salt Aerosols in the Global Marine Boundary Layer

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