Measurements and modelling of i2, IO, OIO, BrO and NO 3 in the mid-latitude marine boundary layer

Saiz-Lopez, A, Shillito, J. A., Coe, H. and Plane, J. M. C. (2006) Measurements and modelling of i2, IO, OIO, BrO and NO 3 in the mid-latitude marine boundary layer. Atmospheric Chemistry and Physics, 6 (6). pp. 1513-1528.

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Abstract

Time series observations of molecular iodine (I2), iodine oxides (IO, OIO), bromine oxide (BrO), and the nitrate radical (NO3) in the mid-latitude coastal marine boundary layer (MBL) are reported. Measurements were made using a new long-path DOAS instrument during a summertime campaign at Mace Head on the B3Π(0+u)-X1Σ+g electronic transition between 535 and 575 nm. The I2 mixing ratio was found to vary from below the detection limit (~5 ppt) up to a nighttime maximum of 93 ppt. Along with I2, observations of IO, OIO and NO3 were also made during the night. Surprisingly, IO and OIO were detected at mixing ratios up to 2.5 and 10.8 ppt, respectively. A model is employed to show that the reaction between I2 and NO3 is the likely nighttime source of these radicals. The BrO mixing ratio varied from below the detection limit at night (~1 ppt) to a maximum of 6 ppt in the first hours after sunrise. A bromine chemistry model is used to simulate the diurnal behaviour of the BrO radical, demonstrating the importance of halogen recycling through sea-salt aerosol. In the same campaign a zenith sky DOAS was employed to determine the column density variation of NO3 as a function of solar zenith angle (SZA) during sunrise, from which vertical profiles of NO3 through the troposphere were obtained. On several occasions a positive gradient of NO3 was observed over the first 2 km, possibly due to dimethyl sulphide (DMS) removing NO3 at the ocean surface.

Item Type:	Article
Uncontrolled Keywords:	sdg 14 - life below water ,/dk/atira/pure/sustainabledevelopmentgoals/life_below_water
Faculty \ School:	Faculty of Science > School of Environmental Sciences
Depositing User:	Rosie Cullington
Date Deposited:	24 Jan 2011 15:04
Last Modified:	20 Mar 2024 10:31
URI:	https://ueaeprints.uea.ac.uk/id/eprint/19572
DOI:	10.5194/acp-6-1513-2006

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