Size segregated aerosol samples were collected during the Very short lived bromine compounds in the ocean and their transport pathways into the stratosphere (TransBrom) cruise (FS Sonne, SO202) during 9 - 25 October 2009 in the western Pacific Ocean (~141 E - 146 E, 20 S – 43 N). The samples were collected by Christian Müller, Sebastian Wache and Arne Lanatowitz of GEOMAR, Kiel, Germany. The aerosol sampler was situated on the roof of the ship's wheelhouse. Samples were collected using a Sierra-type cascade impactor to separate the aerosol particles at an aerodynamic diameter cutoff of 1 µm. Collection time for the samples varied between 20.3 and 26.8 hours. Samples were extracted with ultrapure water and the major ions Na+, NH4+, Mg2+, K+, Ca2+, Cl-, NO3-, SO42-, oxalate, Br- and methanesulfonate were determined by ion chromatography (IC). Total soluble iodine (TSI) was determined by inductively coupled plasma - mass spectrometry (ICP-MS) and iodide (I-) and iodate (IO3-) were determined by IC-ICP-MS. The dataset contains the atmospheric concentrations of all measured soluble major ions (in nmol/m³) and iodine species (in pmol/m³).

Sampler Flow: 1 m³/minSubstrate Type: Whatman 41 celluloseSubstrate Pretreat: NoneSize Seg Method: Sierra type cascade impactor. Stages 3 and 4 were used and combined during analysis to give a fraction with aerodynamic diameter > 1 µm (Size_fraction 3-4). Backup filter collected the < 1µm fraction (Size_fraction w). Method Publication: Yodle and Baker, Atmospheric Environment X, 1, 100009, (2019). Baker et al., Deep-Sea Res., 54, 1704-1720, (2007).DL Value: Where the detection limit applies, concentrations are quoted as less than the limit of detection; Example atmospheric detection limits (given in Comment below) have been calculated from analytical detection limits for an air volume of 1400 m³.