DOI: 10.5281/zenodo.5176217
title: Concentration of gaseous iodic acid measured over the Southern Ocean in the austral summer of 2016/2017, during the Antarctic Circumnavigation Expedition (ACE).

description: Measurements of iodic acid concentration in the gas phase obtained with a nitrate chemical ionization mass spectrometer (we used an APi-TOF mass spectrometer produced by Tofwerk AG coupled with a Chemical ionization inlet A70 produced by Airmodus). Iodic acid is detected in the mass spectrometer either as a deprotonated ion or as a cluster with the reagent ion (NO3-). The concentration is calculated as the area of these two peaks normalized to the concentration of the reagent ions (monomer, dimer and trimer) and multiplied by a calibration factor equal to 6.9E9 molecules cm<sup>-3</sup> that was experimentally derived at Paul Scherrer Institute in the summer 2017, after the campaign. Iodic acid can participate in both new particle formation and growth, affecting the Earth radiative balance and cloud properties. Iodic acid is produced from the iodine radical but the exact formation pathways is still unknown. Measurements were performed on the upper deck of the icebreaker Akademik Tryoshnikov along the track of the Antarctic Circumnavigation expedition. Temporal coverage is from January 22, 2017 to March 19, 2017. There are no data for the first leg of the expedition because the instrument was not on the ship. The instrument was operated during leg 4 but data has not been processed yet. Data were collected with one-second time resolution but integrated to five minutes to increase the signal to noise ratio. Concentrations are reported as molecules per cubic centimeter in five minutes averages. The lower limit of detection was estimated to be lower than 6E3 molecules cm<sup>-3</sup>. Data below the detection limit were replaced by the detection limit divided by the square root of 2. Pollution from the ship exhaust and other human activities (e.g. helicopter flights) was identified as described in Schmale et al. 2019 (https://doi.org/10.1175/BAMS-D-18-0187.1) and a corresponding flag was associated to the data (with 1 meaning clean data and 2 polluted data). No direct influence of pollution on the iodic acid concentration was found. ***** Dataset contents ***** - 01_gas_iodic_acid_concentration_data.csv, data file, comma-separated values - 02_IodicAcid_file_header.txt, metadata, text format - 03_README.txt, metadata, text format
description: The Antarctic Circumnavigation Expedition was made possible by funding from the Swiss Polar Institute and Ferring Pharmaceuticals.
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