Ambient air ozone mole fractions measured in the Swiss container during MOSAiC 2019/2020

This dataset contains minute-averaged ozone mole fractions measured during the year-long Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from October 2019 to September 2020. The measurements were performed in the Swiss container on the D-deck of Research Vessel Polarstern. Data were collected using a 2B Technologies instrument (model 205). The minute-averaged mole fractions were adjusted after cross-evaluation against measurements performed in the Atmospheric Radiation Measurement (ARM) Program container using a Thermo Fisher Scientific model 49i instrument. Negative spikes due to local anthropogenic pollution sources (e.g., exhaust by the vessel's engine and vents, skidoos, helicopters, on-ice diesel generators) were identified and flagged using the function “despike” from R package oce (version 1.3-0). Briefly, this function first linearly interpolates across any gaps (missing values). Then, it calculates a running median spanning k elements. The result of these two steps is the “reference” time-series. The standard deviation of the difference between values and the reference is then calculated. Values that differ from the reference by more than n times this standard deviation are considered to be spikes and eliminated. The function was applied twice with different k values (k = 1439 (1 day) and k = 61 (1 hour)) and n = 3. The data columns include the Date and Time in Coordinated Universal Time (UTC), the latitude and longitude of Research Vessel Polarstern, the MOSAiC event label, the original ozone mole fractions in nmol/mol, the adjusted ozone mole fractions in nmol/mol after cross-evaluation, and a pollution flag where 'yes' means that local pollution was detected.