Dataset abstract The authors would highly appreciate to be contacted if the data is used for any purpose. We measured mixing ratios of CO, CO2 and CH4 with a PICARRO G2401 Gas Analyzer. Ozone (O3) mixing ratios were measured with a 2B Technology ozone monitor, model 205. We report five-minute averaged data cleaned from exhaust gas influence. Temporal coverage is from December 20, 2016 to April 10, 2017. The trace gas concentrations represent a large number of atmospheric processes that happen on different time scales. CO for example, has basically no sources other than combustion and can hence be used as tracer for air mass transport from regions with combustion activities (e.g., South Africa). CO has a lifetime of a few weeks. CO2 and CH4 are longer-lived trace gases which disperse globally. The data set shows that concentrations in the Northern Hemisphere are higher than in the Southern Hemisphere. Both trace gases are emitted by anthropogenic activities as well as natural sources. Over the cruise track, areas of the Southern Ocean were passed where these trace gases either outgas or are absorbed. Ozone is a secondary trace gas, meaning that it is formed in the atmosphere. It���s concentrations are relatively low. All trace gases data have been cleaned from exhaust gas influence. Dataset contents ACESPACE_trace_gas_concentration.csv, data file, comma-separated values data_file_header.txt, metadata, text README.txt, metadata, text change_log.txt, metadata, text NaN values denote missing values because of e.g., ship exhaust contamination or instrument maintenance. For latitude and longitude, NaN values are noted in cases where position data was not available for the given time period. Dataset license This trace as mixing ratio dataset from ACE is made available under the Creative Commons Attribution 4.0 International License (CC BY 4.0) whose full text can be found at https://creativecommons.org/licenses/by/4.0/ Change log v1.1 - data file updated - Ozone was corrected because a wrong calibration factor was applied in version 1.0 - CO2 and CH4 are now dry mixing ratios, the previous data were not corrected for water vapour - README updated accordingly with details of changes to processing - added change_log.txt file v1.0 - initial release of dataset

{"references": ["Schmale, J. et al. (2017) Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition. Sci. Data 4:170003 doi: 10.1038/sdata.2017.3", "Igor Pro. Version 6.37. WaveMetrics, Inc., Oregon, USA. https://www.wavemetrics.com/downloads/current/Igor%20Pro%206.3", "LabView. Martin Gysel-Beer. Paul Scherrer Institute, Switzerland.", "Schmale, J., Baccarini, A., Thurnherr, I., Henning, S., Efraim, A., Regayre, L., Bolas, C., Hartmann, M., Welti, A., Lehtipalo, K., Aemisegger, F., Tatzelt, C., Landwehr, S., Modini, R. L., Tummon, F., Johnson, J., Harris, N., Schnaiter, M., Toffoli, A., Derkani, M., Bukowiecki, N., Stratmann, F., Dommen, J., Baltensperger, U., Wernli, H., Rosenfeld, D., Gysel-Beer, M. and Carslaw, K. (2019). Overview of the Antarctic Circumnavigation Expedition: Study of Preindustrial-like Aerosols and Their Climate Effects (ACE-SPACE). Bulletin of the American Meteorological Society. https://doi.org/10.1175/BAMS-D-18-0187.1"]}

The Antarctic Circumnavigation Expedition was made possible by funding from the Swiss Polar Institute and Ferring Pharmaceuticals. We acknowledge the Swiss National Sciences Foundation grant no. 200021_169090 and the German Research Foundation (DFG) within SSP 1158 (Grant no. STR 453/12-1).