Observational ozone datasets over the global oceans and polar regions (version 2024)

Kanaya, Yugo and Sommariva, Roberto and Saiz-Lopez, Alfonso and Mazzeo, Andrea and Koenig, Theodore K. and Kawana, Kaori and Johnson, James E. and Colomb, Aurélie and Tulet, Pierre and Molloy, Suzie and Galbally, Ian E. and Volkamer, Rainer and Mahajan, Anoop and Halfacre, John W. and Shepson, Paul B. and Schmale, Julia and Angot, Hélène and Blomquist, Byron and Shupe, Matthew D. and Helmig, Detlev and Gil, Junsu and Lee, Meehye and Coburn, Sean C. and Ortega, Ivan and Chen, Gao and Lee, James and Aikin, Kenneth C. and Parrish, David D. and Holloway, John S. and Ryerson, Thomas B. and Pollack, Ilana B. and Williams, Eric J. and Lerner, Brian M. and Weinheimer, Andrew J. and Campos, Teresa and Flocke, Frank M. and Spackman, J. Ryan and Bourgeois, Ilann and Peischl, Jeff and Thompson, Chelsea R. and Staebler, Ralf M. and Aliabadi, Amir A. and Gong, Wanmin and Malderen, Roeland Van and Thompson, Anne M. and Stauffer, Ryan M. and Kollonige, Debra E. and Martin, Juan Carlos Gómez and Fujiwara, Masatomo and Read, Katie and Rowlinson, Matthew and Sato, Keiichi and Kurokawa, Junichi and Iwamoto, Yoko and Taketani, Fumikazu and Takashima, Hisahiro and Navarro-Comas, Mónica and Panagi, Marios and Schultz, Martin G. (2025) Observational ozone datasets over the global oceans and polar regions (version 2024). Earth System Science Data, 17. pp. 4901-4932. ISSN 1866-3508

Abstract

Studying tropospheric ozone over the remote areas of the planet, such as the open oceans and the polar regions, is crucial to understand the role of ozone as a global climate forcer and regulator of atmospheric oxidative capacity. A focus on the pristine oceanic and polar regions complements the available land-based datasets and provides insights into key photochemical and depositional loss processes that control the concentrations and spatiotemporal variability in ozone as well as the physicochemical mechanisms driving these patterns. However, an assessment of the role of ozone over the oceanic and polar regions has been hampered by a lack of comprehensive observational datasets. Here, we present the first comprehensive collection of ozone data over the oceans and the polar regions. The overall dataset consists of 77 ship cruises/buoy-based observations and 48 aircraft-based campaigns. The dataset, consisting of more than 630 000 independent ozone measurement data points covering the period from 1977 to 2022 and an altitude range from the surface to 5000 m (with a focus on the lowest 2000 m), allows systematic analyses of the spatiotemporal distribution and long-term trends over the 11 defined ocean/polar regions. The datasets from ships, buoys, and aircraft are complemented by ozonesonde data from 29 launch sites or field campaigns and by 21 non-polar and 17 polar ground-based station datasets. The datasets contain information on how long the observed air masses were isolated from land, as estimated by backward trajectories from the individual observation points. To extract observations representative of oceanic conditions, we recommend using a subset of the data with an isolation time of 72 h or longer, from the analysis with coincident radon observations. These filtered oceanic and polar data showed typically flat diurnal cycles at high latitudes, whereas daytime decreases in ozone (11 %–16 %) were observed at lower latitudes. The ship/buoy- and aircraft-based datasets presented here will supplement the land-based ones in the TOAR-II (Tropospheric Ozone Assessment Report Phase II) database to provide a fully global assessment of tropospheric ozone. The described dataset is available at https://doi.org/10.17596/0004044 (Kanaya et al., 2025).