GEOTRACES Intermediate Data Product 2021 version 2

The GEOTRACES Intermediate Data Product 2021 (IDP2021) is the third release of publicly available data products from the international GEOTRACES programme, and contains trace element and isotope (TEI) data reported before the end of 2020. The TEI data in the IDP2021 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at crossover stations. The IDP2021 represents a major new data release. Compared to IDP2017, IDP2021 improves data coverage significantly in all ocean basins, especially in the Arctic, the Indian Ocean and the Pacific. Overall, the new data product contains more than twice the number of cruises, stations and actual data values. IDP2021 also contains data for a large suite of biogeochemical parameters, as well as aerosol and rain data characterising atmospheric TEI sources and, for the first time, cryosphere TEI data from the Arctic. IDP2021 is comprised of five packages of digital data: (1) seawater discrete water sample data including TEIs as well as standard hydrographic parameters, (2) aerosol data, (3) precipitation data, (4) cryosphere data and (5) seawater sensor data. The digital data are available in ASCII, netCDF, and Ocean Data View collection formats, with data quality flags and 1-σ data error values where available. Metadata concerning data originators, analytical methods and original publications related to the data are linked in an easily accessible way. IDP2021 version 2 (IDP2021v2) includes additional data not available for version 1 and other amendments as detailed in the IDP2021v2 changes document. The GEOTRACES IDP2021 is released under the Creative Commons By Attribution (CC-BY) Licence 4.0 as described in the Fair Use Agreement.