This dataset, the International Comprehensive Ocean-Atmosphere Data Set (ICOADS), is the most widely-used freely available collection of surface marine observations, with over 455 million individual marine reports spanning 1662-2014-each containing the observations and metadata reported from a given ship, buoy, coastal platform, or oceanographic instrument, providing data for the construction of gridded analyses of sea surface temperature, estimates of air-sea interaction and other meteorological variables. ICOADS observations are assimilated into all major atmospheric, oceanic and coupled reanalyses, further widening its impact. R3, therefore includes changes designed to enable the effective exchange of information describing data quality between ICOADS, reanalysis centres, data set developers, scientists, and the public. These user-driven innovations include the assignment of a unique identifier (UID) to each marine report to enable tracing of observations, linking with reports and improved data sharing. Other revisions and extensions of the ICOADS' International Maritime Meteorological Archive (IMMA) common data format incorporate new near-surface oceanographic data elements and cloud parameters. Many new input data sources have been assembled, and updates and improvements to existing data sources, or removal of erroneous data, made. Additionally, these data are offered in NetCDF with useful metadata added in global and variable attributes of each file to make the NetCDF self-contained.

This dataset includes 2 versions of the official ICOADS Release 3 dataset: 1) the 'Total' product (denoted by 'T' in the filename) which contains all duplicates and is used for verification and research purposes; and 2) 'Final' R3, with duplicates removed, where all reports have been compared for matching dates, id's and elements observed and the best duplicate retained as the final report.