Early ship observational data and ICOADS

Many surface marine meteorological observations (similar to 125 million) from ships' logbooks have been assembled in the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) back to the late 18th century. We describe the makeup of the available data before 1950, and a recent update for that period incorporating a variety of US and international sources-focusing on the background, digitization, and processing of the US Maury Collection, which provides the earliest data ( mainly 1830-1860) currently blended into ICOADS. We also describe planned data and metadata additions to early ICOADS. Among these, the new Climatological Database for the World's Oceans (CLIWOC) will extend and enhance coverage for 1750-1854. Prospects for data improvements and homogeneity enhancements to further benefit climate research are also discussed.