An integrated database of ocean temperature and salinity observations

Observations made by surface-based instruments and subsurface profiling instruments have, up to now, largely been treated separately, motivated by a focus on different aspects of the climate system. However, activities such as coupled climate reanalyses, long-term forecasting, satellite validation, and climate monitoring increasingly want observations from both sets of instruments. To address this, we create an Integrated Ocean Database of global in situ temperature and salinity observations covering 1900-2010, which we name HadIOD. The database merges data taken from the latest versions of the International Comprehensive Ocean-Atmosphere Data Set (surface observations) and the Met Office Hadley Centre EN dataset (subsurface observations). Duplicates introduced by this process are flagged. In addition to the measurements and their basic metadata, each observation in the database is allocated a unique identifier, quality flags and, where possible, bias corrections and uncertainty estimates. A short investigation is presented demonstrating the use, and value, of some of the bias corrections and uncertainties in the database. While this paper describes our initial attempt at building HadIOD, there is much that could be done to build on the foundations presented here. Some ideas for future development are discussed.