The Met Office Hadley Centre's sea surface temperature data set, HadSST2, replaces the Met Office Historical Sea Surface Temperature dataset (MOHSST6) and is a monthly global field of SST (Sea Surface Temperature) on a 5 deg latitude by 5 deg longitude grid from 1850 to 2013. The data are neither interpolated nor variance adjusted.

The observations that make up this dataset are taken from the International Comprehensive Ocean-Atmosphere DataSet, ICOADS (see http://www.cdc.noaa.gov/coads/), until 1997 and from the NCEP GTS archive thereafter. Individual observations must first pass a series of quality checks (track check, reality check, positional check, climatology check, buddy check, duplicate check). The quality-checked observations in each 1degree longitude X 1degree latitude X pentad gridbox are then averaged using a winsorised average. The pentad climatology is then subtracted from these pentad superobs and the resulting anomalies are averaged to 5degree X 5degree X monthly resolution. The data are then bias-corrected for the use of buckets in the period 1850-1941.