Extended Reconstructed Sea Surface Temperature (ERSST), Version 4

The Extended Reconstructed Sea Surface Temperature (ERSST) dataset is a global monthly sea surface temperature analysis on a 2x2 degree grid derived from the International Comprehensive Ocean-Atmosphere Dataset (ICOADS). The latest ERSST Version 4 (v4) is based on Version 3b (v3b). Major revisions for v4 include: updated and substantively more complete input data from the ICOADS Release 2.5 (R2.5); revised Empirical Orthogonal Teleconnections (EOTs) and EOT acceptance criterion; updated sea surface temperature (SST) quality control procedures; revised SST anomaly (SSTA) evaluation methods; updated bias adjustments of ship SSTs using Hadley Nighttime Marine Air Temperature version 2 (HadNMAT2); and a buoy SST bias adjustment not previously made in v3b. ERSST v4 is generated using in situ SST data and improved statistical methods that allow stable reconstruction when data are sparse. The monthly analysis extends from January 1854 to the present, but because of sparse data in the early years, there is damping of the analyzed signal before 1880. After 1880, the strength of the signal is more consistent over time. The product is updated monthly with the available GTS ship and buoy data for that month. Data for the time period from January 2001 to the previous month are recalculated every month. Data before January 2001 are not updated. Note that v3b data were recalculated every month for January 1985 to the previous month. The SST anomalies are computed with respect to a 1971-2000 month climatology. Local and short-term variations have been smoothed in the ERSST analysis. The product is suitable for long-term global and basin-wide SST studies, and it is used as an input to the NCEI Merged Land Ocean Surface Temperature (MLOST) product. The data are written to a monthly netCDF files with CF metadata attributes included.