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 August 2013. The data are neither interpolated nor variance adjusted.

The SST data are taken from the International Comprehensive Ocean-Atmosphere Data Set, ICOADS, from 1850 to 1997 and from the NCEP-GTS from 1998 to the present. HadSST2 is produced by taking in-situ measurements of SST from ships and buoys, rejecting measurements which which fail quality checks, converting the measurements to anomalies by subtracting climatological values from the measurements, and calculating a robust average of the resulting anomalies on a 5° by 5° degree monthly grid. After gridding the anomalies, bias corrections are applied to remove spurious trends caused by changes in SST measuring practices before 1942. The uncertainties due to under-sampling have been calculated for the gridded monthly data as have the uncertainties on the bias corrections.

This dataset include:

- SST anomaly data (HadSST2_SST_1850on.txt.gz)

- 1961-1990 Climatology (HadSST2_climatology_5x5_1961_1990.txt)

- numbers of observations used to calculate the average (HadSST2_nobs_1850on.txt.gz)

- Estimates on the measurement and sampling errors on the SST data (HadSST2_m_and_s_errors_1850on.txt.gz)

- bias-adjusted data using bias adjustments which represent the 97.5 percent and 2.5 percent confidence levels of the estimated errors on the adjustments (HadSST2_97.5_pct_bias_1850on.txt.gz and HadSST2_2.5_pct_bias_1850on.txt.gz).

- Files showing the correction applied to the data e.g.:

HadSST2_bucket_correction_median.txt.gz - the corrections applied to the data 1850-1941

HadSST2_bucket_correction_2.5pc.txt.gz - the lower bound of the 95% confidence range of the uncertainties 1850-1941

HadSST2_bucket_correction_97.5pc.txt.gz - the upper bound of the 95% confidence range of the uncertainties 1850-1941

A 1 degree version of HadSST2 is also available.

Data were provided by the Met Office Hadley Centre. Dataset was produced by the Hadley Centre in collaboration with ICOADS.