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HadCRUT4 ensemble member time series

Time series are presented as temperature anomalies (deg C) relative to 1961-1990. Each HadCRUT4 ensemble member time series is computed as grid box area weighted average of data filled grid boxes for the given ensemble member. To compensate for non-equal measurement coverage in the northern and southern hemispheres, global series are produced as an average of the northern and southern hemisphere averages, giving each hemisphere an equal weighting.

Uncertainties presented in the ensemble member time series files describe uncertainties in regional/global anomaly series arising from measurement and sampling uncertainty and from calculation of regional/global averages with incomplete regional/global measurement coverage. These additional uncertainties are identical for all ensemble members. Uncertainties arising from systematic biases are described by the set of 100 ensemble member time series, and so are not listed in these files.

The HadCRUT4 ensemble member time series files contain 6 columns:

Column 1 is the date.
Column 2 is the temperature anomaly time series for the ensemble member (deg C w.r.t. 1961-1990).
Column 3 is the 1 sigma uncertainty in the ensemble member's temperature anomaly time series described by the combination of measurement and sampling uncertainty and coverage uncertainty. This is the combination of uncertainty components listed in columns 4, 5 and 6.
Column 4 is the 1 sigma level of fully uncorrelated measurement and sampling uncertainty relating to uncorrelated uncertainties in land station records.
Column 5 is the 1 sigma level of partially correlated measurement and sampling uncertainty described by the HadCRUT4 error covariance matrices and relating to measurement and sampling uncertainties in sea-surface temperatures.
Column 6 is the 1 sigma level of uncertainty associated with limited global/regional coverage.

More details are given in the paper introducing the dataset.

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