'Improved analyses of changes and uncertainties in sea surface temperature measured in situ sice the midnineteenth century: The HadSST2 dataset' Journal of Climate, vol. 19, no. 3,
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Take down policyThe University of Edinburgh has made every reasonable effort to ensure that Edinburgh Research Explorer content complies with UK legislation. If you believe that the public display of this file breaches copyright please contact openaccess@ed.ac.uk providing details, and we will remove access to the work immediately and investigate your claim. (HadSST2)] is based on data contained within the recently created International Comprehensive OceanAtmosphere Data Set (ICOADS) database and so is superior in geographical coverage to previous datasets and has smaller uncertainties. Issues arising when analyzing a database of observations measured from very different platforms and drawn from many different countries with different measurement practices are introduced. Improved bias corrections are applied to the data to account for changes in measurement conditions through time. A detailed analysis of uncertainties in these corrections is included by exploring assumptions made in their construction and producing multiple versions using a Monte Carlo method. An assessment of total uncertainty in each gridded average is obtained by combining these bias-correctionrelated uncertainties with those arising from measurement errors and undersampling of intragrid box variability. These are calculated by partitioning the variance in grid box averages between real and spurious variability. From month to month in individual grid boxes, sampling uncertainties tend to be most important (except in certain regions), but on large-scale averages bias-correction uncertainties are more dominant owing to their correlation between grid boxes. Changes in large-scale SST through time are assessed by two methods. The linear warming between 1850 and 2004 was 0.52°Ϯ 0.19°C (95% confidence interval) for the globe, 0.59°Ϯ 0.20°C for the Northern Hemisphere, and 0.46°Ϯ 0.29°C for the Southern Hemisphere. Decadally filtered differences for these regions over this period were 0.67°Ϯ 0.04°C, 0.71°Ϯ 0.06°C, and 0.64°Ϯ 0.07°C.