A review of uncertainty in in situ measurements and data sets of sea-surface temperature

Contributors: John Kennedy, Elizabeth Kent

Based on Kennedy, J. J. (2014), A review of uncertainty in in situ measurements and data sets of sea surface temperature, Rev. Geophys., 52, 132, doi:10.1002/2013RG000434. A review can only provide a snapshot of the literature, but there is an advantage in having a review that is updated as the literature evolves. The text of this review is under version control and the files can be found on github. The review can be read as a regular web page using GitHub pages. As new papers and other resources become available, the text will be updated.

If you would like to contribute, write a new section, rewrite a section, propose a change to the structure, point out new papers, typos or anything else, then there are a number of ways this can be acheived. Set up a github account and raise an issue or fork the repository, or email me (John Kennedy).

Archives of in situ sea surface temperature (SST) measurements extend back more than 160 years. Quality of the measurements is variable, and the area of the oceans they sample is limited, especially early in the record and during the two world wars. Measurements of SST and the gridded data sets that are based on them are used in many applications so understanding and estimating the uncertainties are vital. The aim of this review is to give an overview of the various components that contribute to the overall uncertainty of SST measurements made in situ and of the data sets that are derived from them. In doing so, it also aims to identify current gaps in understanding. Uncertainties arise at the level of individual measurements with both systematic and random effects and, although these have been extensively studied, refinement of the error models continues. Recent improvements have been made in the understanding of the pervasive systematic errors that affect the assessment of long-term trends and variability. However, the adjustments applied to minimize these systematic errors are uncertain and these uncertainties are higher before the 1970s and particularly large in the period surrounding the Second World War owing to a lack of reliable metadata. The uncertainties associated with the choice of statistical methods used to create globally complete SST data sets have been explored using different analysis techniques, but they do not incorporate the latest understanding of measurement errors, and they want for a fair benchmark against which their skill can be objectively assessed. These problems can be addressed by the creation of new end-to-end SST analyses and by the recovery and digitization of data and metadata from ship log books and other contemporary literature.


1. Introduction
2. General classification of uncertainty
3. The Current State of Uncertainty in in situ SST Analyses
3.1 Defining sea-surface temperature
3.2 Individual Observational Errors
3.2.1 Random Measurement Errors
3.2.2 Random and Systematic Measurement Errors
3.2.3 Summary of Individual Observational Errors
3.3 Pervasive Systematic Errors and Biases
3.3.1 Bias Adjustments 1850 to 1941
3.3.2 Bias Adjustments 1941 to Present
3.3.3 Estimating Uncertainty in Bias Adjustments
3.3.4 Refinements to Estimates of Pervasive Systematic Errors
3.3.5 Assessing the Efficacy of Bias Adjustments
3.3.6 Summary of Pervasive Systematic Errors and Biases
3.4 Sampling Uncertainty
3.4.1 Grid-box Sampling Uncertainty
3.4.2 Large-scale Sampling Uncertainty
3.4.3 Summary of Sampling Uncertainty
3.5 Reconstruction Techniques and Other Structural Choices
3.5.1 Critique of Reconstruction Techniques
3.5.2 Other Structural Choices
3.5.3 Comparisons of Reconstructions
3.5.4 Summary of Reconstruction Techniques and Structural Uncertainty
3.6 Comparing Components of Uncertainty
3.7 Estimates of Total Uncertainty
4 Presentation of Uncertainty
5 Minimizing Exposure to Uncertainty
6 Satellites
7 Concluding Remarks and Future Directions