A Comparative Study of the Argo-Era Ocean Heat Content Among Four Different Types of Data Sets

Abstract

We conducted a comparative study of ocean heat content (OHC) in the top 2,000 m during the Argo-era using 12 latest and representative global ocean data sets. The differences in the global and basins-wide OHC trends were minor among the observation-based data sets, and remarkable among the ocean reanalyzes (RAs). Some RAs might exhibit much higher or lower basins-wide warming rates than the observation-based data sets. In the top 700 m, RAs suggested similar large-scale warming and cooling patterns, in agreement with the observation-based data sets. Below 700 m, the major warming and cooling features were significantly different between RAs and the observation-based data sets. All data sets suffered from relatively larger uncertainties in the highly dynamic regions. Special caution is suggested when estimating the OHC using only a single data set, especially a RA. Differences of RAs' OHC from observation-based data sets were significantly reduced when considering their ensemble mean, to be further confirmed with a larger sample of data sets.