Journal article Open Access
Willis, Josh K.; Lyman, John M.; Johnson, Gregory C.; Gilson, John
Two systematic biases have been discovered in the ocean temperature data used by Lyman et al. . These biases are both substantially larger than sampling errors estimated in Lyman et al. , and appear to be the cause of the rapid cooling reported in that work. Index Terms. 4513 Decadal ocean variability; 1225 Global change from geodesy; 4215 Climate and interannual variability; 4262 Ocean observing systems; 1635 Oceans Keywords. global warming; heat content; climate change Most of the rapid decrease in globally integrated upper (0–750 m) ocean heat content anomalies (OHCA) between 2003 and 2005 reported by Lyman et al.  appears to be an artifact resulting from the combination of two different instrument biases recently discovered in the in situ profile data. Although Lyman et al.  carefully estimated sampling errors, they did not investigate potential biases among different instrument types. One such bias has been identified in a subset of Argo float profiles. This error will ultimately be corrected. However, until corrections have been made these data can be easily excluded from OHCA estimates (see http://www.argo.ucsd.edu/ for more details). Another bias was caused by eXpendable BathyThermograph (XBT) data that are systematically warm compared to other instruments [Gouretski and Koltermann, 2007]. Both biases appear to have contributed equally to the spurious cooling. Acknowledgments. JML and GCJ were supported by the NOAA Climate Program Office and the NOAA Office of Oceanic and Atmospheric Research. The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the National Oceanic and Atmospheric Administration.