We got big trouble in ocean heat content measurement. . . .
Ocean heat content measurements are proving to be especially troublesome. While the new ARGO float system holds the promise of improved data and is almost in place
problems have emerged with a large number of the floats, particularly in the North Atlantic that impose a cold bias on the measurements. This now appears to be understood and can be corrected for. That is the good news.
ARGO is a relatively young system with great promise. Deployment started in 2000 and has almost reached the 3000 float target. Each little bugger bobs up and down between the surface and 2000 m every 10 days measuring temperature, salinity and the flow of currents then phones home with the data
Expendable bathythermographs (XBT) are toss it over the side with a couple of wires that bring the data to the surface torpedo like gizmos that have been used since the 1950s. In Geophysical Research Letters, Gouretski and Kolterman argue that they have a warm bias of 0.2 - 0.4 K, and it may not be possible to correct the data which is a large part of the older measurements of oceanic temperature profiles.
This knocks a number of things into cocked hats. G&K estimate that
Using bias-corrected XBT data we argue reduces the ocean heat content change since the 1950s by a factor of 0.62. Our estimate of the ocean heat content increase (0–3000 m) between 1957–66 and 1987–96 is 12.8·1022 J. Because of imperfect sampling this estimate has an uncertainty of at least 8·1022 JThis leaves studies which relied on the XBT and ARGO data up an interesting river without a propulsion system. In particular, the Lyman, Willis and Johnson 2006 study which described a RecentCooling of the Upper Ocean, has a 2007 submitted correction that describes the effect of both problems. In short, the cooling described in the 2006 study is now seen to be an artifact.
Now, among the Friends of Rabett Run, ClimateScience has been the one most heavily invested in Lyman, Willis and Johnson, using it to argue strongly against the IPCC WG1 Summary for Policy Makers. To his credit Roger Sr., owner operator of Climate Science, noted the coming correction week or so ago. Eli commented
I would recommend caution with something like this. It is going to take a while for the calibration and other kinks in the ARGO float data to be worked out, and in the meantime there is great potential for egg on the face as was the case with the MSU fiasco’s. ARGO has the huge advantage that it was designed for the type of measurements that are being done. Moreover extrapolation with such a short data set is particularly risky given variability.The response was to attack the surface temperature record, via a 95 pager that apparently has been accepted by J. Geophys. Res. One wearies.