Guest post by Bob Tisdale
SAME INTRODUCTION AS ALWAYS
The National Oceanographic Data Center’s (NODC) Ocean Heat Content (OHC) anomaly data for the depths of 0-700 meters are available through the KNMI Climate Explorer Monthly observations webpage. The NODC OHC dataset is based on the Levitus et al (2009) paper “Global ocean heat content (1955-2008) in light of recent instrumentation problems”. Refer to Manuscript. It was revised in 2010 as noted in the October 18, 2010 post Update And Changes To NODC Ocean Heat Content Data. As described in the NODC’s explanation of ocean heat content (OHC) data changes, the changes result from “data additions and data quality control,” from a switch in base climatology, and from revised Expendable Bathythermograph (XBT) bias calculations.
The NODC provides its OHC anomaly data on a quarterly basis. At the NODC website it is available globally and for the ocean basins in terms of 10^22 Joules. The KNMI Climate Explorer presents the quarterly data on a monthly basis. That is, the value for a quarter is provided for each of the three months that make up the quarter, which is why the data in the following graphs appear to have quarterly steps. Furnishing the OHC data in a monthly format allows comparisons to monthly datasets. The data is also provided on a Gigajoules per square meter (GJ/m^2) basis through the KNMI Climate Explorer, which allows for direct comparisons of ocean basins, for example, without having to account for surface area.
This update includes the data through the quarter of October to December 2011.
Let’s start the post with a couple of looks at the ARGO-era OHC anomalies.
ARGO-ERA OCEAN HEAT CONTENT MODEL-DATA COMPARISON
I’ve started the post with a graph that gets people riled up for some reason.
Figure 1 compares the ARGO-era Ocean Heat Content observations to an extension of the linear trend of the climate models presented in Hansen et al (2005) for the period of 1993 to 2003. Over that period, the modeled OHC rose at 0.6 watt-years per year. I’ve converted the watt-years to Gigajoules using the conversion factor readily available through Google: 1 watt years = 31,556,926 joules. Even with the recent uptick in Global Ocean Heat Content anomalies, the trend of the GISS projection is still 3.5 times higher than the observed trend.

Figure 1
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