>UPDATE (October 16,2009): This post contains erroneous OHC data posted at the NODC website. The post has been revised to reflect the corrections made by the NODC on October 15, 2009. Refer to “NODC Corrections to Ocean Heat Content (0-700m) Part 2“.
The first post in this series “ENSO Dominates NODC Ocean Heat Content (0-700 Meters) Data” illustrated the upward El Nino-induced step changes in the Ocean Heat Content (OHC) of the Tropical Pacific, Tropical Atlantic, South Pacific, South Indian, and South Atlantic datasets. The second post “North Atlantic Ocean Heat Content (0-700 Meters) Is Governed By Natural Variables” showed the impacts of the North Atlantic Oscillation (NAO) and ENSO on North Atlantic OHC. But the post the grabbed the most interest was the third in the series “Update of NODC (Levitus et al 2009) OHC Data Through June 2009”. It showed the drop of Global OHC over the past six months. Refer to Figure 1, which illustrates the monthly NODC Global OHC anomalies (0-700m) from January 1955 through June 2009.
In this post, I’ll clarify the source of the NODC data that I’ve used in this series of posts to counter the misdirection that is being presented in blogs, one in particular. And using an early 2009 post by Roger Pielke Sr. as reference, I’ll illustrate the growing difference between Global OHC and the projections of OHC made by GISS.
Members of NOAA’s National Oceanographic Data Center (NODC), S. Levitus, J. I. Antonov, T. P. Boyer, R. A. Locarnini, H. E. Garcia, and A. V. Mishonov, revised the NODC’s earlier OHC reconstruction and documented those changes in the paper “Global ocean heat content 1955–2008 in light of recently revealed instrumentation problems” GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L07608, doi:10.1029/2008GL037155, 2009. Link to paper:
A preprint version of the paper was available at the NODC website prior to publication through the NODC’s Global Ocean Heat Content webpage:
Through that same webpage, the NODC also made their OHC data available prior to the publication of Levitus et al (2009). I presented my first post on the new NODC OHC data on March 22, 2009 (The Latest Revisions to Ocean Heat Content Data), and, less than one month later, Geophysical Research Letters published Levitus et al (2009) on April 11, 2009. Since the publication of Levitus et al (2009), the NODC has updated its OHC data in the same way NCDC, Hadley Centre, and GISS update their global temperature anomaly data. The September 14, 2009 NODC OHC update included data for January through June 2009, but that update was only made available in global analyzed field format. The updated data files (22.4MB) are available in the following link:
And the instructions for the data:
Including the documentation:
The updated NODC OHC data is also available on a much more user-friendly basis through the Royal Netherlands Meteorological Institute (KNMI) Climate Explorer website:
As you’ll note, the NODC OHC data is one of many datasets that KNMI maintains and makes available to the public.
Open the Climate Explorer webpage. Scroll down and click on the “Heat content” “1955-now: NODC 0-700m” field for the NODC OHC data. Scroll back up, click on “Select Field”, enter the coordinates of the ocean area desired on the next webpage (-90, 90, -180, 180 for global data), hit “Enter”, and Climate Explorer provides graphs and links to raw data. Figure 2 is the NODC Global OHC anomaly graph created by Climate Explorer. Refer back in this thread to Figure 1. I created it with the raw NODC Global OHC data produced by Climate Explorer. My Figure 1 is a larger, easier-on-the-eyes version of the KNMI graph, Figure 2. Other than the presentation, there is no difference.
COMPARISON OF OHC DATA FROM THE NODC AND KNMI WEBPAGES
KNMI uses the 3-month-average OHC data available from the NODC website and lists those monthly averages for each month during the 3-month period. This “squares off” the monthly data. The anomaly data I’ve used in my earlier posts is calculated against the KNMI default base years of 1971-2000. KNMI presents the data in Gigajoules/sq meter (GJ/m^2). This allows users to define ocean coordinates for study and to compare multiple datasets without having to account for surface area. If the user then wants the data in another format such as 10^22 Joules used in climate studies, it would be up to the user to determine the correct surface area.
To simplify the comparison of the raw OHC data from the NODC website…
…and the same data through the KNMI Climate Explorer, I’ll use the annual average of the raw Global OHC data from KNMI (not anomalies). As noted above, the NODC presents its data in terms of 10^22 Joules, while KNMI provides the OHC data in GJ/m^2. The global ocean surface area listed in Wikipedia is 361 million sq km. If that surface area is used as a multiplier for the KNMI data, it proves to be too high, but as illustrated in Figure 3, 350 million sq km for the global ocean surface area provides a reasonable match.
You’ll also note that I’ve included the average of the January through June 2009 OHC data in the comparison. The drop over the first six months of 2009 was substantial.
COMPARISON OF OBSERVATION AND GISS PROJECTIONS
In a February 9, 2009 post titled ‘Update On A Comparison Of Upper Ocean Heat Content Changes With The GISS Model Predictions’, Roger Pielke Sr., provided a comparison of actual global ocean heat accumulation from 2003 through 2008 to those projected by the IPCC and GISS. So let’s list the annual NODC global OHC for the years 2003 through 2008 in the same format as Roger Pielke Sr’s post. Here’s another link to the NODC annual global data. Refer to the second column:
NODC GLOBAL OHC THROUGH NODC WEBSITE
2003 ~10.481*10**22 Joules
2004 ~12.154*10**22 Joules
2005 ~11.247*10**22 Joules
2006 ~12.211*10**22 Joules
2007 ~11.520*10**22 Joules
2008 ~12.339*10**22 Joules
And for comparison purposes, here are the KNMI-based NODC OHC values (using 350 million sq km as the global ocean surface area) used to create the comparison graph in Figure 3.
NODC GLOBAL OHC THROUGH KNMI WEBSITE (WITH JAN to JUN 2009 AVERAGE)
2003 ~10.532*10**22 Joules
2004 ~12.207*10**22 Joules
2005 ~11.276*10**22 Joules
2006 ~12.294*10**22 Joules
2007 ~11.640*10**22 Joules
2008 ~12.446*10**22 Joules
2009 ~9.692*10**22 Joules (Average of Jan through Jun 2009)
Roger Pielke Sr’s post refers to a communication from Jim Hansen of GISS in which Mr. Hansen wrote with the results of GISS model predictions. The post shows a GISS projected accumulation of 0.98*10**22 Joules per year. Using the 2003 value from the NODC Global OHC data (version through the KNMI website) as the base, the following table lists the annual GISS projected values for 2003 through 2009.
GISS PROJECTED GLOBAL OCEAN HEAT ACCUMULATION
2003 ~10.532*10**22 Joules
2004 ~11.512*10**22 Joules
2005 ~12.492*10**22 Joules
2006 ~13.472*10**22 Joules
2007 ~14.452*10**22 Joules
2008 ~15.432*10**22 Joules
2009 ~16.412*10**22 Joules
Global OHC could rebound over the second half of 2009, or it could drop more, or could remain near the value for the first half of the year. Let’s assume for the sake of example that the average of the first half of the year serves as an initial projection of the annual 2009 OHC value. Figure 4 compares the global OHC observations and GISS projections from 2003 to 2009. The divergence between the two is substantial.