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Monday, October 4, 2010

October 2010 Update to NODC Ocean Heat Content Data

I’ve moved to WordPress.  This post can now be found at October 2010 Update to NODC Ocean Heat Content Data
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I was informed today (Thanks, Tim.) that the NODC has updated its GLOBAL OCEAN HEAT CONTENT data. This is the dataset based on the Levitus et al (2009) paper “Global ocean heat content(1955-2008) in light of recent instrumentation problems”, Geophysical Research Letters. Refer to Manuscript.

The NODC has provided a detailed explanation of ocean heat content (OHC) data changes. As soon as the update is made available through the KNMI Climate Explorer, I will provide an update to the individual ocean basin subsets, similar to January To March 2010 NODC Ocean Heat Content (0-700m) Update And Comments, and a quick look into the effects of the other changes. (KNMI updates the Climate Explorer toward the end of the month.)

The following gif animation is based on the graph currently displayed on the NODC’s GLOBAL OCEAN HEAT CONTENT webpage and one that was displayed there on June 24, 2010. There are two noticeable changes to the data over the last decade. The upward shift in 2003 has been decreased, and the data no longer declines since then. In fact, the dip in 2005 should produce a positive trend if one were to plot the annual data since 2003. And overall, the rise since the beginning of the dataset appears to have declined.

http://i54.tinypic.com/24178ur.jpg
Oct 2010 OHC Update

2 comments:

boballab said...

Watching that blink comparison, the Oct 4 graph looks like they smoothed the data. A lot of the jagged variation has been rounded off.

Dominic said...

Hi Bob
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From p11 of the NODC heat_content_differences.pdf, the first graph seems to show no trend 2003 - present for the NH OHC, while the SH chart might give an upward trend 2003 - present (eyeball).
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In general the recalculation seems to have lowered values for the SH more than the NH, especially since 2003.
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The conclusion makes this explicit (pdf p17):
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'Largest differences 2004-2008 in the Southern Hemisphere, where consistent data collection begins ~2004.
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Major factor in differences is new/changed data, updated quality control
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Questions to be answered: Are quality control differences related to Argo delayed-mode quality control, NODC handling of data, or both?'
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All very interesting. I look forward to more from NODC and from yourself once KNMI is updated.

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