I’ve moved to WordPress. This post can now be found at NODC Ocean Heat Content (0-700 Meters) – 2007, 2008 & 2009 Corrections##############
The National Oceanographic Data Center (NODC) recently updated its 4th quarter and annual 2009 Ocean Heat Content (OHC) data. The data that was presented in conjunction with the Levitus et al (2009) Paper now covers the period of 1955 to 2009. There have been changes that some might find significant.
This post presents:
1. A brief look at the revisions (corrections) to the data in 2007 and 2008 OHC data
2. A comparison of the NODC OHC data for the period of 2003 to 2009 versus the GISS projection
REVISIONS (Corrections) TO THE 2007 AND 2008 NODC OHC DATA
Figure 1 is a gif animation of two Ocean Heat Content graphs posted on the NODC GLOBAL OCEAN HEAT CONTENT webpage. It shows the differences between the current (January 2010) version and one that appears to include data through June or September 2009. So this is an “Official” correction (not more incompletely updated data posted on the NODC website discussed in NODC's CORRECTION TO OHC (0-700m) DATA, which required me to make corrections to a handful of posts). I have found nothing in the NODC OHC web pages that discuss these new corrections. Due to the years involved, is it safe to assume these are more corrections for ARGO biases? As of this writing, I have not gone through the individual ocean basins to determine if the corrections were to one ocean basin, a group of basins, or if they’re global; I’ll put aside the multipart post I’ve been working on for the past few weeks and try to take a look over the next few days.
NODC OHC OBSERVATIONS VERSUS GISS PROJECTION (2003-2009)
One of the posts that needed to be corrected back in October was NODC Ocean Heat Content (0-700 Meters) Versus GISS Projections (Corrected). The final graph in that post was a comparison of global ocean heat content observations for the period of 2003 through year-to-date 2009 versus the projection made by James Hansen of GISS of an approximate accumulation of 0.98*10^22 Joules per year. Figure 2 is an updated version of that comparison. Annual Global OHC data was downloaded from the NODC website (not through KNMI). The trend of the current version of the NODC OHC data is approximately 1.5% of the GISS projection. That is, GISS projected a significant rise, while the observations have flattened significantly in recent years. The apparent basis for the divergence between observations and the GISS Projection was discussed in the appropriately titled post Why Are OHC Observations (0-700m) Diverging From GISS Projections?
Note: The earlier version of that graph (with the NODC’s October 15, 2009 correction)…
…shows a linear trend of ~0.08*10^22 Joules/year. The current linear trend is ~0.015*10^22 Joules/year. Some might consider that decrease to be significant.
NOTE: I DELETED THE THIRD AND FOURTH PARTS OF THIS POST…
3. GLOBAL, HEMISPHERIC, AND INDIVIDUAL BASIN OHC UPDATE THROUGH DECEMBER 2009, AND
4. TREND COMPARISONS
…UNTIL I TRACK DOWN DISCREPANCIES I CAN’T EXPLAIN. I WILL REPOST THOSE SECTIONS IN A NEW POST. I BELIEVE I UNDERSTAND THE DIFFERENCES, BUT I NEED TO CHECK WITH KNMI.
NODC Annual Global OHC data used in Figure 2 is available here:
A quick read and eyeball would indicate that the North Atlantic OHC is the over-riding influence on GHC. Now at first this did surprise me somewhat but in reality perhaps not. Now here I will have to make quite a few unfounded assumptions so not clever but here goes.
The thermalhaline circulates the planet via the sth pacific, indian ocean then north to the artic while continuing round the cape.
The leg up the atlantic is necessarily slower than the main circulation and therefore has more time to absorb and emit heat to the surrounding ocean and atmosphere. Could this be the origin of its disproportionate influence. I know its not good science but ....
stephen richards: If we use THC as you did to refer to the global phenomenon, the North Atlantic also has Atlantic Meridional Overturning Circulation to vary it. It also gets the first impacts from El Nino events, with the only landmass between the tropical Pacific and the tropical and North Atlantic being a relatively "thin" Central America.
Global phenomenon yes but only that one can 'see' the AMO in all the Heat content graphs. Secondly, although the panama isthmus is vary thin i can't believe it passes much influence from the pacific and to my knowledge not influence shows up in the THC as it passes the isthmus. My thoughts were more along the lines of 2 streams merging in the sth atlantic one from the nth and one from the west with the one from the north influencing the one from the west as the northerly curren returns sth.
Something is missing here:
Sea level continues to rise at a rate of 3,3 mm/yr.
The Cazenave et al. 2008 paper "Sea level budget over 2003–2008: A reevaluation from GRACE space gravimetry,satellite altimetry and Argo" gives the following:
"we find a total ocean mass contribution of ∼2 mm/yr over 2003–2008".
So, let's calculate the termo-steric SLR rate:
Total SLR - Ocean mass SLR contribution = Thermo-steric SLR
(3,3 mm/yr)-(2 mm/yr)= 1,3 mm/yr
This is the thermo-steric SLR for 2003-2008 period.
For 1993-2003 period the thermo-steric SLR was 1,2 mm/yr, according to the J. I. Antonov, S. Levitus, and T. P. Boyer 2005 paper "Thermosteric sea level rise, 1955–2003".
So we have for thermo-steric SLR the following:
1993-2003: 1,2 mm/yr
2003-2008: 1,3 mm/yr
There is no sign of slowdown. The rates of SLR were almost equal.
Conclusion: the ocean still absorbs heat, with no sign of slowdown. If upper 700 m show no trend, then the heat must have been accumulated below.
Stephen mentioned that most heating occurred in North Atlantic. This probably is the "smoking gun" of AMOC(Atlantic Meridional Overturning Current) sequestering the heat in the Deep Ocean.
Regards and good luck with the troubled data,
From Lima, Peru
Stephen Richards: You wrote, “one can 'see' the AMO in all the Heat content graphs.”
Care to expand on that? Pick any one of my earlier OHC posts.
You wrote, “…although the panama isthmus is vary thin i can't believe it passes much influence from the pacific…”
My comment about the width of Central America was along the lines of how quickly changes in atmospheric circulation would be felt in the Gulf and North Atlantic, as opposed to the width of South America. The changes North Atlantic SST in response to ENSO events are caused by changes in atmospheric circulation--Walker Circulation, Hadley Circulation, etc. Here’s a link to Wang (2005), “ENSO, Atlantic Climate Variability, And The Walker And Hadley Circulation”:
Variations in SST are a portion of the variations in OHC. And many of the same factors that cause SST to vary also cause OHC to vary.
You wrote, “My thoughts were more along the lines of 2 streams merging in the sth atlantic one from the nth and one from the west with the one from the north influencing the one from the west as the northerly curren returns sth.”
You’ve confused me with that one. Here’s a map including names of currents. The names might help what you were trying to say.
Anonymous From Lima, Peru:
I’m not sure why you referenced Cazenave et al. 2008 and then went to the trouble of calculating the steric sea level rise from 2003-2008. Cazenave et al actually listed it, and their numbers are significantly different than yours.
In the conclusion (page 7) of Cazenave et al. 2008...
...they listed the steric sea level rise from 2003-2008 as being “on the order of 0.3 +/- 0.15mm/yr”. Then earlier they listed steric sea level for the period of 1993-2003 at 1.6 +/- 0.25 mm/yr. So according to Cazenave et al, steric sea level has flattened. Even compared to the Antonov et al 2005 value of 1.2 mm/yr you listed, the recent 0.3 mm/yr from Cazenave et al is still a significant slowdown.
You wrote, “Regards and good luck with the troubled data,”
It’s the only long-term OHC dataset that has been placed on the KNMI Climate Explorer, allowing the public to examine it. Also, the trouble appears during the ARGO period. Do these problems impact all of the ARGO-based papers that precede this discovery?
Cazenave used an OUDATED data of altimetric SLR: 2,5 mm/yr
Updated data show that after a 2007-2008 blip, the trend is near 3,3 mm/yr.
Good luck with the data!
From Lima, Peru
Stephen Richards: Also refer to:
The Tropical Atlantic shows respnses to La Nina events, as do the other tropical ocean datasets, and the high latitude variations are a function of the NAO.
Has anyone shown SLR is not LLS (Land Level Sinking)or SOD (satellite orbital decay)?
Anonymous (August 24, 2010 1:25 AM): I do believe both factors are accounted for, but do not know for sure.
Post a Comment