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Thursday, February 25, 2010


I’ve moved to WordPress.  This post can now be found at WHEN DID GISS ADD ERSST.v3b DATA TO THEIR MAP-MAKING WEB PAGE?
UPDATE (March 31, 2010): Also refer to the post GISS Acknowledges Addition of ERSST.v3b Data To Their GISTEMP “Options”


Like many people, as soon as one of the climate change blogs (most often Lucia's The Blackboard) announces that GISS has posted their monthly GISTEMP global temperature anomalies, I visit the GISS Global Maps webpage to pull up the most recent map. I had stopped by the webpage a few times last week to look at maps of SST anomaly trends for a specific time periods, and there wasn’t anything out of the norm. But early this week I discovered that GISS has added another choice to the Ocean Data Source drop-down menu. Refer to Figure 1. They’ve added “NOAA/ER_v3b”. I don’t remember the option last week, and I don’t believe I would have overlooked it. Did they add it when they updated with their January 2010 data?
Figure 1

GISS uses HADISST SST data from January 1880 to November 1981 and then splices the NCDC’s OI.v2 SST data to it for the period after December 1981. That raises the question, Is GISS Changing SST Datasets? I found no mention of it on the GISS update page. There was no mention of it on GISTEMP homepage or the current analysis page. So the answer to that question is, dunno.

But if they weren’t planning to change SST datasets, why add the ERSST.v3b SST anomaly data to the webpage? I’m not going to speculate on all of the possible reasons for adding the ERSST.v3b SST data to the map-making page, but the only thing that makes sense to me is that they’re planning to switch datasets.

A better question, why would GISS change SST datasets? The OI.v2 SST data from the NCDC, presently being used by GISS after December 1981, is satellite based and is said to have a cool bias when compared to data based on ship and buoy readings. Figure 2 compares global SST anomalies for the ERSST.v3b and OI.v2 SST datasets from January 1982 to December 2009. The linear trend for the OI.v2 SST anomaly data is 0.095 deg C/decade, while the ERSST.v3b data shows a linear trend of 0.11 deg C/decade. If they change to the ERSST.v3b data, they’d add to the linear trend of the SST data. Global temperatures would rise even more.
Figure 2

Note: Recall that the original version of ERSST.v3 SST data included the satellite-based data, and that the NCDC went to great lengths to include that satellite data. In fact, a good portion of Smith et al (2008) Improvements to NOAA's Historical Merged Land-Ocean Surface Temperature Analysis (1880-2006), dealt with the benefits of the satellite data. But the satellite data was deleted due the cold bias. The NCDC wrote in explanation in a November 14, 2008 attachment to their main ERSST.v3b webpage, “In the ERSST version 3 on this web page WE HAVE REMOVED SATELLITE DATA from ERSST and the merged product. The addition of satellite data caused problems for many of our users. Although, the satellite data were corrected with respect to the in situ data as described in reprint, there was a residual cold bias that remained as shown in Figure 4 there. The bias was strongest in the middle and high latitude Southern Hemisphere where in situ data are sparse. THE RESIDAL BIAS LED TO A MODEST DECREASE IN THE GLOBAL WARMING TREND AND MODIFIED GLOBAL ANNUAL TEMPERATURE RANKINGS.” [Caps added.] The link for that quote is here:

If we look at the pre-satellite data (January 1880 to December 1981), Figure 3, the linear trends of the HADISST (presently used by GISS) and the ERSST.v3b data are basically the same, at approximately 0.03 deg C/decade, or 0.3 deg C per century.
Figure 3

Note, however, prior to 1940, the variations in the ERSST.v3b SST anomaly data are much greater than the HADISST data. So alarmists who wanted to take advantage of that fact would begin their trend analysis at the commonly used start of the 20th Century. See Figure 4. The ERSST.v3b data would add about another 0.12 deg C/century.
Figure 4

The ERSST.v3b data would have some disadvantages for alarmists. The dip and rebound from the late 19th to the early 20th centuries is much greater with the ERSST.v3b data. As shown in Figure 5, there was little difference between the SST anomalies in the early 1880s and those in the 1970s.
Figure 5

The dip and rebound in the HADISST data presently used by GISS is not as significant. Refer to Figure 6.
Figure 6

In short, GISS would have to increase the effects of volcanic aerosols in their Model E to account for the greater variability of the ERSST.v3b SST data prior to 1940.

The presentation of ocean coverage for the two datasets is similar. This can be seen in the two linear trend maps created via the GISS map-making webpage, Figures 7 and 8. Though it’s not visible in those maps, for the pre-satellite period, the HADISST data is presented in 1 deg latitude and longitude grids, while the ERSST.v3b data is in 2 deg grids. For the satellite era, in areas with sea ice and in other locations where ship and buoy readings are sparse, the OI.v2 data has better coverage than the ERSST.v3b data.
Figure 7
Figure 8

Every time I see a map of SST anomalies, or long-term trends in SST anomalies, I remind myself that much of the data is infilled by the Hadley Centre and NCDC. Long-term SST data from the Hadley Centre and NCDC is based on COADS data. And as illustrated with the maps of typical (boreal winter) monthly (January) SST anomalies for 1910, 1930, 1950, and 1970, Figure 9, the coverage prior to the satellite era was poor and in many areas non-existent. In January 1910, the vast majority of the Pacific and all oceans south of the equator were unsampled. In time, coverage improved, but was pretty much limited to shipping lanes. As recent as January 1970, there are still very few readings south of 45S and for a good portion of the Southeast South Pacific.
Figure 9

Comparing the Global temperature anomalies for GISTEMP based on the ERSST.v3b SST data (Figure 10) and the present merged HADISST/OI.v2 data (Figure11), if GISS were to change SST datasets, the January 2010 Global Surface Temperature anomaly would rise 0.03 deg C.
Figure 10
Figure 11

And the rise in Global Surface Temperatures based on the linear trends from 1900 to 2009 would increase 0.1 deg C. Refer to Figures 12 and 13.
Figure 12
Figure 13

Is GISS planning to switch SST datasets? I see no other reason for including the ERSST.v3b data in GISS map-making webpage. The switch would increase temperature trends but it would do so based only on the different methods used to reconstruct and measure the sea surface temperatures of the global oceans.

Note that the highest global ERSST.v3b SST anomaly at the peak of the 1997/98 El Nino is ~0.52 deg C in Figure 5, but is ~0.25 deg C in Figure 2. This is, of course, a result of the different base years used for the anomalies. The default base years used by the KNMI Climate Explorer are 1971 to 2000. If the period selected does not cover all of the years of the default base period, another period is used.

Note also, on the map of the ERSST.v3b data, Figure 8, some of the areas with the highest trends are the areas with the poorest coverage in the early decades. That will be the basis for a future post.

ERSST.v3b, HADISST, OI.v2 SST and COADS data are available through the KNMI Climate Explorer:

Monday, February 22, 2010

Mid-February 2010 SST Anomaly Update

I’ve moved to WordPress.  This post can now be found at Mid-February 2010 SST Anomaly Update
Not much to report.

Weekly NINO3.4 SST anomalies for the week centered on February 17, 2010 show that central equatorial Pacific SST anomalies have leveled off for the past few weeks. Presently they’re at 1.21 deg C.
NINO3.4 SST Anomalies

Refer also to Australia’s Bureau of Meteorology ENSO Wrap-Up webpage for other indicators:

Weekly Global SST anomalies are still elevated. While they are lower than the peak this ENSO season, the Global SST anomalies appear content to cycle where they are now. There’s still no indication that there will be a lagged rise, but they also not dropping very quickly.
Global SST Anomalies


OI.v2 SST anomaly data is available through the NOAA NOMADS system:

Saturday, February 13, 2010

La Nina - The Underappreciated Portion Of ENSO

I’ve moved to WordPress.  This post can now be found at La Nina – The Underappreciated Portion Of ENSO
Perform a Google Scholar search for documents including “El Nino” in quotes and there will be more than 200,000 results. On the other hand, “La Nina” will only raise 26,000+. Granted, the formal name of the coupled ocean-atmosphere phenomenon in the tropical Pacific is “El Nino-Southern Oscillation”, but that in quotes only returns 28,000+ results. So it appears that El Nino events do get much more “press” from the scientific community than La Nina events.

Figure 1 is a time-series graph of NINO3.4 SST anomalies from January 1979 to January 2010. El Nino events are a warming of the central and eastern tropical Pacific so they are displayed as a Positive SST anomaly, where La Nina events are a Negative. Visually, is the eye drawn to the upward spikes more than it is to the downward troughs? El Nino events are viewed as being larger in magnitude than La Nina events. NINO3.4 SST anomalies peaked at approximately 2.8 deg C during the Super El Nino events of 1982/83 and 1997/98, while the La Nina events that followed them failed to reach -2 deg C. But the La Nina events of 1988/89 and 2007/08 were stronger than the El Nino events that preceded them. (Refer to the note about base years at the end of this post.)

Figure 1

El Nino events release heat from the tropical Pacific, and through ocean currents and changes in atmospheric circulation, they raise surface temperatures outside of the tropical Pacific. These upward spikes in global temperatures, Figure 2, call attention to El Nino events during periods when global temperatures are rising. During La Nina events, the tropical Pacific releases less heat than normal, and global temperatures decline, which doesn’t have the same visual impact.
Figure 2

La Nina events are a vital portion of the El Nino-Southern Oscillation coupled ocean-atmosphere process. La Nina events recharge the heat released from the tropical Pacific during the El Nino. Figure 3 is a graph of Tropical Pacific Ocean Heat Content compared to scaled NINO3.4 SST anomalies. Note that most La Nina events do not fully recharge the heat released by the El Nino events. From 1976 to 1994, tropical Pacific Ocean Heat Content dropped almost continuously, with occasional major dips and rebounds as an El Nino discharged heat and the subsequent La Nina partially recharged it. Then, the 1995/96 La Nina event, one that was not particularly strong, replaced all of the heat that had been released (plus some) over that 18-year stretch.
Figure 3

During a La Nina event, tropical Pacific trade winds rise above normal levels. The increase in trade winds reduces cloud cover. Reduced cloud cover allows more Downward Shortwave Radiation (visible light) to warm the tropical Pacific. These coupled ocean-atmosphere processes associated with La Nina events were discussed in the post More Detail On The Multiyear Aftereffects Of ENSO - Part 2 – La Nina Events Recharge The Heat Released By El Nino Events AND...During Major Traditional ENSO Events, Warm Water Is Redistributed Via Ocean Currents”.

As noted above, the 1995/96 La Nina was not a strong event, yet it recharged all of the ocean heat that had been released in almost two decades of El Nino events. In “Genesis and Evolution of the 1997-98 El Niño” [ Science 12 February 1999: Vol. 283. no. 5404, pp. 950 – 954, DOI:10.1126/science.283.5404.950], Michael McPhaden explains, “For at least a year before the onset of the 1997–98 El Niño, there was a buildup of heat content in the western equatorial Pacific due to stronger than normal trade winds associated with a weak La Niña in 1995–96.” Link to Science abstract:

Link to NOAA copy of McPhaden (1999):

So there was a short-term recharge of tropical Pacific Ocean Heat Content in 1995/96, which is very evident in Figure 3. And this short-term buildup of heat content provided the fuel for the 1997/98 El Nino. Contrary to the beliefs of anthropogenic warming proponents the 1997/98 El Nino was NOT fueled by a long-term accumulation of heat from manmade greenhouse gases.

The 1997/98 El Nino was strong enough to temporarily raise Global Lower Troposphere Temperature anomalies ~0.7 deg C, as illustrated in Figure 4. Note: The period of 1995 to present was used in the following graphs because there have been no explosive volcanic eruptions since 1995 to add unwanted noise to the data.
Figure 4

And referring to Figure 5, Lower Troposphere Temperature anomalies of the Mid-To-High Latitudes of the Northern Hemisphere rose, but remained at elevated levels that varied well above the value in late 1996. This upward step (and a similar but smaller one caused by the 1986/87/88 El Nino) was discussed in the post “RSS MSU TLT Time-Latitude Plots...Show Climate Responses That Cannot Be Easily Illustrated With Time-Series Graphs Alone”.
Figure 5

Sea Surface Temperature anomalies for the Mid-To-High Latitudes of the Northern Hemisphere also rose and remained at an elevated level. Refer to Figure 6, which compares that dataset to scaled NINO3.4 SST anomalies. The latitudes used for the SST anomalies in this illustration are 20N-65N, which are latitudes that have little impact from polar ice. This upward step in the Sea Surface Temperature anomalies for the Mid-To-High Latitudes of the Northern Hemisphere will be discussed in a future post. I have, however, discussed the impacts of El Nino events on the North Atlantic in the post There Are Also El Nino-Induced Step Changes In The North Atlantic. And the North Atlantic is also impacted by the Atlantic Multidecadal Oscillation, but that appears to have peaked in 2005.
Figure 6

And for those wondering how well the SST and TLT anomalies for the Mid-To-High Latitudes of the Northern Hemisphere correlate, I’ve prepared Figure 7. The SST anomaly data were scaled by a factor of 1.8. There are divergences from year to year, but keep in mind that the coverage areas are very different; the TLT anomalies also include data over continental land masses. One thing is certain; the 1997/98 El Nino caused upward steps in both datasets.
Figure 7

And there are the impacts of the 1997/98 El Nino on the East Indian and West Pacific Oceans (60S-65N, 80E-180), which I first discussed in a series of posts more than a year ago. The 1997/98 El Nino shifted Sea Surface Temperature anomalies upward in this area of the global oceans, too. Refer to Figure 8. The cause of this was discussed in the posts Can El Nino Events Explain All of the Global Warming Since 1976? – Part 1 and Can El Nino Events Explain All of the Global Warming Since 1976? – Part 2.
Figure 8

Basically, the warm water that was built up during the 1995/96 La Nina collected below the surface of an area in the western tropical Pacific known as the Western Pacific Warm Pool (to depths of 300 meters). During the 1997/98 El Nino, the warm water contained in the Western Pacific Warm Pool sloshed east and spread across the surface of the central and eastern tropical Pacific. The warmer-than-normal waters raised Sea Surface Temperatures and changed atmospheric circulation. Then, as the La Nina of 1998/99/00/01 progressed, the trade winds, Pacific Equatorial Currents, and a phenomenon known as a Rossby wave returned the remaining surface and subsurface warm water to the western Pacific. Some of the warm water returned to the Pacific Warm Pool, but a major portion of it remained on the surface and was redistributed by ocean currents to western North and South Pacific, and a portion of the warm water migrated to the Eastern Indian Ocean.

So, if you’re wondering why the present moderate El Nino event of 2009/10 is raising global temperatures to record levels, you have to go back in time. The 1995/96 La Nina provided the build-up of warm waters that was then discharged by the 1997/98 El Nino and redistributed by the 1998/99/00/01 La Nina. The end results were upward steps in SST anomalies and TLT anomalies for major portions of the globe.

One of the methods anthropogenic global warming advocates (scientists and bloggers) use to illustrate the assumed effects of greenhouse gases on global temperatures is to illustrate the divergence between the linear trends of global temperatures and a scaled ENSO index such as NINO3.4 SST anomalies. Refer to Figures 9 and 10. But the upward steps illustrated in Figure 5 and 6 bias global temperature data upwards.
Figure 9
Figure 10

And the biases created by those step changes in the SST and TLT anomalies of the Mid-To-High Latitudes of Northern Hemisphere are responsible for much of the differences between NINO3.4 SST anomalies and global temperature anomalies. We can illustrate this looking at the data for the rest of the world; that is, by comparing the linear trend of NINO3.4 SST anomalies with the linear trends the TLT and SST anomalies for the tropics and the Mid-To-High Latitudes of the Southern Hemisphere. Refer to Figures 11 and 12. As shown, the linear trends of the NINO3.4 SST anomalies are slightly negative, but the linear trends for the SST and TLT anomalies of the tropics and Mid-To-High Latitudes of the Southern Hemisphere are relatively flat--much flatter than the global datasets.
Figure 11
Figure 12

That would mean the ENSO-induced step increases in SST and TLT anomalies of the Mid-To-High Latitudes of the Northern Hemisphere caused the vast majority of the positive linear trends for the global SST and TLT anomaly datasets. See Figures 13 and 14, which show the strengths of the positive trends for those areas of the globe.
Figure 13
Figure 14

Figures 15 and 16 compare the SST and TLT anomalies for the Mid-To-High Latitudes of the Northern Hemisphere to the Global data and to the SST and TLT anomalies for the Mid-To-High Latitudes of the Southern Hemisphere. It should now be clear that the majority of the rises in Global SST and TLT anomalies since 1995 were caused by the 1997/98 El Nino-induced upward steps in the SST and TLT anomalies for the Mid-To-High Latitudes of the Northern Hemisphere.
Figure 15
Figure 16

In short, the effects of the La Nina- and El Nino-induced step changes in the SST and TLT anomalies of Mid-To-High Latitudes of the Northern Hemisphere are mistaken for, and misrepresented as proof of, anthropogenic global warming.

The 1972/73 El Nino was a strong ENSO event. NINO3.4 SST anomalies, referring to Figure 17, peaked above 2 deg C. There were only two El Nino events stronger than the 1972/73 El Nino in the second half of the 20th Century, and they were the two Super El Nino events of 1982/83 and 1997/98.
Figure 17

But the 1972/73 El Nino shares another superlative with the 1997/98 El Nino. Both El Nino events were followed by La Nina events that lasted through not one ENSO season, not two ENSO seasons—they lasted through three consecutive ENSO seasons. The La Nina event of 1998/99/00/01 recharged the heat content released by the 1997/98 El Nino and returned the tropical Pacific Ocean Heat Content to the new higher levels established during the 1995/96 La Nina. Refer to Figure 18. The La Nina event of 1973/74/75/76 recharged the heat released from the Tropical Pacific by El Nino events during the decade of the early 1960s to the early 1970s. And it also added to the Tropical Pacific Ocean Heat Content.
Figure 18

The Pacific Climate Shift of 1976/77 is a much-studied phenomenon. Trenberth et al (2002) discussed the differences in the evolution of El Nino events before and after the shift, and Trenberth et al (2002) referenced other papers that discussed effects of the Pacific Climate Shift on ENSO. Link to Trenberth et al (2002):

El Nino events became stronger after the Pacific Climate Shift. The frequency of El Nino events and El Nino Modoki increased. As noted in an early post, The 1976 Pacific Climate Shift, there were notable shifts in the SST anomalies and linear trends of Pacific Ocean basin subsets.

But I have yet to find a paper that attributes the Pacific Climate Shift of 1976/77 to the La Nina event of 1973/74/75/76 or one that even suggests that the 3-year-long La Nina played a role. Yet through known coupled ocean-atmosphere processes, the 1973/74/75/76 La Nina increased the warm water available for the additional El Nino events after 1976 and for the significant El Nino events of 1982/83 and 1986/87/88.

The explosive volcanic eruption of El Chichon may have counteracted the Super El Nino of 1982/83, but the 1986/87/88 El Nino was strong enough to cause upward shifts in the SST and TLT anomalies of the Mid-To-High Latitudes of the Northern Hemisphere, and the SST anomalies of the East Indian and West Pacific Oceans, similar to the shifts caused by the 1997/98 El Nino illustrated in this post.

Note: The relative strengths of El Nino versus La Nina events discussed early in this post would of course depend on the base years chosen for anomalies. And as illustrated in Figure 17 there is a minor difference depending on whether the base years of 1950 to 1979 or 1979 to 2000 are used. The significance of the difference would depend on how the data is being used. Example: A scaled running total of NINO3.4 SST anomalies will reproduce the basic global temperature anomaly curve as illustrated in Reproducing Global Temperature Anomalies With Natural Forcings if the base years are 1950 to 1979. If the base years of 1979 to 2000 are used, the result will not be similar to the global temperature curve.
Figure 19

The La Nina event of 1973/74/75/76 provided the tropical Pacific Ocean Heat Content necessary for the increase in strength and frequency of El Nino events from 1976 to 1995. The 1995/96 La Nina furnished the Ocean Heat Content that served as fuel for the 1997/98 El Nino. And the 1998/99/00/01 La Nina recharged the tropical Pacific Ocean Heat Content after the 1997/98 El Nino, returning it to the new higher level established by the La Nina of 1995/96.

It would appear that La Nina events do all of the work, while El Nino events get all the glory—and the research.

All data for this post is available through the KNMI Climate Explorer:

Monday, February 8, 2010

January 2010 SST Anomaly Update

I’ve moved to WordPress.  This post can now be found at January 2010 SST Anomaly Update
UPDATE (3-8-10): Corrected South Atlantic graph.
Monthly NINO3.4 SST Anomalies Have Peaked. Have Global Temperature SST Anomalies?


The map of Global OI.v2 SST anomalies for January 2010 downloaded from the NOMADS website is shown below.

January 2010 SST Anomalies Map (Global SST Anomaly = +0.29 deg C)

Global SST anomalies dropped slightly (-0.021 deg C) between December and January. The rise in the Southern Hemisphere (+0.018 deg C) was overridden by the decrease in the Northern Hemisphere (-0.071 deg C). The equatorial Pacific remains in El Nino conditions (Monthly NINO3.4 SST Anomaly = +1.55 deg C and Weekly NINO3.4 SST Anomaly = +1.21 deg C). Monthly NINO3.4 SST anomalies dropped -0.27 in January, while the weekly data NINO3.4 SST anomalies have dropped (-0.73 deg C) from their peak over the past six weeks. NINO3.4 SST Anomalies appear to have reached their peak for the season.
Monthly Change = -0.021 deg C
NINO3.4 SST Anomaly
Monthly Change = -0.267 deg C


I’ve added the East Indian-West Pacific SST Anomaly data more than one year in advance of when any evidence of a step change would occur. (I’m trying to draw attention to the atypical response.) Using the 1986/87/88 and 1997/98 El Nino events as references, East Indian-West Pacific SST Anomalies peak about 7 to 9 months after the peak of the NINO3.4 SST anomalies, so we shouldn’t expect any visible sign of a step change for almost 18 to 24 months. We’ll just have to watch and see. I’ve also revised the blocked question in the illustration to include “& 2010/11 La Nina”, since the rise would actually occur during, and be caused in part by, the La Nina event.
East Indian-West Pacific (60S-65N, 80E-180)
Monthly Change = -0.058 deg C

Further information on the upward “step changes” that result from strong El Nino events, refer to my posts from a year ago Can El Nino Events Explain All of the Global Warming Since 1976? – Part 1 and Can El Nino Events Explain All of the Global Warming Since 1976? – Part 2

And for the discussions of the processes that cause the rise, refer to More Detail On The Multiyear Aftereffects Of ENSO - Part 2 – La Nina Events Recharge The Heat Released By El Nino Events AND...During Major Traditional ENSO Events, Warm Water Is Redistributed Via Ocean Currents -AND- More Detail On The Multiyear Aftereffects Of ENSO - Part 3 – East Indian & West Pacific Oceans Can Warm In Response To Both El Nino & La Nina Events


The MONTHLY graphs illustrate raw monthly OI.v2 SST anomaly data from November 1981 to January 2009.

Northern Hemisphere
Monthly Change = -0.071 deg C
Southern Hemisphere
Monthly Change = +0.018 deg C
North Atlantic (0 to 75N, 78W to 10E)
Monthly Change = -0.006 deg C
South Atlantic (0 to 60S, 70W to 20E)
Monthly Change = +0.202 deg C
North Pacific (0 to 65N, 100 to 270E, where 270E=90W)
Monthly Change = -0.093 Deg C
South Pacific (0 to 60S, 145 to 290E, where 290E=70W)
Monthly Change = -0.011 deg C
Indian Ocean (30N to 60S, 20 to 145E)
Monthly Change = +0.003 deg C
Arctic Ocean (65 to 90N)
Monthly Change = -0.032 deg C
Southern Ocean (60 to 90S)
Monthly Change = +0.038 deg C


The weekly NINO3.4 SST anomaly data illustrate OI.v2 data centered on Wednesdays. The latest weekly NINO3.4 SST anomalies are +1.21 deg C, down from a peak of 1.94 Deg C six weeks ago.
Weekly NINO3.4 (5S-5N, 170W-120W)

The Optimally Interpolated Sea Surface Temperature Data (OISST) are available through the NOAA National Operational Model Archive & Distribution System (NOMADS).

Friday, February 5, 2010

OHC Linear Trends and Recent Update of NODC OHC (0-700 Meters) Data

I’ve moved to WordPress.  This post can now be found at OHC Linear Trends and Recent Update of NODC OHC (0-700 Meters) Data
The National Oceanographic Data Center (NODC) presented its Ocean Heat Content (OHC) data in conjunction with the Levitus et al (2009) Paper. The NODC makes the data available to the public and maintains it at their GLOBAL OCEAN HEAT CONTENT webpage. About January 20, 2010, the NODC added its 4th quarter and annual 2009 OHC data so that it covered the period of 1955 to 2009. On January 29 and February 1, 2010, the NODC also updated its 2006-and-later data. The KNMI Climate Explorer was updated in response to the 4th quarter NODC OHC additions and, on February 1, to the 2006-and-later revisions. (Thanks to Tim and Geert Jan for the timely updates.)

This post presents:
1. A brief look at impact of the revisions (corrections) to the 2006-and-later OHC data
2. OHC Trend Comparisons for individual ocean basins and hemispheres
3. An update of the global, hemispheric, and basin OHC data through December 2009

A Note About The Data Presented In This Post: This data used in the graphs (except Figure 2) was downloaded through the KNMI Climate Explorer website, which allows users to define the coordinates of the desired data subset. The data is presented in Gigajoules per square meter (GJ/m^2), not in 10^22 Joules like the NODC. In the GJ/m^2 format, subsets are easier to compare, since adjustments for surface area do not have to be made (they’ve already been made). The NODC presents quarterly data. KNMI includes those quarterly values for each corresponding month. This “squares off” the monthly data in the graphs, since the one value is the same for three consecutive months, but it permits comparisons to other monthly datasets, such as NINO3.4 SST anomalies.

I provided a quick introduction to the revisions (corrections) to the 2006-and-later OHC data in my recent post NODC Ocean Heat Content (0-700 Meters) - 2007, 2008 & 2009 Corrections. In that post, I had not noticed that the 2006 data had also been revised.

Figure 1 is a time-series graph of the updated and revised Global OHC data. The cell in the upper right-hand corner shows an earlier version, before the revisions to the 2006-and-later data. I have found nothing in the NODC OHC web pages that discuss these new corrections. Are they more corrections for ARGO biases?
Figure 1

The revisions to the 2006-and-later data shown in Figure 1 had little impact on the overall rise in the data since 1955. To confirm this, as illustrated in Figure 4 of this post, the linear trend of the revised and updated data for January 1955 through December 2009 is 0.078 GJ/meter^2/ decade. Before the revisions to the 2006-and-later data, the linear trend for the same period (not shown) was 0.079 GJ/meter^2/ decade.

The revisions to the recent data do impact the trend of the short-term data used to illustrate the divergence between the observations and the GISS projections. This was discussed in the post NODC Ocean Heat Content (0-700 Meters) Versus GISS Projections (Corrected). In a communication with Roger Pielke Sr., James Hansen of GISS predicted an OHC accumulation of approximately 0.98*10^22 Joules per year. But the trend of the current version of the NODC OHC data (the observations) is approximately 1.5% of that GISS projection. That is, GISS projected a significant rise, while the observations have flattened significantly in recent years. The reasons for the divergence between observations and the GISS Projection were discussed in Why Are OHC Observations (0-700m) Diverging From GISS Projections? In short, GISS appears to have based its projection on the rise in OHC from the early 1990s to the early 2000s, assuming the rise was caused by changes in manmade factors and that the effect of those anthropogenic forcings would continue unabated into the future. But GISS failed to consider that the vast majority of the rise during the early 1990s to the early 2000s was caused by natural variables such as El Nino/La Nina events, the North Atlantic Oscillation, and the like, not by manmade forcings.
Figure 2

The earlier version of that graph…
…shows a linear trend of ~0.08*10^22 Joules/year. The current linear trend is ~0.015*10^22 Joules/year.

In the numerous posts on the NODC OHC data that precede this one, I don’t believe I’ve presented linear trend comparisons. Looking at the OHC linear trends for the individual ocean basins, Figure 3, it is very evident that the North Atlantic played a major role in the rise of global OHC since the early-to-mid 1970s. The linear trends of the OHC for most ocean basins, excluding the North and South Atlantic, are between 0.047 and 0.066 GJ/meter^2/decade. The linear trend of the North Atlantic OHC (0.205 GJ/meter^2/decade), on the other hand, is approximately 3 to 4 times those values. The South Atlantic OHC trend falls in between, suggesting an influence of the North Atlantic on the South Atlantic.
Figure 3

IF the multi-decade variations in North Atlantic OHC are similar in timing to the AMO, and IF the AMO did peak in 2005, and IF (lots of big IFs) the decline in North Atlantic OHC persists for another two plus decades, will global OHC continue to remain flat (or decline) for that long, too? Many of the other ocean basins are showing recent flattening or declines, so the North Atlantic is not alone. Regardless, a long-term decline in North Atlantic OHC (if one were to occur) would definitely not help long-term projections of a monotonous rise in OHC. And since the only variables that appear to cause significant rises in the other ocean basins are multiyear La Nina events and shifts in sea level pressure, a continued drop in North Atlantic OHC would have to be counteracted by one of those other factors.

The following are links to earlier posts that illustrate and discuss how natural variables (including ENSO events and changes in sea level pressure as represented by the North Atlantic Oscillation and North Pacific Index) are responsible for most of the rise in OHC since 1955:
ENSO Dominates NODC Ocean Heat Content (0-700 Meters) Data,
North Atlantic Ocean Heat Content (0-700 Meters) Is Governed By Natural Variables,
North Pacific Ocean Heat Content Shift In The Late 1980s

Figures 4 through 6 are comparison graphs of global and hemispheric OHC linear trends and the OHC linear trends for the individual ocean subsets per hemisphere.
Figure 4
Figure 5
Figure 6

For those who enjoy information overload, the following are time-series graphs of OHC data (0-700 meters) for the globe, hemispheres, and the individual ocean basins.

Note: I have no plans to perform comparisons of the data for the individual basin OHC anomalies before and after the revisions to the 2006-and-later data. I have compared the graphs I have on file, and the revisions do appear to have impacted all ocean basins. For those who wish to confirm this, you would have to download all of the following graphs, and also download the graphs from the post Update NODC (Levitus et al 2009) OHC Data Through June 2009 (Corrected). The color coding for the ocean basins have remained the same, with the exception of the Southern Ocean. The sizes of the images may vary slightly, but the corrections are still visible.

One last note: As opposed to presenting the OHC for the NINO3.4 region of the equatorial Pacific, I’ve included Tropical Pacific OHC data in the update. Here are graphs of the updated data without commentary:
Figure 7 - Global OHC
Figure 8 - Northern Hemisphere OHC
Figure 9 - Southern Hemisphere OHC
Figure 10 – Tropical Pacific OHC
Figure 11 - North Atlantic OHC
Figure 12 - South Atlantic OHC
Figure 13 - North Pacific
Figure 14 - South Pacific
Figure 15 - Indian Ocean
Figure 16 - Arctic Ocean
Figure 17 - Southern Ocean

NODC Annual Global OHC data used in Figure 2 is available here:

The other graphs of NODC OHC data were created from data provided by the KNMI Climate Explorer website:


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