We should all thank AP’s Seth Borenstein for this, IMHO. Without his article on July SST’s being the hottest ever and it not making much sense, people such as Dr. Spencer may not have been immediately motivated to figure out what was going on with the SST’s. – Anthony
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Spurious Warming in New NOAA Ocean Temperature Product: The Smoking Gun
Dr. Roy Spencer August 27th, 2009
After crunching data this week from two of our satellite-based microwave sensors, and from NOAA’s official sea surface temperature (SST) product ERSST v3b, I think the evidence is pretty clear:
The ERSST v3b product has a spurious warming since 1998 of about 0.2 deg. C, most of which occurred as a jump in 2001.
The following three panels tell the story. In the first panel I’ve plotted the TRMM Microwave Imager (TMI) SST anomalies (blue) for the latitude band 40N to 40S. I’ve also plotted SST anomalies from the more recently launched AMSR-E instrument (red), computed over the same latitude band, to show that they are nearly identical. (These SST retrievals do not have any time-dependent adjustments based upon buoy data). The orange curve is anomalies for the entire global (ice-free) oceans, which shows there is little difference with the more restricted latitude band.
In the second panel above I’ve added the NOAA ERSST v3b SST anomalies (magenta), calculated over the same latitude band (40N to 40S) and time period as is available from TRMM.
The third panel above shows the difference [ERSST minus TMI], which reveals an abrupt shift in 2001. The reason why I trust the microwave SST is shown in the following plot, where validation statistics are displayed for match-ups between satellite measurements and moored buoy SST measurements. The horizontal green line is a regression fit to the data. (An average seasonal cycle, and 0.15 deg. C cool skin bias have been removed from these data…neither affects the trend, however.)
I also checked the TMI wind speed retrievals, and there is no evidence of anything unusual happening during 2001. I have no idea how such a large warm bias could have entered into the ERSST dataset, but I’d say the evidence is pretty clear that one exists.
Finally, the 0.15 to 0.20 deg. C warm bias in the NOAA SST product makes it virtually certain that July 2009 was not, as NOAA reported, a record high for global sea surface temperatures.
UPDATE: Dr. Spencer has an update to this post here:
http://wattsupwiththat.com/2009/08/31/spencer-always-question-your-results/
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http://washingtontimes.com/news/2009/aug/25/bury-the-messenger
Nice work. I will be interested in the response.
The fit for the second graph would be improved if the ERSST data has its zero point lowered by 0.4C and the amplitude increased by 25%. Same conclusion, though.
I’m late to the party on this issue. With that in mind…
Question, is it possible to expand the graph to include a period before 1998? It would be interesting to see how past readings line up.
Hmm. Did they add a different set of buoys in 2001?
Ah, so T. Karl’s dissing of the satellite data is off the mark, as far as he can know.
Roy Spencer’s analysis certainly suggests that there is no SST record, but I’m not sure it explains the puzzling divergence of trends between AMSR-E and NOAA data which was the basis of the original post.
Is it possible that some sort of gradual correction is taking place with the NOAA data.
And then there’s the shift in Hadley Centre’s HADSST product in 1998 due a change in datasets from their provider…
http://bobtisdale.blogspot.com/2008/12/step-change-in-hadsst-data-after-199798.html
stephan meijer (14:22:27) “The record ocean temperature for July was due to great warming of the waters near the antarctic according to satelite data.”
I don’t see any anomalous hot-spots around Antarctica on this global SST anomaly map for July 2009:
http://nomad3.ncep.noaa.gov/cgi-bin/pdisp_sst.sh?ctlfile=monoiv2.ctl&ptype=map&var=ssta&level=1&op1=none&op2=none&month=jul&year=2009&proj=default&lon0=280&dlon=50&lat0=-60&dlat=60&type=shaded&cint=def&white=def&plotsize=800×600&title=&dir=
Can you direct us to a link that contradicts this Southern Ocean pattern for July 2009?
Paul, here’s the UAH Vortex Data:
http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt
It shows the warmest water (1.08) at the South Pole.
The S. Pole, land anomaly was 3.11
Paul Vaughan (17:20:11) :
“Can you direct us to a link that contradicts this Southern Ocean pattern for July 2009?”
This NOAA map show the antarctic ocean very warm!
http://www.cdc.noaa.gov/map/images/rnl/sfctmpmer_07a.rnl.html
Okay, I’m lost. This whole brouhaha started because the “Aqua” data was considerably warmer than the NOAA Data, right?
But, now the “problem” is that the “NOAA” data was too warm?
Does that mean the “AQUA” Data was WAY Too Warm?
And, we’re “Proving” this by comparing various data sets at 40 – 40?
And, might I remind everyone that for the last six years UAH, and NOAA were in pretty much Perfect Agreement.
I think we’re all getting a little “deep into the weeds,” here. Satellites, and Buoys are going to vary from time to time. They just are.
The smartest of people can overlook the simplest of things.
pochas (17:55:58)
This NOAA map show the antarctic ocean very warm!
http://www.cdc.noaa.gov/map/images/rnl/sfctmpmer_07a.rnl.html
That’s air temperature.
Here is the view for SST:
http://www.cdc.noaa.gov/map/images/sst/sst.anom.gif
pochas (17:55:58) :
Paul Vaughan (17:20:11) :
Regarding: NOAA map
All the orange and red on this map occurs near 70 degrees South Latitude where the areal exaggeration is considerable. Another case of how to mislead with cartographic precision. I assume the actual reported numbers are from real data and not this stretched version.
stephan meijer: You wrote, “The record ocean temperature for July was due to great warming of the waters near the antarctic according to satelite data. So it makes sense the warming between 40N-40S has not broken a record in July. From my understanding this satelite data has only been available since 30 years, so to claim that the July ocean temperatures are the highest in 130 years seems not right to me.
I am interested to find out what you guys think of this and perhaps include some of this antarctic warming in your graphs?”
The Southern Ocean SST anomalies don’t show a recent rise in the OI.v2 (satellite-based) SST anomaly data:
http://i29.tinypic.com/9ubsec.png
There aren’t any Southern Ocean (poleward of 60S) hotspots either:
http://i32.tinypic.com/ilanx5.png
Both of those links are from my July 2009 SST anomaly update here:
http://bobtisdale.blogspot.com/2009/08/july-2009-sst-anomaly-update.html
Over a longer term, the Southern Ocean SST anomalies have been dropping since the early 1990s:
http://i41.tinypic.com/29zxus7.jpg
From my post about the ERSST.v3b version of the Southern Ocean SST anomaly data:
http://bobtisdale.blogspot.com/2009/04/closer-look-at-ersstv3b-southern-ocean.html
What’s the source of your thought that there has been a “great warming of the waters near the antarctic according to satelite data?”
Paul, you’ve put up SST’s for July 1, and Aug 22.
You’ve got it bracketed. Now, fire for effect.
🙂
I was swimming in the ocean on that day in 2001. I don’t remember the water getting suddenly warmer.
Anthony,
It might be worth highlighting that Dr. Spencer originally pointed out that the inconsistency could mean that the surface records could be underestimating the warming:
“Is it possible that the NCDC SST temperature dataset has been understating recent warming? I don’t know…I’m mystified. Maybe Frank, Chelle, Phil Jones, or some enterprising blogger out there can figure this one out. ”
He aslo acknowledged his own fallibility by admitting that whatever was wrong could be his fault when he said:
“This does NOT look like an RFI issue…it is too uniform spatially. Someone has made a major boo-boo…and I hope it isn’t me. :)”
In the past, Dr. Spencer has also identified errors that resulted in spurious cooling in the RSS data set.
I mention this because there will be inevitable criticism that Dr. Spencer was only looking for something that confirmed his point of view. Fortunately, the public record makes it clear that he was looking for any explaination that would explain the inconsistency – even if it made him look bad.
REPLY: I agree, see Dr. Spencer’s response below. – Anthony
Thank you Mr. Spencer for finding that. You definitely get a gold star from the teacher.
(you did it before that auditor fellow too 😉 )
For those of you who are confused that my original post suggested that July 2009 might be even WARMER than NOAA reported, and now I’m showing that it is actually the other way around, well, the answer is quite simple….
I screwed up with my original coding.
These different datasets have different spatial resolutions, some start at the north pole, some start at the south pole, some start at Greenwich, some start at the dateline. I ended up having a bug in the way I was sampling the latitude bands.
So, I went back and started coding from scratch, and tried to use the same procedures as much as possible for all three datasets I analyzed. I’m quite confident in the results now…but I still hope someone else (maybe at NOAA?) will try to do a similar comparison.
The error could also be noted as 0.25C in 10 years or 2.5C in 100years.
An intentional trent modificaton?
This is bang on if they were hoping to reach thier predicted warming in 2100:
http://en.wikipedia.org/wiki/File:Global_Warming_Predictions.png
Kum Dollison (17:40:53) “here’s the UAH Vortex Data:
http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt
It shows the warmest water (1.08) at the South Pole.”
Thanks for pointing this out. Upon a quick glance, this does not appear consistent with other series ….so here’s yet another discrepancy to ponder ….but:
–
Kum Dollison (18:13:04) “I think we’re all getting a little “deep into the weeds,” here. Satellites, and Buoys are going to vary from time to time. They just are.”
I’ll agree that discrepancies in short-term fluctuations shouldn’t be immediately all-consuming as soon as they arise, but add that at the same time I’m pleased to see people watching for data-integrity like hawks.
–
Could this discrepancy be related to the “skin” theme?
I don’t see any further comment on this Cold Lynx posting that appears to point to a change in the 30 year average baseline calculation that was put into the record in August 2001around the time Dr. Spencer says the spurious warming was introduced. I would like to hear from someone qualified to speak to this issue.
Thanks!
Cold Lynx (14:30:06) :
Dr. Roy Spencer wrote “I also checked the TMI wind speed retrievals, and there is no evidence of anything unusual happening during 2001. I have no idea how such a large warm bias could have entered into the ERSST dataset, but I’d say the evidence is pretty clear that one exists.”
The answer?
“So, we constructed a new SST normal for
the 1971–2000 base period and implemented it operationally
at CPC in August of 2001″
From http://www.ncdc.noaa.gov/oa/climate/research/sst/papers/xue-etal.pdf
Further to Paul Vaughan (19:27:12) regarding Kum Dollison (17:40:53)
Are you suggesting “Ocean” means SST and not air-temperature-over-the-ocean?
http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt
The Read-Me files in the directory don’t clarify, but I do note that “Ocean” anomalies are available for lower troposphere, mid-troposphere, and stratosphere ….so that’s a pretty big clue!