Dr. Roy Spencer sent me a notice of his most recent post in email. He offers an invitation for anyone to help “figure this one out”. The result could be “worse than we thought”. – Anthony
(edited 8/23/09 0710 CDT: Changed plots & revised text to reflect the fact that NCDC, not CRU, is apparently the source of the SST dataset; also add discussion of possible RFI interference in satellite measurements)
(edited 8/22/09 1415 CDT: added plot of trend differences by month at bottom)
By Dr. Roy Spencer
In my previous blog posting I showed the satellite-based global-average monthly sea surface temperature (SST) variations since mid-2002, which was when the NASA Aqua satellite was launched carrying the Advanced Microwave Scanning Radiometer for EOS (AMSR-E). The AMSR-E instrument (which I serve as the U.S. Science Team Leader for) provides nearly all-weather SST measurements.
The plot I showed yesterday agreed with the NOAA announcement that July 2009 was unusually warm…NOAA claims it was even a new record for July based upon their 100+ year record of global SSTs.
But I didn’t know just HOW warm, since our satellite data extend back to only 2002. So, I decided to download the NOAA/NCDC SST data from their website — which do NOT include the AMSR-E measurements — to do a more quantitative comparison.
From the NOAA data, I computed monthly anomalies in exactly the same manner I computed them with the AMSR-E data, that is, relative to the June 2002 through July 2009 period of record. The results (shown below) were so surprising, I had to go to my office this Saturday morning to make sure I didn’t make a mistake in my processing of the AMSR-E data.
As can be seen, the satellite-based temperatures have been steadily rising relative to the conventional SST measurements, with a total linear increase of 0.15 deg C over the 7 year period of record versus the conventional SST measurements.
If the satellite data are correct, then this means that the July 2009 SSTs reached a considerably higher record temperature than NOAA has claimed. The discrepancy is huge in terms of climate measurements; the trend in the difference between the two datasets shown in the above figure is the same size as the anthropogenic global warming signal expected by the IPCC.
I have no idea what is going on here. Frank Wentz and Chelle Gentemann at Remote Sensing Systems have been very careful about tracking the accuracy of the AMSR-E SST retrievals with millions of buoy measurements. I checked their daily statistics they post at their website and I don’t see anything like what is shown in the above figure.
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.
UPDATE #1 (8/22/09)
Here’s the trend differences between the satellite and in-situ data, broken out by calendar month. The problem seems to be mainly a Northern Hemisphere warm season phenomenon.
UPDATE#2 (8/23/09)
Anthony Watts has suggested that the radio frequency interference (RFI) that we see in the AMSR-E 6.9 GHz data over land might be gradually invading the ocean as more boats install various kinds of microwave transmitters. While it’s hard for me to believe such an effect could be this strong (we have never seen obvious evidence of oceanic RFI before), this is still an interesting hypothesis, so this week I will examine the daily 1/4 deg. grids of AMSR-E SST and compute a spatial “speckle” statistic to see if there is any evidence of this kind of interference increasing over time. I should note that we HAVE seen more RFI reflected off the ocean from geostationary TV communication satellites in the AMSR-E data in recent years.
UPDATE#3 (8/24/09)
OK, gang, this is what I found out today before having to leave work. I downloaded the monthly grids of SST from NCDC (both their v2 and v3b products), and I computed the monthly anomalies at each gridpoint relative to the June 2002 through July 2009 period (since that is the period we have AMSR-E measurements for).
I then differenced the later part of the period (since 2007) with the earlier part (during and before 2004), separately for the NCDC and AMSR-E products.
Then I differences THOSE differences.
What it shows is that AMSRE has either spuriously warmed, or NCDC has spuriously cooled, by 1 to 2 deg C over all of the ‘warmer’ waters of the globe. The problem seems to diminish and then go away poleward of about 30S latitude, and poleward of 45N latitude.
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. 🙂
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http://www.ssmi.com/amsr/amsre_sst_validation_statistics.html#amsre_sst_compared_to_in_situ_sst
Look at the first chart comparing drifting bouys and moored ones. The drifing bouys throughout most of July show a consistantly higher reading. I am sure our more technical writers can determine if there is anything to this.
My article “global cooling has arrived, global warming is dead” commissioned by the London branch of the Institute of Physics for their Autumn newsletter has been suppressed and will now not be published. The real reason is because it opposses global warming! This story hit the Times Higher Education edition last week with the IOP saying they do not suppress articles. They say my article should have been peer reviewed. this is nonsense as none of the fifty groups in the IOP have ever had their newsletter articles peer reviewed! One does not have to be a scientists to follow my article. A similat article was published in the Belfast Telegraph on 13 May. See http://www.belfasttelegraph.co.uk click on environment and scroll down to 13 May.
Reply: Is there some reason you didn’t just link directly to your article? ~ ctm
Tom in Florida (11:49:17) :
http://www.ssmi.com/amsr/amsre_sst_validation_statistics.html#amsre_sst_compared_to_in_situ_sst
Look at the first chart comparing drifting bouys and moored ones. The drifing bouys throughout most of July show a consistantly higher reading. I am sure our more technical writers can determine if there is anything to this.
Is this trend only for July? what about the previous months?
Speculation: warm currents drag the drifting ones, which never sample the colder upwelling that the moored ones must at times by construction.
You mention the CRU.Note the recentletter from R. C E Wyndham, co-signed by M. Khandekar and others sent to Professor Robock of the American Geophysical Union concerning the withdrawal from the net of data from CRU. In particulat they are concerned about the position of Dr P Jones who according to them does not permit independent examination of the data and again according to them also refuses to publish raw data. Is this true?
We’ve had some changes in ocean circulation SST effects, e.g., PDO, AMO, AO, could this imply lack of appropriate coverage and overreliance on interpolation?
SSTs this extreme should be having an effect on weather not observed this summer, e.g., Canada and corn belt US are well below norm indicating Arctic/Temperate interface is south of normal, the obverse of that expected.
Dr. Roy
Could the contraction of the atmosphere, driven by the very low solar cycle be influencing how the temperatures from Aqua are measured?
Dr Spencer
What’s fishy?
1) First the concept of a global sea temperature is even more flawed than that of a global surface temperature.
2) From buoys it is derived from an absurdly small number of data points-satellites have their own inherent problems.
3) The sea continually mixes-a patch of warm water can shift from one hour to the next and either be read or drift away.
4) Seven years is an absurdly short period from which to read any meaningful data
Below is the executive explanation of changes and reconstruction of existing figures from 2008- which now excludes satellite data.
http://www.ncdc.noaa.gov/oa/climate/research/sst/papers/merged-product-v3.pdf
This is the detailed document from which the executive statement comes.
http://www.ncdc.noaa.gov/oa/climate/research/sst/papers/SEA.temps08.pdf
It must be remembered that Historic global SST data is even more sparse than surface global temperatures. Both have their genesis in James Hansens’ 1986 document which seems to have aquired a factual scientific basis from which fractions of a degree are calculated.
http://pubs.giss.nasa.gov/docs/1987/1987_Hansen_Lebedeff.pdf
We may know SST from extremely localised locations for a few decades-for example Plymouth UK- but it is surely not wise for us all to pretend this is a finely tuned science, and we know all the answerrs. Heck, we dont even know the right questions!
In short, parsing nonsensical figures will result in nonsensical answers.
Keep up the good work-I find your information very interesting.
tonyb
I’ve updated this article with trend differences by calendar month…it appears the problem is mainly during the N.H. warm season.
http://www.drroyspencer.com/2009/08/somethings-fishy-with-global-ocean-temperature-measurements/?preview=true&preview_id=943&preview_nonce=cc45113817
Dr Spencer
Sorry, the above comments were phrased for the general audience we get here, obviously you already know all this stuff and much much more!
Tonyb
And how a trace gas like CO2 influences the ocean temperature again? The amount of CO2 dissolved surely has nothing to do with that.
Orwell – “”He who controls the present, controls the past. He who controls the past, controls the future.” ”
Climate Science — he who controls the “adjustments” controls the “data”.
My first reaction is to question Jim Hansen’s NASA. You know… Normal Anthropogenic Supplemental Adjustment, Normally Adjusted Somewhat Above.. yeah, that NASA. The same guys looking for a roughly +2.4º El Nino SST anomaly based on AGW forcing.
I’d like to see some -RAW- ARGO data to put next to this, not the filtered by warmers stuff.
Looking higher in the directory of…
ftp://ftp.ncdc.noaa.gov/pub/data/anomalies/monthly.ocean.90S.90N.df_1901-2000mean.dat
… I find a read-me file…
ftp://ftp.ncdc.noaa.gov/pub/data/anomalies/README
…that states only:
“In July 2009, NCDC transitioned to the use of an improved Global Land and Ocean data set (Smith et al., 2008) which allows better analysis of temperatures throughout the record, with the greatest improvements in the late nineteenth century and since 1985. Improvements in the late nineteenth century are due to improved tuning of the analysis methods.”
That’s a fairly recent change (last month).
If the SST’s did indeed rise or is rising to apocolyptic levels the recorded surface temps. I would guess would easily suggest August would be a bit wamer than July globally.
However while this shows it is above the norm it doesn’t look like it will show another significant rise from July
http://discover.itsc.uah.edu/amsutemps/execute.csh?amsutemps
I would guess with that data you’d expect the 2009 line for the last 2 or so weeks to be quite a bit higher than it is now considering how rapidly SST’s would’ve warmed if you believe the data.
The trend differential between AMSE-R minus the CRU SST in-situ data as well according to the RSS validation data.
The average is +0.035C per decade but there is wide dispersion amongst the different methods of in-situ measurement:
+0.066C per decade for ship engine intake
-0.104C per decade for moored bouys
-0.027C per decade for drifting bouys
+0.077C per decade for ship bucket
+0.165C per decade for ship hulls
So, perhaps there is more warming in the Ocean SSTs but the ship-based measurements are adding in a cooling trend to the in-situ CRU SSTs.
Hmmm, the link in my last post returns an error, let’s see if this link will work?
http://discover.itsc.uah.edu/amsutemps/execute.csh?amsutemps
If not then it’s supposed to be the link to the UAH site to the channel Mr. Spencer uses.
Look at 2003. CRUT was much Higher than you. Sometimes you pick up something they don’t. Sometimes, they smear the red crayon out a little too far from one of their sensors.
It’s just an example of using old, inefficient tools, vs using new, modern efficient ones.
All global warming/climate change just the imagination of the most famous new age scientist and NOBEL prize AG?
Have you seen the Y axis for temperature anomaly?. Are not those tiny mini tempertures differences most probably instrumental?.
Al what is needed it is to change scale to 1 grade and you get a straight line.
Dr. Roy and Anthony:
The NCDC SST Anomaly data…
ftp://ftp.ncdc.noaa.gov/pub/data/anomalies/monthly.ocean.90S.90N.df_1901-2000mean.dat
…is the NCDC’s ERSST.v3b data…
ftp://eclipse.ncdc.noaa.gov/pub/ersstv3b/pdo/aravg.mon.ocean.90S.90N.asc
…except it has the years 1901 to 2000 as its base years, instead of the “normal” NCDC SST climatology.
The ERSST.v3 data was released last year with much fanfare, trumpets blowing, a paper to describe the how the new dataset incorporates satellite data. A few months later they stopped updating it. Then back in November, I think, they re-released it with the satellite data removed as ERSST.v3b. The satellite data was causing a downward bias that some users didn’t like. In other words they bent under peer pressure. I’ve done a couple of posts on this dataset.
http://bobtisdale.blogspot.com/search?q=ersst.v3b
Give me a few minutes to finish the graphs.
That’s an awfully short interval upon which to base a climatology, with a sample size of only n = 7 for each month — pretty unstable — especially with the large anomaly occurring right at the end (maximum leverage in regression) ….and due to the nature of how anomalies are constructed, that outlier drives earlier July anomalies down (some of which are below the x-mean, supplying more leverage).
If the AMSR-E SST series was available in monthly-format, I’d be inclined to break the analysis down by month, performing detailed diagnostics. My guess is that the regression model assumptions are nowhere near being met (non-normal errors, outliers, perhaps autocorrelation).
Does anyone know where monthly AMSR-E SST summaries can be found in plain-text format on a plain webpage?
(…and if not, does anyone know why something so standard & simple is not available?)
Ships and buoys obtain thermometric readings from different layers of near-surface water. Microwave measurements are a totally different animal, which I suspect more closely follows surface skin temperature, rather than layer temperature. Since the skin is evaporating rapidly (~100skins/day*), one should not expect high coherence. The skin is absorbing all the LW backradiation; the subsurface layers are essentailly insulated from it, with only minor conductive transfer downward. It might prove as basic as that.
*That’s better than Lee Trevino ever did!
So much for the unfounded criticisms that WUWT never has any “warming” stories.
Dear Dr. Spencer,
could you kindly sketch, how the AMSR-E instrument works. Is it scanning microwaves emitted from the sea surface, probably at 89 GHz, which would be the tale of the Planck spectrum? The tale intensity would contain the temperature T of the emitter.
In wikipedia it is stated that the atmosphere gets opaque for microwaves above 300 GHz (1 mm wavelength). Is there atmospheric absorption below 300 GHz, and if so, how do you correct for it?
Do you know, what is the atmospheric absorption mechanism above 300 GHz?
Do you measure during the day, or only at night?
Roy Spencer (12:21:06) : This is off topic, but I can’t seem to get an email to you. I’m curious about your efforts to tease out the feedback signal in the satellite radiation data. Have you done any assessment of the regional variation in results? I’m curious because I want to see how the results for the Tropics as covered by ERBE from Lindzen and Choi compare with the same region in your results.
On topic…hm, this is rather, uh, goofy. Maybe it’s time to revisit the buckets issues again?
http://www.climateaudit.org/?cat=67
We’ve found one case already where satellite drift was unexpeceted, but was biasing otherwise accurate temeprature recrods.
Repeated here – but the other way? A steady, but small, change in instrument readings/increasing instrument error since the launch date?
I’d repeat the original “calibration” back to the original comparision measurement locations today – look for a difference between the areas that had been used for calibration then and now. The numbers will be different of course, but the differences may show that drift.