The data is out for both RSS and UAH, and I’m presenting them both here. Click for full sized graphs.
RSS from Remote Sensing Systems of Santa Rosa, CA. RSS data here (RSS Data Version 3.2)
UAH from Dr. Roy Spencer, University of Alabama, Huntsville. Reference: UAH lower troposphere data
Since Dr. Spencer released the April UAH data first on his own blog, I’ll give him the honor of explaining the data and possible reason for divergence of the two data sets.UAH Data
YR MON GLOBE NH SH TROPICS
2009 1 0.304 0.443 0.165 -0.036
2009 2 0.347 0.678 0.016 0.051
2009 3 0.206 0.310 0.103 -0.149
2009 4 0.091 0.126 0.055 -0.010
Once again there is a rather large discrepancy between our monthly anomaly (+0.09 deg. C.) and that produced by Remote Sensing Systems (RSS, +0.20 deg. C). We (John Christy and I) believe the difference is due to some combination of three factors:
1) we calculate the anomalies from a wider latitude band, 84S to 84N whereas RSS stops at 70S, and Antarctica was cooler than average in April (so UAH picks it up).
2) The monthly anomaly is relative to the 1979-1998 base period, which for RSS had a colder mean period relative to April 2009 (i.e. their early Aprils in the 1979-1998 period were colder than ours.)
3) RSS is still using a NOAA satellite whose orbit continues to decay, leading to a sizeable diurnal drift adjustment. We are using AMSU data from only NASA’s Aqua satellite, whose orbit is maintained, and so no diurnal drift adjustment is needed. The largest diurnal effects occur during Northern Hemisphere spring, and I personally believe this is the largest contributor to the discrepancy between UAH and RSS.
UPDATE: Basil Copeland writes in comments.
And for those who are unhappy with either linear or 4 order polynomial trends, may I suggest Hodrick-Prescott smoothing?
http://i40.tinypic.com/30ngom0.jpg
I like to also keep track of the USA48 UAH anomalies:
The USA48 series appears flatter than the global series. That’s an illusion created by the differences in scale. The global series is not as volatile as the USA48, because it averages out all kinds of regional variation in climate around the globe. The scope of this averaging can be seen by plotting the two together, on the same scale:
http://i41.tinypic.com/2rw8bhw.jpg
The “Average Decadal Change Rate” shown on the chart is calculated as 120 times the average 1st difference of the smoothed trend lines, a number that should be fairly immune to any claims of cherry picking.
Frankly, I was surprised. E.g., on its own, the USA48 chart looks flatter. But it isn’t, really. In fact, it is steeper. Before anyone concludes that the high rate of growth for USA48 somehow demonstrates AGW, do keep in mind that during most of this time frame, the PDO was in a warm phase, and that the PDO warm phase has a strong influence on continental US temperatures.
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That wider latitude coverage from UAH might explain the wider swings in variation on the UAH graph when compared to the RSS graph – at least it seems that way from just eyeballing the two.
I think we can expect to see falls for several months, in line with SST’s from a few months ago.
My thanks to John Christy and Roy Spencer, and the RSS team for their valuable work.
It is starting to look really flat…
Or if you check out the trends, almost like a hockey stick (going down, not up)
http://tinyurl.com/cjguzg
Dr. Spencer’s explanation is for the difference between UAH and RSS but UAH is also very different from daily amsu readings. It was aiming more towards 0.19C or 0.2C than 0.09C. Not once in the month did the channel 5 anomaly go under 0.1C?! I think UAH should check and recheck, something is not right…
http://discover.itsc.uah.edu/amsutemps/
So, the question I ask is on whose side is RSS? If they are pro AGW, then the narrower scan would tend to show less of a cooling trend.
Although we have the quietst sun of the century, although al oceanic ocillations are deep negative…still we have a positive temperature anomaly. I am still waiting for that global temperature to drop below the zero anomaly.
They answered me here on this blog before that I have to wait another 5year before all these cooling parameters would become visible in the temperature. The I ask myself the question how it was possible to establish the direct relationship between the sun activity and oceanic oscillations and the temperature. In all these publications I have read only about a lag of maximum 6 months.
Thus if the higher global temperature anomalies are simply explained by natural factors…then one of the next months the global temperature has to drop (far) below the zero-anomalie ?
whats happened to icecap? It seems to be non-existant since yesterday
I did not read Sven’s comment on AMSU-A, before I calculated the AMSU-A difference for April (Ch04) between 2009 and 2008. I found 0.173 Celsius, while the global UAH difference is 0.076 Celsius.
Taking AMSU-A at face value, adding 0.173 to the 4/2008 UAH value of 0.015 is 0.188 Celsius, close to the 4/2009 RSS value of 0.202 Celsius.
Channel 04 is the default value on the AMSU-A website, but to compare with UAH, I probably should have taken Ch05, as Sven did.
Dr. Spencer, please explain.
Sven; I tend to think there also might be a problem this month. But I don’t know if it was in the daily temperatures or the final figures. Maybe we should wait for GISSTemp and HadCrut in order to get a better view. Satellite temps are highly fluctuating, so they’re sometimes misleading. For example, it really looks like the 79-90 period was completely flat on the graph. Maybe they should think about plotting uncertainties?
OT but Just got Ian Plimers book. It will be the “Bible” of truth about AGW. Extremely well referenced and poignant.
I have no difficulty accepting the small differences in these two charts. The suggested reasons for the differences make sense. Thus, the emphasis ought not to be on differences but rather on what this almost identical information is showing. Bob Tisdale has commented that the 1998 El Nino released an enormous amount of warm water from the western Pacific – so much so that after the initial burst of heat it still took several sloshings back and forth to work this heat from ocean to atmosphere.
The recent thread on the non-warming ocean ties in nicely. Now overlay these two charts (or for visual clarity, use their average) with CO2 concentration and a median UN-IPCC temperature projection. Shift these over Medieval Warming and Little Ice Age diagrams. Then add a simple 100 word explanation and zap it everywhere. Overload the internet with it. Something must work, but what?
The problem is that the Administration in D.C., Congress, and the AGW zealots have the characteristic opposite that of a Black Hole. How to penetrate the fog is the overriding question of our time!
Thank you for removing the very misleading, unscientific, and totally in-appropriate 4th order poly fit to the curve Dr. Spencer choses to add to his plot.
http://www.drroyspencer.com/latest-global-temperatures/
What is becoming clear is that for the past 30 years there is no upward or downward trend, global temperatures appear to be cyclical indicating natural forcing.
When you consider that the troposphere is meant to be the business end of man-made global warming, i.e. radiative forcing, these null results highlight that all the IPCC climate models are not just in error but are in serious error.
The SST anomaly update for April is here, for those who missed the link by “Adam from Kansas” back on the May 2nd “Michigan Lake Level” thread:
http://bobtisdale.blogspot.com/2009/05/april-2009-sst-anomaly-update.html
Why not just provide an AGW alarmist-type of explanation? For example:
The divergence arises from the fact that RSS aren’t of real scientists, and that they are in the pockets of Big Wind and Big Solar.
Let’s just say the anomaly is somewhere between 0.10 and 0.20°C. I think one tenth of a degree difference is probably within or near the margin of error.
No matter the result you take, the earth is not warming right now.
Does anyone know why http://climate.uah.edu/ is no longer being updated? Is there a different source showing the geographic distribution of the UAH readings?
tall bloke,
Looking at the latest SST, looks like an El Nino could be in the works later this year.
http://www.osdpd.noaa.gov/PSB/EPS/SST/climo&hot.html
Joe Bastardi of Accuweather also predicts one.
http://www.accuweather.com/world-bastardi-europe-blog.asp?partner=accuweather
Sven (23:09:05)
Dr. Spencer’s explanation is for the difference between UAH and RSS but UAH is also very different from daily amsu readings. It was aiming more towards 0.19C or 0.2C than 0.09C. Not once in the month did the channel 5 anomaly go under 0.1C?! I think UAH should check and recheck, something is not right…
I was with you on this – at first, but it seems UAH may not necessarily using the published AMSU data, but data from NASA’s Aqua satellite. See point 3 above which says
“RSS is still using a NOAA satellite whose orbit continues to decay, leading to a sizeable diurnal drift adjustment. We are using AMSU data from only NASA’s Aqua satellite”
On the http://discover.itsc.uah.edu/amsutemps/ site it says
“Daily averaged temperatures of the Earth are measured by the AMSU flying on the NOAA-15 satellite .”
So either the daily temperatures are not used by UAH or the home page needs updating.
He’s right. The RSS data is always drifting higher. If your sensing equipment is depending on a time-length return for signal, a decaying orbit will make your data drift with it.
Sven (23:09:05) :
are you referring to ch04 in the link you give? It has been within 1/2 F of the April 2008. This is consistent with the plots above.
tallbloke (22:57:12) :
I think we can expect to see falls for several months, in line with SST’s from a few months ago.
Whereas surface temperatures may start to increase by comparison since they tend to better reflect the ‘current’ situation. This will, of course, trigger the usual nonsense about data fiddling at GISS in particular. Just remember that over the past few months GISS (1979-1998 base period) anomalies have been well below UAH anomalies.
Sven (23:09:05) :
Dr. Spencer’s explanation is for the difference between UAH and RSS but UAH is also very different from daily amsu readings. It was aiming more towards 0.19C or 0.2C than 0.09C. Not once in the month did the channel 5 anomaly go under 0.1C?! I think UAH should check and recheck, something is not right…
http://discover.itsc.uah.edu/amsutemps/
*******************************
Sven – your reference shows actual temperatures, not anomalies.
How do you access the April 2009 anoms?
Are you assuming the “20-year average” is the 1979-98 baseline for the anoms?
Sped (22:58:51) : It is starting to look really flat…
Or if you check out the trends, almost like a hockey stick (going down, not up)
http://tinyurl.com/cjguzg
You know, it looks almost exactly like what is called a “blowoff top” in stock chart terms. The 1998 spike is the “blow off'” with an abnormally hight peak relative to trend, then followed by a lower peak-let then a failure to advance peer peak-let. Classic, darned near.
I wonder what strange parallel can let two such divergent chaotic systems have such similar chart behaviours… Just fascinating. Like having your dog paw print turn out to be almost identical to your hand print… You just have to wonder what the odds could be…
>1) we calculate the anomalies from a wider latitude band, 84S to 84N whereas RSS stops at 70S, and Antarctica was cooler than average in April (so UAH picks it up).
Anthony how about a bit of balance here – reams and reams on Arctic ice products but not even boo from you about the UAH Antarctic fudge. There is a 3km high reason why you should not go to 84S.
You might also care to report on the linear trends…
UAH trend: +0.13°C/decade
RSS trend: +0.155°C/decade