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.
Based upon comments I have read here and elsewhere, I have removed the 4th order polynomial fit to the UAH global temperature graph at my website, drroyspencer.com. I considered reverting to just a simple linear trend line, but it too would have the same fundamental problem that any statistical fit to the data has: people tend to mentally extrapolate that smoothed curve (or line) into the future.
Flanagan (02:39:53) :
“Anywayn the anomaly is much larger than last year, same time. Must be the 7th warmest ever or so…”
It’s the 15th actually…
Flanagan, do you know why the anomaly in Apr 2009 is warmer than last year? What might have been happening globally to produce this jump this year or the decrease last year? And don’t say weather. Be specific. There are cyclic reasons for colder or warmer months when compared to one another from year to year. In fact, with archived jet stream data and SST’s, there are reasonable, definable, solidly based in atmospheric science, demonstrable, repeatable, natural cyclic explanations for every spike up or down and every point in-between on this graph, much of which is now available to the public on a daily basis. If every spike up or down can be explained thusly without any left over heat or cold to explain using man-made warming theories, at the very least, AGW is one of many theories out there that are competing for the more plausible natural cyclic theory.
Let’s just start with a simple one. What might be causing the pumping nature of the line graph? It is quite clear that there is a beat to the measure. Is that artifact? Seasonal heating and cooling? Some oscillation somewhere? It certainly does not coincide with the regular and fast beat of CO2 measures from Mauna Loa. What is making this slightly irregular and noisy but obvious beat? Can all the up beats and down beats be explained by the same set of circumstances?
jeez and slowtofollow
In my analogy, the refrigerator is ‘ideal’ and the motor adds no heat.
And by snow, I mean any precipitation that is frozen (i.e. has given up its latent heat).
Pamela:
The large month-to-month temperature variability is dominated by tropical intraseasonal oscillations in the transfer of heat from the ocean to the atmosphere. It’s not a radiative effect, but a non-radiative one. Higher than average surface winds over the tropical oceans lead to greater than average evaporation rates (cooling the surface), and then higher than average precipitation rates, heating the atmosphere.
Note that they would not exist if we did not have two very different heat reservoirs — the ocean and the atmosphere — exchanging energy in an episodic fashion.
As large as those fluctuations seem, they represent only about 1% variations in the average rate of infrared energy loss to space (or solar energy gain from the sun).
-Roy
Where will it have given up its latent heat and what effect would this have had on its local surroundings at the time?
It will have given up its latent heat the same place as it always does – the atmosphere.
Exactly where I don’t know and it doesn’t matter; conservation of energy says if it has given up heat that heat’s gone somewhere!
“”” Andrew Chantrill (01:10:27) :
Re George Smith:
“The sea water cannot freeze until it gets down to the freezing point temperature, and also until the latent heat of freezing is removed as well; and the only place for it to go, is into the atmosphere, and out into space.
So the freezing doesn’t raise the air temperature; the colder air sucks out the excess thermal energy so that freezing can occur.
I don’t believe anybody ever observed the air temperature to rise while the ocean freezes.”
I agree with you when it comes to sea water freezing, but what about snow landing on Antarctica and building up there? If the snow landed instead in the ocean or on land and melted, it would absorb heat. By not doing so it effectively raises the temperature of the rest of the planet.
Where is the error in the logic? “””
Andrew, first of all, in order for snow to fall, it must first form; i.e. freeze, so it has already given up its latent heat to the atmosphere; at whatever altitude the snow formed.
If it Lands on Antarctica; most of the time it isn’t going to melt, given the typical Antarctic surface temperature.
If it lands in the ocean, hwether it melted or not would depend on the ocean surface temperature; which could be below zero; in which case the snow would persist, and could from into sea ice.
But let’s say it lands in the ocean and does melt. Well then it certainly is going to take up the latent heat of freezing (80 calories per gram); and that energy is most likely to come out of the sea water, given the relative thermal properties of water and air. So the melting snow is no different from melting sea ice; it is going to cool a large amount of sea water, and cause it to shrink; so the sea level will go down. Presumably the water that formed the snow originally came from the ocean, so the total ocean water content isn’t changing; but the warmer ocean water evaporated taking lots of energy into the atmosphere (about 545 cal per gram latent heat of evaporation, and then it dumps out another 80 cal per gram in turning into snow; and all that energy is delivered to the upper atmosphere for radiation to space.
So the whole cycle of evap/snow formation/ocean precipitation, and snow melting, is a huge transfer of thermal energy from the ocean to the atmosphere to be lost to space.
Let me repeat what George E Smith said:
Further, evaporation, formation of water dropplets and precipitation (rain) is another form of this …
You got that right Richard ! Just missing the 80 calories is all; but I’ll settle for the 545 anyway.
George
It’s nice to see Dr Roy himself drop in here to comment. I’m glad he decided to remove his fourth order curve fit.
The key point is NOT that the curve goes wonky when extrapolated outside of the data series time limits; but of course it is equally wonky inside; so interpolation doesn’t work either, to derive values for unmeasured points; there being no underlying physical cause for the shape. I do applaud his attempt to show some shape to the data; because my eye says there does seem to be some shape to at least the second half of the time frame (1998 excepted and understood); But Roy, it is just natural variability.
And my intent was not to jump heavily on the good Dr’s toes. We need to see the data as it comes out of the oven; after all there is no way for us to predict what the next plotted point will be; or even its direction from the latest; so we need to see the numbers as they are released.
George
It’s not on the front page any more, so I doubt that anybady still reads this thread, but GISS is now out for April – 0.44C ( a slight drop from 0.47C in March). Waiting fot HadCrut It still seems that this month again UAH is the “odd one”, as RSS is a slightly up (o.194 to 0.202), GISS is slightly down (0.47 to 0.44) and UAH has a huge drop (0.206 to 0.091)…
NCDC is out as well and puts UAH in even more of a minority.
HADCRU should be out in the next day or two.
I have to admit UAH definately seems to have a problem somewhere.