May UAH Global Temperature Anomaly – holding steady

With a quiet sun, the Earth’s heat seems to be radiating away. Could be we’re missing something important here about our climate’s link to the full spectrum of solar activity?
The next few months should be interesting!

Watch the Y axis!. I am burning with that increase. Did you feel the difference of half a degree too?, it surely caused the blow up of the gulf rig!

Doctor Spencer: In the race for the hottest calendar year, 1998 still leads with the daily average for 1 Jan to 31 May being +0.65 C in 1998 compared with +0.59 C for 2010. (Note that these are not considered significantly different.) As of 31 May 2010, there have been 151 days in the year. From our calibrated daily data, we find that 1998 was warmer than 2010 on 96 of them.
Can someone please explain what exactly is being compared here? Is the 1998 +0.65 C rise being compared against the same temperature averages as the 2010 +0.59 C (i.e 1979-2010), or against an earlier and lower average (possibly 1967-1998)?

RHS says:
June 4, 2010 at 11:48 am
A statistically significant sample size is dependent on the data and the sample size itself. Going from memory from a Design of Experiments course, I believe 25 – 30 is (barely) enough. The larger the sample size, the higher the level of confidence in the variability in the solution. If I’m not mistaken, the text we used stated something to the effect of:
A sample size of 25 – 30 maybe usable but larger sizes (preferably) in the 1000′s provides a better level of confidence based on the variability in the sample set.
Someone whose expertise in statistics should be able to provide a better answer.
Bueller, Bueller, anybody?
__________________________________________________________________________
Yes, 25 – 30 sample size is the minimum but only if you are fairly sure all the data belongs to the same “process” The first rule of course is to PLOT the data.
If I do that with the cities in my area I see this:
Chapel hill NC
Lumberton NC
Albermarle NC
And another place chosen completely at random:
Moosonee Ont.
HUMMmm, I see what might be a sine wave type pattern to this data. Therefore I would need to choose a sample size that included at least one entire cycle of the pattern. I would prefer three.
However we know there are other cycles and patterns beyond those showing in this data so the more data the better. It is far too early to make decisions on a record that does not contain the complete pattern because it will lead to a major error in the analysis.
There is also the matter or error analysis of the data. A good explanation of that is here

“n the race for the hottest calendar year, 1998 still leads with the daily average for 1 Jan to 31 May being +0.65 C in 1998 compared with +0.59 C ”
Yet when UAH changed from 5.2 to 5.3 the 2010 temperatures changed but 1998 did not.
Are we compairing like with like here?

sky says:
June 4, 2010 at 5:24 pm
That’s what I was thinking, until I checked ever year from 2000 to 2010, and found that it is anomalously warm most of the time. Which should make it normal for it to be warm. In a lot of years, the peristent warm anomaly is offshore, detached from the river by a good distance. So, the river it not the cause, and the anomaly cannot be because of above normal sea temps.
Nothing makes sense.

dennis ward says:
June 4, 2010 at 2:48 pm
“Can someone please explain what exactly is being compared here? Is the 1998 +0.65 C rise being compared against the same temperature averages as the 2010 +0.59 C (i.e 1979-2010), or against an earlier and lower average (possibly 1967-1998)?”
January – May 1998 average 0.65 °C higher than average 1979-1998.
January – May 2010 average 0.59 °C higher than average 1979-1998.
Because the temperature deviations dropped during the year, the deviation for 1998 was +0.52 in the end. This will also happen 2010, no matter if a La Nina will come (but the extend of the decline will depend from this).
2010 will probably end as second warmest year in this series, with a small chance to be the warmest. And 2011 will be colder, that’s already sure.

AndyW says:
June 4, 2010 at 10:18 pm
“In the 15 years from 1979 we had above and below zero on a regular basis, in the last 15 or so years not once below zero, why is that? Have all the cycles changed or is it something else?”
Reference period is 1979-1998, so for this period the average has to be 0.0 °C deviation. The main reasons for year to year fluctuations are El Nino / La Nina overlaid by cooling from vulcano eruptions (El Chichon 1982 and Pinatubo 1991 reduced the global temperature for several years).
A small part of the warming trend can be explained by the vulcanoes: contrary to the reference period there was no eruption with noticable cooling effect after Pinatubo. So because the average temperature 1979-1998 is reduced by vulcanoes, the positive deviations are higher now.
But the main reason is global warming caused by x % natural and y % anthropogenic reasons (x and y depending on your religion).

Sorry, this was a reply to Roger, not to Walter

kadaka (KD Knoebel) says:
June 4, 2010 at 4:02 pm
You like RSS? That’s good to know. From their “Description of MSU and AMSU Data Products” page is found under “Introduction”:
…
Well, ain’t that a startling admission.
Well, I’m glad to see you reading citations. Most people do not, I suspect.
You realize RSS and UAH don’t launch their own satellites, right ?
RSS, UAH and even UW all analyze the same data from the same satellites, launched by NASA:
http://www.ncdc.noaa.gov/sotc/?report=global
http://www.ncdc.noaa.gov/oa/climate/research/msu.html
Notice the North Pole, Land, Ocean temperature anomalies for the latest month of UAH data available at NCDC (April 2010): 2.46° C, 2.31° C, 2.68° C
Look at the Arctic ocean anomalies for Dec 2009: 3.20 ° C
Feb 2010: 2.92° C
No wonder the ice is melting at a record rate this spring:
http://www.ncdc.noaa.gov/oa/climate/research/uahncdc.lt
Although RSS analyzed the exact UAH data in 2006 to see if there were any errors, I think in recent years the two groups have diverged somewhat, with UAH using data from the Aqua satellite (for instance) in it’s TLT product, and RSS using that data for separate ocean products:
http://www.remss.com/amsr/amsr_data_description.html
I’d have to look into this.
Back over at UAH we find the descriptor “14,000 ft / 4.4 km / 600 mb (ch05).
Maybe you shouldn’t rely on a “DISCOVER” page intended for high school and college students for the source of your understanding of UAH data. Try here:
http://www.ncdc.noaa.gov/oa/climate/research/uah-msu.pdf

Two deep-layer tropospheric temperature products, one for the lower troposphere (T2LT surface to about 8 km) and one for the midtroposphere (T2 surface to about15 km, thus including some stratospheric emissions), are based on the observations of channel 2 of the MSU

This is also useful:
http://vortex.nsstc.uah.edu/data/msu/t2lt/readme.13Apr2010
“Lower troposphere” is surface to 8 km (5 miles) – the same definition applies to RSS, UAH and UW:
http://www.ncdc.noaa.gov/sotc/?report=global
Don’t think you “caught” RSS in some “trick”.
Your UAH “Discover” page can break down layers of atmosphere however they want, but “lower troposphere” includes their “near surface layer”, 4.4 km, and 7.5 km layers.
BTW, it takes a lot of processing to try and figure out the temperature for a specific layer in the atmosphere:

http://en.wikipedia.org/wiki/Satellite_temperature_measurements
Satellites do not measure temperature as such. They measure radiances in various wavelength bands, which must then be mathematically inverted to obtain indirect inferences of temperature. The resulting temperature profiles depend on details of the methods that are used to obtain temperatures from radiances. As a result, different groups that have analyzed the satellite data to calculate temperature trends have obtained a range of values. Among these groups are Remote Sensing Systems (RSS) and the University of Alabama in Huntsville (UAH). Furthermore the satellite series is not fully homogeneous – it is constructed from a series of satellites with similar but not identical instrumentation. The sensors are subject to fade over time, and corrections are necessary for satellite drift in orbit. Particularly large differences between reconstructed temperature series occur at the few times when there is little temporal overlap between successive satellites, making intercalibration difficult.

Note the following quirk, TLT extends from 70S to 82.5N…
That’s a good observation – I think the microwave sounding units have too much interference from the Antarctic ice sheet to reliably get temperatures for the air mass above it. I’m pretty sure UAH also covers 70S to 82.5N, although they don’t break down latitudes in their data files, preferring to use descriptions like “NoPol”.
http://en.wikipedia.org/wiki/Advanced_Microwave_Sounding_Unit
I know “NoPol” is not up to 90N:
http://wattsupwiththat.com/2008/03/08/putting-a-myth-about-uah-and-rss-satellite-data-to-rest/

UPDATE: An additional question has been brought up related to why the data seems to be missing from the poles. Dr. Christy also responded:
As the spacecraft rolls over the pole it does so at an inclined orbit so that the highest nadir latitude is about 82 deg with the scanner looking out a bit closer to the pole. Since we apply the scan line data mostly to the nadir area directly below the satellite, the actual data only go to about 83 deg. In the gridded data I interpolate over the pole, but I wouldn’t trust the data too much beyond 85 deg.

Huh, interpolating over the Arctic – doesn’t Dr. Hansen do something like that ?
Perhaps Dr. Spencer can enlighten us on UAH lower troposphere temperature anomaly coverage over Antarctica. Does the ice sheet interfere with the MSU and AMSU instruments too much, or does UAH do some different processing than RSS for data over Antarctica ?