Saturday, December 12, 2015

Satellites vs Thermometers

Sometimes you have to wonder why someone on the science reality side hasn't graphed something earlier.

For the last couple of years, I guess, the climate change denialists have moved from following Roy Spencer's UAH satellite temperature graph to the one by RSS, because of the lower trend it now gives for recent atmospheric warming.   As can be seen from the Skeptical Science trend calculator, this is what your get for RSS for the last 18 years:

This is what you get when you use UAH for the same period:

So you can guess which one is now Andrew Bolt's favourite (even though he used to post only UAH every month.)

But, as people who read other than denialist propaganda know, the satellite method of determining temperatures is inherently complicated, and is about the temperature at different levels of the atmosphere.   Hence, they do compare what they are doing with the balloon based thermometer readings to see if the methods they are using for the satellites seem right.

So, given that RSS is now the denier's outlier, Tamino has graphed it against the balloon thermometer record known as RATPAC, and shows this:

 As Tamino says:
They’re in excellent agreement until recently. Lately there’s a strong divergence, one which seems to be growing, after about 2012. It’s hard to believe that the problem is with balloon data; yes there are important calibration issues with them, but thermometers are still thermometers, and there are just as many serious issues if not more with the satellites’ microwave sounding units, including merging over a dozen different instruments, disentangling the signal from different levels of the atmosphere, and changing orbital drift and timing — issues about which different teams do not agree.....
 The RSS data simply fail to show the recent warming which is plain to see in the balloon data — the data from actual thermometers.
Now, as we know from Andrew Bolt's recent whiny post about being called out by Waleed Aly, Carl Mears from RSS is no AGW skeptic.  So I am curious as to why this discrepancy hasn't been brought up earlier.

Unless Tamino has made some sort of mistake, this graph of his absolutely blows away the "satellite temperatures are the gold standard that NOAA is ignoring"  in a way that is so plain to see, even to denialists. (And that's before the likely spike from the El Nino shows up early next year.)

Update:  this recent article in Forbes gave some of the technical details of how satellite measurements work.

1 comment:

IskurBlast said...

Thermometers are thermometers? No thermometers are something we use to infer temperature. The satellites are just as much a thermometers as an old mercury thermometer. They measure one thing and us it to infer temperature.