Friday, March 30, 2012

Predicting the UAH Anomaly

I was going to write about this month's raw satellite temperature measurements for the lower troposphere from UAH, and "predict" what the final anomaly for March would be. But I thought I'd better check something first.

At first glance, March seems to be warming up more than recent years, based on the raw data:

So you might say, sure, La Nina is nearly over and we expect apparent global warming to resume again and so on. But then I made this graph of the monthly averages for the raw UAH temperatures, versus that after all the adjustments for satellite drift, etc.:

which shows no correlation. You might think, well, maybe there's some correlation in there, which changes after they do some special adjustment every 1.5 to 2 years:

but that's just too much guesswork. So UAH really means their caveat at the bottom of the page:
The global-average data displayed on this page have only limited quality control, can undergo unannounced changes, and so should only be used as a general guide. Official, quality-controlled global lower-tropospheric temperatures, using more extensive processing procedures (and possibly different satellite instruments) are updated every month and are available at:
So, with the understanding this is for entertainment purposes only (as they say), my prediction guess for the March LT anomaly is:

UAH global LT March anomaly = +0.12°C

Be sure to read this post by Roy Spencer, which explains some of the complications.


thefordprefect said...

I've been logging the "discover" data for a time and did this post some time ago:

Spencer says the discover page is virtually worthless:

Roy W. SpencerDec 21, 2011 03:59 PM

If you would have read the disclaimer at the Discover website, you would have realized you can't compare the daily, automated, quick-and-dirty data averages there with the fully intercalibrated, quality-controlled UAH dataset that we update every month.

The Discover website data are meant to give a rough idea of how the latest month is shaping up compared to the same calendar month a year earlier, that's all.

To which I replied
thefordprefectDec 25, 2011 05:54 AM

Roy The data is a couple of degrees adrift from satellite to satellite. This is not good! Why bother even giving the data if it so far out to be worthless?

Although there is a statement ofn the discover page about accuracy it says nothing about adjustments. It says nothing about where similar but corrected data can be obtained.

All-in-all this is a poor answer to my criticisms.

If you can correct one series from sattelites , why not all. Or are the corrections too complex for a computer!!!

Please give a link to the adjustments made and data for similar altitudes that are approved by yourselves.


How can AMSU data be better from the same data?

Does Spencer, or one of his minions, individually fettle the data by hand? If a computer is used then why cannot the same corrections be applied to the "discover" data?

David Appell said...

Ford: Interesting link, thanks.

I don't think for a second that UAH (or anyone) fiddles the data. I think they adjust it as best then can. Satellites drift, for one thing, in a way that isn't predicatable. One such factor are solar storms that temporarily expand the atmosphere, which creates drag.

thefordprefect said...


Fettle does not necessarily imply falsifying.

I used the term to suggest correction of data by some undisclosed amd manual means.

If the discover data were adjusted the same way (alorythmically - how the height of satellite has changed, atmospheric changes etc.) there would be no problem!