Tag Archives: UAH

Rapidly warming satellite data sends “skeptics” scurrying to models

Most people remotely familiar with climate “skeptics” know that if you can count on them for anything, it’s the following:

  1. “Skeptics” love satellite temperature data.
  2. “Skeptics” hate computer models. 

“Skeptics” claim to reject the surface instrumental temperature record because of alleged biases in the data, supposedly fraudulent “adjustments”, etc. These objections are not based in reality, as multiple analyses of the surface data have shown. In reality, “skeptics” reject the surface instrumental record for the same reason they reject so much of modern science: it doesn’t show what they want it to.

“Skeptics” claim that satellite temperature data, derived from microwave brightness soundings of the lower troposphere, are superior. The reality is that the satellite data cover a shorter record (and thus capture less of the warming), use a more recent baseline (and thus have cooler “anomalies” relative to the surface record), and are more sensitive to natural climatic variability like ENSO (and thus make the human signal harder to pick out visually). In other words, they like the satellite data because they show them more of what they want to see, and less of what they don’t. That one of the groups producing a satellite record is comprised of Roy Spencer and John Christy is icing on the cake.

And if there’s one thing “skeptics” disdain more than the surface instrumental record, it’s computer models. The ostensible justifications are legion, but the underlying cause is simple: they show things that “skeptics” don’t want to see.

So it was with great amusement that I took note of the “skeptic” reaction to the UAH satellite record’s rapid January warming, which reached temperatures exceeded only during the strong El Niño years of 1998 and 2010:

Rather than accept their beloved satellite data at face value, “skeptics” cast about for any alternative data set that didn’t show the inconvenient warming. Over at the wretched hive of scum and villainy known as WUWT, the innumerate and oft-beclowned Anthony Watts seized upon NCEP data showing much less January warming:

Of course NCEP isn’t actually an observational data set. It’s a reanalysis product created by those evil and untrustworthy models. You know, the ones “skeptics” demonize regularly in outlets like WUWT:

When the satellites don’t show what they want to see, “skeptics” waste no time in fleeing to the models they otherwise disdain.

Because climate “skeptics” are anything but skeptical.

And just for the record, the RSS satellite record showed a similarly large (+0.341°C) increase in January 2013.

Common sense gets Rogered

Roger Pielke Sr. has spent the past few days casting about for anything to which he can latch onto in hopes of promoting an upcoming paper that supposedly shows how terrible the surface instrumental record is.

On Tuesday, he wrote about an image from NOAA using the GHCN surface data (which shows May as quite a warm month) and then shows an image using UAH to claim that the differences between the two show that the GHCN surface data are biased warm:

The above figure shows a picture of warmer than average land surface temperatures almost everywhere. This image is from the NOAA report…

While the lower tropospheric data shows a very warm May, it is not as anomalous as at the surface as diagnosed by the Global Historical Climatology Network. The spatial map of lower tropospheric temperatures for May 2012 is shown below

In this data, May 2012 has a global composite lower tropospheric temperature anomaly of +0.29 C (about 0.52 degrees Fahrenheit) above 30-year average for May. The NOAA plot above has a global composite of “more than 1°F above the 20th century average” according to the NOAA article.

3. This divergence between the surface temperature analysis and the lower tropospheric temperature analyses is further demonstration of the divergence between these two data sets as we reported on in [lengthy onanistic bout of self-citation follows].

Today, Roger does much the same by comparing the NOAA/GHCN May 2012 image to an image generated using NASA MODIS land data:

It does not take a quantitative analysis to see regions of large differences, such as the cool anomalies in the NASA data in Africa, Scandinavia, and elsewhere. While they are not measuring the same temperatures, the anomalies should be quite similar {For the GHCN, NOAA NCDC uses air temperature measurements which are supposed to be 2m above the ground; they also use the mean temperature anomalies which are computed using maximum and minimum temperatures}.

The areal coverage of the temperature anomalies, however, are not the same. The NOAA analysis shows much larger areas of warmer than average surface temperatures than seen in the NASA NEO analysis.

Presumably some of you have seen where Roger’s gone wrong immediately. Congratulations, because Roger obviously still hasn’t. Note what he compares in the first set of images:

In this data, May 2012 has a global composite lower tropospheric temperature anomaly of +0.29 C (about 0.52 degrees Fahrenheit) above 30-year average [i.e. 1981-2010] for May. The NOAA plot above has a global composite of “more than 1°F above the 20th century average” according to the NOAA article.

And in the second:

Today, I present at the top of this post the May 2012 surface temperature anomaly analysis from NASA’s Earth Observations program.

As written on the NASA’s Earth Observations program website

Land surface temperature is how hot or cold the ground feels to the touch. An anomaly is when something is different from average. These maps show where Earth’s surface was warmer or cooler in the daytime than the average temperatures for the same week or month from 2001-2010. So, a land surface temperature anomaly map for May 2002 shows how that month’s average temperature was different from the average temperature for all Mays between 2001 and 2010.

Roger’s entire premise is that there is a significant difference between the GHCN surface data used by NOAA, GISTEMP, HadCRUT, and others versus satellite data, and that this demonstrates that the surface data are biased warm. But Roger has completely failed to do the most cursory step of making such a comparison- looking at those data in reference to a common baseline.

Obviously, temperature anomalies relative to the 1901-2000 average are going to appear warmer than anomalies relative to a 1981-2010 baseline.

Obviously, temperature anomalies relative to a 2001-2010 baseline (a timescale in which short-term fluctuations like ENSO are much more significant than over 30 or 100 years) are going to be different in both magnitude and spatial structure.

For something a little more apples-to-apples, how do the size of the UAH satellite and GHCN-based surface anomalies compare?

It turns out that for Roger’s month of interest (May 2012), the UAH temperature is actually warmer than NOAA (and basically identical to GISTEMP):

Is the spatial pattern of the GHCN data really so different than that viewed by MODIS?

Northeastern Atlantic cooling (which becomes even more pronounced using a smaller interpolation length), cooling over much of Africa, cooling over the Pacific Northwest, cooling over Central America, much of Australia, much of Antarctica, etc. are all apparent in the GHCN-based GISTEMP land data when you bother to use the same baseline:


Identical? No, but even Roger admits they’re not measuring the same things exactly. But simply using the same baseline shows that the spatial structure of the temp anomalies is in much closer agreement than Roger would like you to believe.

Is the surface instrumental record biased warm? It’s possible- though many independent evaluations have failed to bear this out. When you hear someone say “It does not take a quantitative analysis to see…” particularly someone with such a lengthy history of cherry picking and apples to oranges comparisons as Roger*, it’s a good time to get… well, skeptical.

*Some examples can be seen herehere, here, here, here, here, here, here, here, etc.

UPDATE: Thanks to Marco in comments, forgot about some gems at Tamino’s here, here, here, etc.

Single realizations vs. means of ensemble projections

[h/t Quark Soup via AFTIC]

Marlo Lewis of CEI (yes, again) writing over at Planet Gore has a post purporting that not only has there been “no warming in the 21st century” (all ~8 years of it? Gosh!), but that “no climate model predicted it”. His evidence is an abysmal graphic allegedly provided to him by John Christy (who along with Roy Spencer produces UAH’s MSU troposphere temperature record):

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