Category Archives: Steig at al 2009

AR4 Models and the Ross Sea

I noticed something interesting in AR4 about Antarctic models, that no one mentioned in the initial commentary on Steig et al. When Steig et al 2009 came out, commenters had some fun teasing the clergy over at realclimate over Spencer Weart’s article the prior year. Pielke Jr Lucia CA Speaking for myself, I went to […]

Downloading UWisc Data

The Jeffs have been exploring the UWisc AVHRR data which is stored as a lot of gzipped ncdf files. I couldn’t figure out how to download and open this data into R. So, as I usually do in these cases, I asked CA reader Nicholas who, as usual, has a solution. I edited this slightly […]

Steig’s Secret Data

I checked in at Steig’s webpage to see if the long-awaited AVHRR had finally materialized. Update (Mar 26, 2009 aa am Eastern) This is now released. It had the following new paragraph (without any change notice to show that this dataset had not been there from time immemorial): cloudmaskedAVHRR.txt contains the monthly-averaged cloud-masked satellite data […]

Steig Mystery (almost) Solved!

Thanks to some insight from Ryan O (#43), we have been able to make progress on the puzzle of where the values in the Steig paper came from. In fact, it now is quite apparent that Steig et al used the reconstructions based on the AVHHR satellite data rather than the ones based on the […]

Its a Mystery!

Ok, coffee break’s over, back on your heads! Let’s get back to business here… I like puzzles. They provide no end of intellectual entertainment – and there is a thrill with figuring out the solution, particularly if the solution is done in a particularly elegant fashion. A good source of puzzles seems to be climate […]

Gavin and the PC Stories

How many principal components to retain? Recent readers of Climate Audit may not realize that this was an absolute battleground issue of MBH and Wahl and Ammann. In one sense, it was never resolved with MBH back in 2003-2005, but that was before the existence of blogs made it possible to focus attention on problems. […]

Steig 2009’s Non-Correction for Serial Correlation

In a story featured on the cover of Nature, Eric J. Steig, David P. Schneider, Scott D. Rutherford, Michael E. Mann, Josefino C. Comiso and Drew T. Shindell report to have found “significant warming” that “extends well beyond the Antarctic Peninsula to cover most of West Antarctica, an area of warming much larger than previously […]

Buell: ‘Castles in the Clouds’

CA reader hfl, who cited Buell’s documentation of the dependence of principal component patterns on shapes, has sent me a scanned pdf version now available here. It concludes by observing that analyses that fail to consider this phenomenon (and there is ample evidence that Steig et al falls into this category) “may well be scientific […]

Steig Eigenvectors and Chladni Patterns #2

Yesterday, I showed an interesting comparison between the 3 Steig eigenvectors and “Chladni patterns” generated by performing principal components on a grid of spatially autocorrelated sites on a disk. Today I’ll show a similar analysis, but this time using a random sample of points from actual Antarctica. The results are pretty interesting, to say the […]

Steig Eigenvectors and Chladni Patterns

Last year, I did a few posts connecting spatial autocorrelation to something as mundane as the Stahle/SWM tree ring network. In the process, I observed something that I found quite interesting – that principal components applied to geometric shapes with spatially autocorrelated series generated Chladni patterns, familiar from violins and sounds. The Antarctica vortex represents […]