Comments on: Station Homogenization as a Statistical Procedure

By: laterite

laterite — Mon, 06 May 2013 06:07:23 +0000

This venom from Victor Venema may be worth commenting on.

By: James Ringo

James Ringo — Mon, 23 Jul 2012 19:12:12 +0000

PHA = predecessor homogenization algorithm Obvious to me only after it’s obvious. Did not find it in acronym link

By: Weekly Climate and Energy News Roundup | Watts Up With That?

Weekly Climate and Energy News Roundup | Watts Up With That? — Sun, 22 Jul 2012 23:49:47 +0000

[...] http://climateaudit.org/2012/07/17/station-homogenization-as-a-statistical-procedure/ [...]

By: vvenema

vvenema — Sat, 21 Jul 2012 18:08:26 +0000

Don, did you read the articles? Or is this just an example of your open-mindedness as a sceptic? (And well written articles often contain the most (small) mistakes. If the language is a bit difficult to understand this stimulates the reviewer to think more. Thus this combination would actually fit your prejudices.)

I can give you some other papers. How do you like these?

From a time before man-made climate change:
Margary, I.D., 1924. A comparison of forty years’ observations of maximum and minimum temperatures as recorded in both screens at Camden Square, London. Q.J.R. Meteorol. Soc., 50:209-226 and 363.

Marriott, W., 1879. Thermometer exposure — wall versus Stevenson screens. QJ.R. Meteorol. Soc., 5:217-221.

Or from a reliable Dutchman:
Brandsma, Theo. Parallel air temperature measurements at the KNMI-terrain in De Bilt (the Netherlands) May 2003-April 2005, Interim report, 2004. http://wap.knmi.nl/onderzk/klimscen/papers/Hisklim7.pdf

Van der Meulen, J.P. and T. Brandsma. Thermometer screen intercomparison in De Bilt (The Netherlands), Part I: Understanding the weather-dependent temperature differences) Int. J. Climatol, 28, pp. 371-387, doi: 10.1002/joc.1531, 2008.

Or from a reliable Norwegian guy:
Nordli, P. Ø. et al. The effect of radiation screens on Nordic time series of mean temperature. International Journal of Climatology 17(15), doi: 10.1002/(SICI)1097-0088(199712)17:153.0.CO;2-D, pp. 1667-1681, 1997.

I did not read all of these papers yet, but I guess the titles are already sufficient to disproof the original claim that there are no parallel measurements to validate the breaks found during homogenization. It is just not the kind of literature that makes it into Science, Nature or the New York Times. Luckily some colleagues still do it because it is important work.

By: Jeff Norman

Jeff Norman — Sat, 21 Jul 2012 14:53:41 +0000

[quote]Unfortunately, there are very very few records without gaps or changes in location/instruments/time of data collection over 100 yrs. That is why you need to homogenize.[/quote]
Actually this was one of my very first clues that the IPCC had little to do with Climate and everything to do with Change. If they truly cared about climate back in 1990, AR1 would have recommended funding for upgrading climate monitoring systems in areas of the world where data was lacking. It would have identified uncertainties in the available data and funded research into improving the uncertainties. This silence was continued in 1995 etc.

By: Don Keiller

Don Keiller — Sat, 21 Jul 2012 12:15:52 +0000

@vvenema
In my experience “Well written” and “P.D. Jones” are unlikely bedfellows.

By: Steven Mosher

Steven Mosher — Sat, 21 Jul 2012 01:15:10 +0000

Its easy to test whether that Potential source of error, is in fact a source of error. dont use RSM. and dont homogenize.

answer doesnt change.

By: E.M.Smith

E.M.Smith — Fri, 20 Jul 2012 23:55:35 +0000

Still working through all the comments… but one thing I’d like to see explored in the adjustment and homogenizing processes is how they deal with 60 year cyclical weather regime changes.

During cold phase of the PDO, for example, the jet stream is more loopy (deeper Rossby Waves) while during the warm phase they are more ‘zonal’. This means there can be a rapid and pervasive shift of the relationship between a station and it’s “neighbors” (as The Reference Station Method lets them be up to 1200 km away). So a relationship is established in one 30 year period, then can be applied in a period with dramatically different relationship (per what I’ve seen in the GIStemp code).

IMHO, that is a major potential source of error.

Right now the West Coast of the USA is having a quite cold time, while the East Coast is hot (all due to deep Rossby Waves of opposite direction, unlike in the prior warm phase of the PDO). Similarly, England is wet and cold while over in Russia hot air is headed to the N. Pole to dump its heat. Relationships changed…

So IMHO any statistical method to find “changepoints” also has to be able to allow for a periodic sudden break in relationship that is in fact quite valid. From what I’ve seen, the methods used do not address this point.

By: SteveSadlov

SteveSadlov — Fri, 20 Jul 2012 16:48:05 +0000

Heads up. Even though this site does not appear to run ads a Russian “ad server” is somehow interacting with this site and attempting to establish contact with the servers (and maybe even clients?) of those accessing this site.

By: SteveSadlov

SteveSadlov — Fri, 20 Jul 2012 16:45:19 +0000

I wonder if I’d be allowed to cook … er … um … sorry … keep my books using a similar approach?