Comments on: Seasonal divergence in tropospheric temperature trends

By: RAJARAM KANE

RAJARAM KANE — Mon, 27 Jul 2009 14:39:50 +0000

I want the time series of annual values of global tropospheric ttemperatures from 1900 up to date. Can you send?

Regards.

R. P. Kane

[DC: Since estimates of global tropospheric temperature are based on analysis of satellite-based sensor records, these values are only available from 1979 on.]

By: Geoff Bell

Geoff Bell — Mon, 20 Jul 2009 13:04:22 +0000

Speaking as a very old and old fashioned Physical Chemist I am astonished that anybody can expect to obtain any meaningful measurements of “mean global temperatures”, especially when they are apparently being measured to a tolerance of, say, +/- 0.o1C, in a totally chaotic climate syystem where the actual surface temperatures at any time can vary from, say, -45C to +45C. Any data obtained must be so suspect as to be totally meaningless.

By: UAH annual cycle continues in 2009 « Deep Climate

UAH annual cycle continues in 2009 « Deep Climate — Fri, 05 Jun 2009 06:20:00 +0000

[...] of this temperature series. For more on the UAH annual cycle see my previous posts on the topic (part 1 here and part 2 [...]

By: lucia

lucia — Sun, 15 Mar 2009 11:50:21 +0000

Hi–
UAH – June vs Dec definitely looks like a mismatch which is troubling. But, it would be useful to add uncertainty intervals just so we can see. (By eyeball, I expect them not to match. But it’s still worth checking.)

[The CIs are quite wide - the unadjusted standard error is on the order of 0.2 deg. C per decade. But that's not the whole story.

These diverging trends are a symptom of an annual cycle in UAH which has a remarkably coherent effect, peaking early in the year, descending smoothly to a trough around May/June and back up through remaining months.

Widely diverging trends with random spikiness would be troubling enough (even if technically they were within the uncertainty bounds). But the smooth annual progression, as evidenced in the strong peak in the 12-month cycle in the Fourier power spectrum for recent years' data, and in the resulting pattern of monthly trends I have noted, makes it clear that something is seriously amiss here.]

By: Eli Rabett

Eli Rabett — Sat, 07 Mar 2009 20:48:16 +0000

To the eye, the major differences appear to start ~1999, concurrent with the launch of the AMSU. The difference could be how the AMSU and MSU data were merged. The last MSU failed ~2004. Also FWIW things like your graph of the big difference between UAH and RSS over the annual cycles look like two sinusoidal oscillations moving in and out of resonance. [Response: Eli, thanks for coming by (and being the first to comment). It does seem that the major divergence starts after the launch of NOAA-15 (in May, 1998 I think). But there may be more to it than that. One problem with UAH LT is that the data changes quite a lot within the same version (which has been 5.2 since 2005). This is possibly related at least in part to the inclusion of the AMSU on the AQUA satellite since early 2008, with data merged with NOAA-15 back to 2002 (see the UAH readme file). Now it turns out that NOAA-15 is no longer even being used at all, according to Roy Spencer's website:
The biggest adjustment is the fact that we don’t even use NOAA-15 right now…we are using the AMSU data from NASA’s Aqua satellite in the final UAH product.
I guess they they forgot to update the LT 5.2 Readme. But it turns out that the differences in raw data since 2002 are much more substantial than I thought, since RSS does not use AQUA at all, apparently. I haven't seen this discussed very much ... I feel another post coming on.]