Talk:Satellite temperature measurements

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Step Change?[edit]

See here. Using the UAH and RSS data sets from 1980 to present, apply a linear trend analysis (similar to current chart image in the article). However run the linear trend from 1980 to 1997, then from 1998 to present. Reason -- because of the huge temperature spike attributed to the El Nino in 1998. If you do this, what jumps out of the data set is not a gradual 0.2C degree temperature increase by decade, but instead a huge step change jump. Do you all think this is a valid linear trend analysis compared to the current image linear trend? SunSw0rd (talk) 14:44, 6 February 2011 (UTC)

(Moved from own section to here):

It could be made a lot clearer exactly what the table in this section is supposed to show. It seems to purport to be the global decadal trend since Dec 1978 according to Christy et al. Is that with retrospective corrections or without?

Can anyone explain the jump in the values on the table in this section of the article

1997 0.040

1998 0.112

I know 1998 was hot but to to shift the trend over 20 years that much would take some doing!

IanOfNorwich (talk) 10:06, 26 February 2011 (UTC)

Having seen SunSw0rd's earlier comment on this and following his link, it looks like the table is accurate and the jump is due to the anomaly in 1998 divided by 20 year being large compared to the trend. This is in good agreement with the table although the site uses up-to a given year so all the years differ from the chart by 1.

So the table does seem to correctly illustrate its point. IanOfNorwich (talk) 10:55, 26 February 2011 (UTC)

While on the subject of this section, it would be nice to have a table of the most up to date RSS and UAH decadal trends for each of the channels, how about this:

Channel Start End Date RSS Global Trend (K/decade)[1] UAH Global Trend (K/decade)
TLT 1979 2011-01 0.163 0.140[2]
TMT 1979 2011-01 0.099 0.052[3]
TTS 1987 2011-01 0.008
TLS 1979 2011-01 -0.306 -0.391[4]

I was thinking to add something like this table to the MSU temperature measurements article. As a side note, to avoid confusion with the data in the article, RSS trends updated to version 3.3 are available over the graphs at the end of the page,those at the middle of the page are still the v3.2 trends:
Changes description:
tlt:+0.148 tmt:+0.091 tts:+0.001 --Giorgiogp2 (talk) 21:33, 27 February 2011 (UTC)

Thanks, Giorgiogp2, I was just beginning to scratch my head as I'd seen tlt:+0.148 on the graph there. I'll adjust and add it to the MSU article. I'm for adding it to this page also. If there's room for a list of historic trends of UAH T2LT then there should be room for this.

While on that subject I'd like to see the RSS data in that table as well. If you look at this the change is from about 0.8 to 0.15, which is a similarly sized jump but gives a slightly different impression. (Perhaps that is now different in v3.3?) I don't know if one data set is better than the other, they both seem worthwhile. I can't, however, find that data in that form. Anyone know where the UAH historic global trend averages come from? I can't find it in any nearby ref. IanOfNorwich (talk) 23:59, 27 February 2011 (UTC)

I looked to add it to the MSU article but the data is currently in the lead and nowhere obvious to put it (I won't put a table in the lede). It's too late for me to be restructuring articles right now so it's not there. I have, however, added it to the 'Trends from the record' section. There is room for a table of the latest trends in that section! IanOfNorwich (talk) 00:10, 28 February 2011 (UTC)

Now that it is 2013, go to the original link (here) and you will see the step change even more clearly. I belive this gives a much more accurate perspective of the actual data than does the current image. Also of interest is that the 2 satellite data sets diverge after the break in opposite directions regarding trend. SunSw0rd (talk) 16:19, 30 April 2013 (UTC)

Note also that the step change break is seen clearly in the HadCRUT#HadCRUT3 (sea surface, not satellite) results here. I believe this confirms the logic of showing the trends pre and post break for 1998. SunSw0rd (talk) 16:29, 30 April 2013 (UTC)
(edit conflict) Tamino had a good educational piece last year on how step changes can be both a better fit to the the data, but less significant than a linear trend. Essentially, the lower residuals are offset by the fact that there are more free parameters in the step model. In this particular case, the point of the graph is to show the match in the various surface and satellite records in terms of their overall trends, hence why a linear trend is computed for each. Sailsbystars (talk) 16:31, 30 April 2013 (UTC)
Yes, I see the Tamino article. Of interest perhaps is that he concludes with: "The step-changes model has smaller residuals, but the two-straight-lines model has lower AIC (better model)." Note that his last chart has 2 linear trend lines (not one). He is comparing it to the multi-step line models and concludes that it is superior -- and that it may be for showing clarification. I concur the last chart is best. Note however he did not show a Malacca chart with a single linear trend line -- if he had, I would say the one shown with the 2 trend lines is better (more accurate). SunSw0rd (talk) 16:45, 30 April 2013 (UTC)

See here for an update showing HadCRUT compared to RSS from 1987 to present. Again the break can be seen clearly and you can see why there have been media reports about the lack of warming for the past 15 years. SunSw0rd (talk) 12:06, 1 November 2013 (UTC)

Or see RSS MUS Lower Trop. Global Mean for the past 17 years. SunSw0rd (talk) 15:43, 4 November 2013 (UTC)

UAH link to "UAH satellite temperature dataset"[edit]

I'd changed a link In this sentence "Among these groups are Remote Sensing Systems (RSS) and the University of Alabama in Huntsville (UAH)." to point to UAH satellite temperature dataset rather than University of Alabama in Huntsville. That was reverted by JJ.

I changed it because in the past when I first came to this article I was frustrated because when I clicked that link I got the general UAH wiki page which had and still has nothing on climate science at all and no link to any. This didn't help me. What I wanted (and I imagine most people clicking the link would want) was more information about the data set and/or the people compiling it. That is available now at the UAH satellite temperature dataset, which incidentally has a link to 'University of Alabama in Huntsville' for anyone interested in the general institution instead. --IanOfNorwich (talk) 22:07, 30 March 2011 (UTC)

The sentence starts: "Among these groups...", which previously then referred the RSS and UAH groups. You redirected the second reference to a dataset, which is not a group.
The second reference was problematical as it was, in that it is unlikely the entire UAH was working on this topic, and certainly the "group" should be identified more specifically. (Which would lead more closely to "the people" compiling the data.) But the dataset is not a group. My recommendation would be to do some research and identify the specific group at UAH, and refer to them. - J. Johnson (JJ) (talk) 20:23, 31 March 2011 (UTC)
BTW, I see that the same edit (which I have also reverted) was made at Global warming by User:Simplex1swrhs. Is that you? - J. Johnson (JJ) (talk) 20:48, 31 March 2011 (UTC)
Simplex1swrhs is certainly not me. I have only one account. I resent the suggestion that I have two accounts and would appreciate an apology. I assume that he made the edit for the same reason that I did - it is more useful that way. You can change the sentence to "Among these groups are Remote Sensing Systems (RSS) and the University of Alabama Huntsville Global Hydrology and Climate Center (UAH)" if you want but unless you also want to create an article for the "University of Alabama in Huntsville Global Hydrology and Climate Center" it won't help with this question. Wikilinks are not semantic tokens that change the meaning of a sentence. They just make it easier to quickly move around the encyclopedia and thereby understand one article in light of other connected ones.
--IanOfNorwich (talk) 23:24, 31 March 2011 (UTC)
Hey, cool down! I was just asking. And I don't really care much. I have a feeling Simplex is someone we know, but as long as he (she?) stays out of trouble I don't really care.
I agree that wikilinks are not semantic tokens, but "groups", "UAH", and "dataset" are. And I think it is reasonable to require sentences to be syntactically correct in having agreement of semantic tokens. (Also that "UAH" should link to UAH, not a dataset.)
But let's get past that. Please note: I sympathize with why you changed the link, and I agree it can (should) be improved. I am just saying that this "fix" isn't right. Allow me to make a suggestion: let's replace "UAH" with the particular group at UAH that produced the dataset. (Which I am pretty sure isn't "Global Hydrology and Climate Center" — that's NASA, right?) If they don't have a WP page, well, fine so be it. Or use an external link. (This should also be done at UAH satellite temperature dataset, which should certainly have more detail on who created it.) As to linking to the dataset article, well, you have that further down. Okay? - J. Johnson (JJ) (talk) 22:30, 1 April 2011 (UTC)
According to this [1] the "Global Hydrology and Climate Center" is NASA but is at UAH. Just to be clear that we are on the same page, so to speak, I didn't change the text that appeared on the page only the destination of the link, right?--IanOfNorwich (talk) 18:21, 2 April 2011 (UTC)
That's a start. I see that your link links "UAH" to a paper (grrrr) where Christy's affiliation is given as "ESSC/GHCC" at UAH; I gather that means Earth Systems Science Center. I didn't see any mention of satellite datasets (are they hiding??), but perhaps if you nose around a bit you might find something. - J. Johnson (JJ) (talk) 20:41, 2 April 2011 (UTC)
Well, I've changed the wording. Personally I remain unconvinced that, in this context, linking "University of Alabama Huntsville" to their dataset was a problem, but at least it is still now easy to find further info on the topic, albeit at the cost of some clunkiness. --IanOfNorwich (talk) 19:51, 4 April 2011 (UTC)
Much improved. Particularly the being prepared "at" UAH rather than "by" UAH. I could see being prepared "by GSCC at UAH", but they do seem to be shy about it. - J. Johnson (JJ) (talk) 21:25, 4 April 2011 (UTC)

Ian: Just a suggestion, but your latest edit might be clearer with an insertion like "corrections are necessary for the satellite's orbital drift and decay." - J. Johnson (JJ) (talk) 18:57, 7 April 2011 (UTC)

Ian: your most recent edit seems okay in itself. But it did seem rather furtive, in that you did not mention what you were doing, and it is very similar to the matter previously in issue here. Perhaps you could provide a little more "heads up" in the future? - J. Johnson (JJ) (talk) 20:54, 7 August 2011 (UTC)

OK. Sorry, point taken.--IanOfNorwich (talk) 21:34, 7 August 2011 (UTC)

Update trends[edit]

Where did the data for the recent trend updates come from? The same sources as the previously? Then the access-dates should be updated. Otherwise it looks like they came out of thin air. Which I realize is more or less what the satellites do, but it should be documented. ~ J. Johnson (JJ) (talk) 21:18, 13 February 2012 (UTC)

Comparison Between Satellite Data Sets and Computer Models[edit]

See here. How valid is this? SunSw0rd (talk) 19:39, 8 November 2013 (UTC)

I can't reproduce it myself. I get that there was a dT of 0.5 C whereas Dr. Spencer's graph only shows an increase of 0.1 C. I note that he seems to be comparing only the 20S-20N latitudes, which I don't have an easy way of getting access to. Not sure the reason for why there's such a big change with an extra 20 deg of latitude, (I used 30S-30N) though, although the poles have been warming faster than the rest of the planet.... Sailsbystars (talk) 15:37, 9 November 2013 (UTC)
I suspect that this is closer since it is both the UAH and RSS datasets (not HadCRUT). But he applied "squares" and I don't see how to do that with the Wood For Trees site. Also WFT only provides a data start of 1980 for the satellites even if you set it to 1978. SunSw0rd (talk) 03:08, 10 November 2013 (UTC)

Problem with UAH Data Graph and Current UAH / RSS Data Graph[edit]

See UAH Satellite-Based Temperature of the Global Lower Atmosphere (Version 5.6). Now compare to the graphic labelled "Surface and Satellite Temperatures" on the top right of the page (I don't include the link here because it makes a huge image, just click on current image on page to view). There is a discrepancy between the UAH record in the two graphics. Specifically the current graphic shows UAH (red) having many recorded results between +0.2 to +0.4 between 1980 and 1985. However the UAH graphic posted in the link I provided above shows no correlation to this and only exceeds +0.1 for a single data point in 1983. Looking back and forth between the graphics it appears the current Wikipedia graphic has shifted the UAH data upwards by approximately +0.3 for the years 1980 to 1985. What is the explanation? SunSw0rd (talk) 19:13, 20 December 2013 (UTC)

You mean File:Satellite Temperatures.png? That and your fig don't have the same anomaly base William M. Connolley (talk) 20:21, 20 December 2013 (UTC)
Yes I mean that. Both figures are referencing UAH so -- what is the specific basis for the difference? Since they are referencing UAH data sets -- are the data sets different? Also please note the link below the File:Satellite Temperatures.png figure (UAH 2003; data set tltglhmam version 5.2 with 2009 updates) is broken. What would be the correct link to the UAH anomaly base for the current image? SunSw0rd (talk) 01:04, 21 December 2013 (UTC)

I suggest that this RSS versus UAH graphic is more accurate than File:Satellite Temperatures.png because it correlates directly with File:Radiosonde_Satellite_Surface_Temperature.svg. The existing graphic lower down in the article File:Radiosonde_Satellite_Surface_Temperature.svg more accurately portrays the data specific to the article which is "Satellite temperature measurements". I recommend replacing File:Satellite Temperatures.png with File:Radiosonde_Satellite_Surface_Temperature.svg and then deleting File:Radiosonde_Satellite_Surface_Temperature.svg from its current location in the article. Comments? SunSw0rd (talk) 14:53, 4 January 2014 (UTC)

You haven't understood what I said about different anomaly bases. Until you've worked that out, you've got no business discussing the accuracy of any of these pix William M. Connolley (talk) 17:55, 4 January 2014 (UTC)
O Rly? Because the reference link to the data for the current pic is broken. And the article has a superior pic already lower down the page. Did you ignore? SunSw0rd (talk) 21:47, 4 January 2014 (UTC)