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Post by dwerth on Dec 3, 2009 8:53:39 GMT
I have been staring at the link below for a while, and I am having a hard time reconciling the two plots. www.woodfortrees.org/plot/uah/mean:12/plot/gistemp/mean:12Why the massive difference in the two plots? It seems that we are averaging two tenths of a degree difference in the anomaly during the period when we have both data sets. That is a very large divergence when you are talking about a total variance of ~.8C over 130 years. Granted, we have only 30 years of satellite data, but that will grow over time (obviously). In addition, this divergence seems to be widening, though that could be a trick of the eye. Thoughts? *edit for silly url linkage fun |
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Post by hairball on Dec 3, 2009 9:16:22 GMT
GIST starts earlier, so its anomaly is from a colder baseline.
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Post by glc on Dec 3, 2009 9:22:52 GMT
Why the massive difference in the two plots? It seems that we are averaging two tenths of a degree difference in the anomaly during the period when we have both data sets. That is a very large divergence when you are talking about a total variance of ~.8C over 130 years. Granted, we have only 30 years of satellite data, but that will grow over time (obviously). In addition, this divergence seems to be widening, though that could be a trick of the eye.
Thoughts?
The difference of "two tenths of a degree difference" is due to the fact that UAH uses a different base period to GISS. GISS use the 1951-1980 period to calculate anomalies while UAH use the 1979-1998 period.
Because, 1979-1998 was warmer than 1951-1980, it ought to be obvious that temperature anomalies using the former will be lower than using the latter.
Although, I say I should be obvious it clearly isn't obvious to many people as this misunderstanding comes up time and time again, so let's look at a simple example.
The average GISS anomaly for 1951-1980 should, in theory, be ZERO. If 2009 is +0.5 deg warmer than the average 1951-1980 temperatures then the average anomaly for 2009 would be +0.5. But the average temperatures for 1979-1998 are +0.2 deg warmer than the 1951-1980 average temperatures, so 2009 is only +0.3 deg warmer than 1979-1998.
If GISS used the same base period as UAH (i.e. 1979-1998) the the GISS anomaly for 2009 would be +0.3 which would be much closer to the UAH anomaly.
Whether any divergnce is taking place is a separate issue but I don't believe there is any significant divergence.
..... of course I could have just said what hairball said but he hadn't posted at the time I was composing my little lecture.
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Post by dwerth on Dec 3, 2009 9:33:15 GMT
Doh, right. Thanks, I forgot about the different time when the sequeces were at "zero."
Thanks GLC
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Post by hairball on Dec 3, 2009 9:45:06 GMT
Hah, no worries glc; they're both bs in any case as far as I'm concerned if that helps  |
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Post by poitsplace on Dec 3, 2009 11:37:58 GMT
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Post by hilbert on Dec 3, 2009 14:27:44 GMT
"It surely is cold, Dad."
"Son, when I was your age, it was a lot colder--in fact, just this week, we realized that it needed to be even colder than I remembered."
:-)
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Post by magellan on Dec 3, 2009 17:39:35 GMT
Why the massive difference in the two plots? It seems that we are averaging two tenths of a degree difference in the anomaly during the period when we have both data sets. That is a very large divergence when you are talking about a total variance of ~.8C over 130 years. Granted, we have only 30 years of satellite data, but that will grow over time (obviously). In addition, this divergence seems to be widening, though that could be a trick of the eye.
Thoughts?The difference of " two tenths of a degree difference" is due to the fact that UAH uses a different base period to GISS. GISS use the 1951-1980 period to calculate anomalies while UAH use the 1979-1998 period. Because, 1979-1998 was warmer than 1951-1980, it ought to be obvious that temperature anomalies using the former will be lower than using the latter. Although, I say I should be obvious it clearly isn't obvious to many people as this misunderstanding comes up time and time again, so let's look at a simple example. The average GISS anomaly for 1951-1980 should, in theory, be ZERO. If 2009 is +0.5 deg warmer than the average 1951-1980 temperatures then the average anomaly for 2009 would be +0.5. But the average temperatures for 1979-1998 are +0.2 deg warmer than the 1951-1980 average temperatures, so 2009 is only +0.3 deg warmer than 1979-1998. If GISS used the same base period as UAH (i.e. 1979-1998) the the GISS anomaly for 2009 would be +0.3 which would be much closer to the UAH anomaly. Whether any divergnce is taking place is a separate issue but I don't believe there is any significant divergence. ..... of course I could have just said what hairball said but he hadn't posted at the time I was composing my little lecture. Whether any divergnce is taking place is a separate issue but I don't believe there is any significant divergence. It's plain to see HadCRUT and UAH are diverging. GISS is much worse. There is a >.1 deg difference in average temp between UAH and HadCRUT since January 2008 alone. How anyone can say there is no significant divergence is puzzling.  |
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Post by steve on Dec 3, 2009 17:55:32 GMT
Anyone who knows anything about UAH should know that the data has been radically corrected numerous times. So it's not that puzzling to think that there might be one or two more errors or uncertainties. Measuring temperatures from satellites is not easy.
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Post by sigurdur on Dec 3, 2009 18:31:40 GMT
Anyone who knows anything about UAH should know that the data has been radically corrected numerous times. So it's not that puzzling to think that there might be one or two more errors or uncertainties. Measuring temperatures from satellites is not easy. I have to agree with Steve on this one. In fact Dr. Christy would also admit to this I believe. Which leads us to the conundrom of..... Are any of the temp data sets capable of showing a .1C change with any validity at all. My answer to this is ....a resounding .......no. Out of the billions of dollars....and yes.......billions of dollars/pounds/yen/ etc spent on climate research, the single biggest failure is that there is NOT an established method of determing temps. One should NOT have such a poor system that there needs to be ANY tricking of the data nor removing of the blips. The lack of doing so only shows the lack of credibility of the science. This is one thing that should not be hidden, nor riddled with fraud, which it has been for decades. |
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Post by dwerth on Dec 3, 2009 18:46:16 GMT
This leads me to pose the question of: does anyone know how large the error bars should be for the UAH data set? I have looked and cannot find a reference to point out how precise it should be.
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Post by smoore on Dec 3, 2009 19:32:53 GMT
Anyone who knows anything about UAH should know that the data has been radically corrected numerous times. So it's not that puzzling to think that there might be one or two more errors or uncertainties. Measuring temperatures from satellites is not easy. I believe GISS and HadCRUt have been changed at times as well. Apparently measuring temperatures from land based stations is not easy either. |
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Post by dwerth on Dec 3, 2009 20:34:16 GMT
Smoore wrote: Well, when you are dealing with the variance that is inherent in, at least the majority of, the US land temperature stations, it is easy to see that the desired accuracy of the measured data may be significantly off. I am unsure as to the method the various data sets use when incorporating this variance into their confidence assesments, but I hope that they err on the side of a wider confidence band than a tighter one, even though it is tempting to use a tighter one from a pride perspective. Stacking tolerances makes me an unhappy person  |
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Post by magellan on Dec 3, 2009 20:54:45 GMT
A simple question:
Without knowing the intricacies, what is most likely to produce more error, one sensor that can be calibrated and corrections are quantifiable/verifiable based on standardized empirical methods or several thousand sensors that are never calibrated from which resulting raw data (refused release of by the gatekeepers of said data) are adjusted ad hoc based on undisclosed methods, are interpolated/extrapolated/manipulated and cannot be verified?
Look up HO83 temperature sensor for starters. This does not include land use change, poor siting and homogenization issues, nor the fact that the network has shrunk in number by a very substantial percentage.
I’ve seen both here and more recently Christopher Monckton state satellite data is or was at some time calibrated to surface data. Nowhere in the literature or from Christy and Spencer can I locate where UAH relied upon surface data for the initialization and calibration of their product. They compare to balloon data but do not adjust to them.
Oh, and for the record, the corrections made to UAH in total are within the margin of error. The diurnal drift issue was resolved several years ago by UAH and they no longer use the NOAA-14/NOAA-15 in favor of the AQUA system. Their daily temp database does not yet reflect this change unfortunately but they were supposed to update it by now.
Me, I'll trust satellite data for this particular metric over surface data any day.
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Post by toughluck on Dec 3, 2009 21:15:29 GMT
Out of the billions of dollars....and yes.......billions of dollars/pounds/yen/ etc spent on climate research, the single biggest failure is that there is NOT an established method of determing temps. Yup its pathetic, that the histeria about global warming increases inverserly to the number of temperature stations in the world. It makes me angry that of all the money spent, little goes to temperature sensing station maintenance, repair and calibration. The raw data from these stations should be in the public domain, something like google code or a wiki so that any one has access to it, and also to bring to light when the data starts to degrade as it has in the last 20 years. ossfoundation.us/projects/environment/global-warming/myths/images/fake-images/nvst.jpg/image_preview |
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