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Post by walterdnes on May 4, 2009 4:32:19 GMT
RSS is +0.202 This month, I demonstrated my one point of superiority over the UK Met Office... I know when to give up ;D I did not predict April RSS temps based simply on my regression. The projection was +0.250 Instead, I decided to wait until the RSS data came out, and adjust the other 3 predictions based on the adjustment for RSS. So now let's look at the raw regressions, and correct the other 3 temps based on RSS. Raw regressions - RSS projected 0.250; slope 1.024; 0.048 too high
- UAH projected 0.202; slope 1.222
- GISS projected 0.55; slope 0.634
- Hadley projected 0.405; slope 0.480
So my adjusted forecasts are... - UAH = 0.202 - 0.048 * 1.222 / 1.024 = 0.145
- GISS = 0.50 - 0.048 * 0.634 / 1.024 = 0.47
- Hadley = 0.405 - 0.048 * 0.480 / 1.024 = 0.383
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Post by neilhamp on May 4, 2009 18:34:38 GMT
At the risk of introducing last month's debate The running mean UAH data for the first 4 months of each year
1998 0.66 1999 0.13* 2000 0.01* 2001 0.19* 2002 0.37 2003 0.33 2004 0.36 2005 0.42 2006 0.33 2007 0.42 2008 0.02* 2009 0.24 So far, 2009 cooler than 6 out of the last 7 years 0.13 degrees below the 2002/7 mean
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Post by zer0th on May 5, 2009 13:57:59 GMT
UAH: 0.091 Once again there is a rather large discrepancy between our monthly anomaly (+0.09 deg. C.) and that produced by Remote Sensing Systems (RSS, +0.20 deg. C). We (John Christy and I) believe the difference is due to some combination of three factors:
1) we calculate the anomalies from a wider latitude band, 84S to 84N whereas RSS stops at 70S, and Antarctica was cooler than average in April (so UAH picks it up).
2) The monthly anomaly is relative to the 1979-1998 base period, which for RSS had a colder mean period relative to April 2009 (i.e. their early Aprils in the 1979-1998 period were colder than ours.)
3) RSS is still using a NOAA satellite whose orbit continues to decay, leading to a sizeable diurnal drift adjustment. We are using AMSU data from only NASA’s Aqua satellite, whose orbit is maintained, and so no diurnal drift adjustment is needed. The largest diurnal effects occur during Northern Hemisphere spring, and I personally believe this is the largest contributor to the discrepancy between UAH and RSS.
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Post by glc on May 5, 2009 14:51:32 GMT
Re: UAH anomaly
Roy Spencer's explanation is reasonable except that the raw AMSU temperatures don't suggest an anomaly as low as +0.09.
Walterdnes:
I reckon you might be right - it's time to give up.
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Post by woodstove on May 5, 2009 15:58:15 GMT
Re: UAH anomaly Roy Spencer's explanation is reasonable except that the raw AMSU temperatures don't suggest an anomaly as low as +0.09. Walterdnes: I reckon you might be right - it's time to give up. Walter: I disagree with glc, twice. First, your efforts are interesting, and there's no reason that you would work something so complex out in a short period of time. Second, I doubt that Roy Spencer and John Christy have made any significant math errors. Interesting that glc gets upset when giss is accused of fudging the books toward hot but appears quite comfortable alleging bad math on the part of UAH when it comes to cold.
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Post by tacoman25 on May 5, 2009 18:57:01 GMT
Re: UAH anomaly Roy Spencer's explanation is reasonable except that the raw AMSU temperatures don't suggest an anomaly as low as +0.09. Walterdnes: I reckon you might be right - it's time to give up. Don't be hypocritical, glc. You were more than happy to accept UAH's numbers in Jan/Feb, but now you say they don't add up. Second coldest UAH April since 1999 (after last year). 2009 is now running easily cooler than any other year since 2001. 2006, the closest ENSO match to 2009, was running .33 at this time. 2009 is at .24.
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Post by glc on May 5, 2009 19:49:50 GMT
Don't be hypocritical, glc. You were more than happy to accept UAH's numbers in Jan/Feb, but now you say they don't add up. I'm not being hypocritical. I'm just making the point the April anomaly doesn't tally with the raw AMSU temperatures. Walterdnes who has often been quite close with his estimates had predicted an anomaly of +0.25 which is quite a big difference. I'm not the only one who thinks it a bit odd see the comment by Sven (07:04:18) on WUWT here wattsupwiththat.com/2009/05/04/natgeo-sun-oddly-quiet-hints-at-next-little-ice-age/Obviously, there is a part of data analysis process which some of us don't understand. Interesting that glc gets upset when giss is accused of fudging the books toward hot but appears quite comfortable alleging bad math on the part of UAH when it comes to cold. I don't think anyone is "fudging the books" and I did not accuse UAH of bad maths (english) , but I can normally see a possible reason for discrepancies in data. At the moment I'm a bit flummoxed because the raw data suggests an anomaly of somewhere between +0.15 and +0.25. But I don't know exactly what channel data is used or what weightings (if any) are used, so there could easily be a factor that I (and others) have not considered.
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Post by magellan on May 5, 2009 21:57:42 GMT
Don't be hypocritical, glc. You were more than happy to accept UAH's numbers in Jan/Feb, but now you say they don't add up. I'm not being hypocritical. I'm just making the point the April anomaly doesn't tally with the raw AMSU temperatures. Walterdnes who has often been quite close with his estimates had predicted an anomaly of +0.25 which is quite a big difference. I'm not the only one who thinks it a bit odd see the comment by Sven (07:04:18) on WUWT here wattsupwiththat.com/2009/05/04/natgeo-sun-oddly-quiet-hints-at-next-little-ice-age/Obviously, there is a part of data analysis process which some of us don't understand. Interesting that glc gets upset when giss is accused of fudging the books toward hot but appears quite comfortable alleging bad math on the part of UAH when it comes to cold. I don't think anyone is "fudging the books" and I did not accuse UAH of bad maths (english) , but I can normally see a possible reason for discrepancies in data. At the moment I'm a bit flummoxed because the raw data suggests an anomaly of somewhere between +0.15 and +0.25. But I don't know exactly what channel data is used or what weightings (if any) are used, so there could easily be a factor that I (and others) have not considered. You were perfectly content with UAH in January-March. ;D Look at NH data. Remember the SSW? It's gone.
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Post by tacoman25 on May 5, 2009 22:27:02 GMT
Don't be hypocritical, glc. You were more than happy to accept UAH's numbers in Jan/Feb, but now you say they don't add up. I'm not being hypocritical. I'm just making the point the April anomaly doesn't tally with the raw AMSU temperatures. Walterdnes who has often been quite close with his estimates had predicted an anomaly of +0.25 which is quite a big difference. I'm not the only one who thinks it a bit odd see the comment by Sven (07:04:18) on WUWT here wattsupwiththat.com/2009/05/04/natgeo-sun-oddly-quiet-hints-at-next-little-ice-age/Obviously, there is a part of data analysis process which some of us don't understand. Interesting that glc gets upset when giss is accused of fudging the books toward hot but appears quite comfortable alleging bad math on the part of UAH when it comes to cold. I don't think anyone is "fudging the books" and I did not accuse UAH of bad maths (english) , but I can normally see a possible reason for discrepancies in data. At the moment I'm a bit flummoxed because the raw data suggests an anomaly of somewhere between +0.15 and +0.25. But I don't know exactly what channel data is used or what weightings (if any) are used, so there could easily be a factor that I (and others) have not considered. You cannot use a direct comparison between the daily data and monthly data - it has never worked that simply, which is why people have continually struggled to predict monthly anomalies.
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Post by socold on May 5, 2009 22:38:30 GMT
This is the recent annual cycle between UAH and RSS. Started in about 2002 which isconsistent with what Roy Spencer says as that is when AQUA was launched. It could be argued that it started in 2001, but it looks clearer after mid 2002.
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Post by tacoman25 on May 5, 2009 22:44:27 GMT
The good thing is that despite their monthly differences, RSS and UAH have tracked fairly closely in their yearly numbers. They are at least showing the same basic trend in recent years.
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Post by glc on May 5, 2009 23:56:16 GMT
You cannot use a direct comparison between the daily data and monthly data - it has never worked that simply, which is why people have continually struggled to predict monthly anomalies Can't you - why? As it happens I think I may discovered the reason for the discrepancy. On his blog, Roy Spencer writes "the data come from the AMSU instrument flying on the NOAA-15 satellite" He also says "Use the drop-down menu to pick ch5 (AMSU channel 5) which is the channel John Christy and I use to monitor mid-tropospheric temperatures." However, a bit further on, we have "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" Mystery solved! I'm guessing that most of the time the NOAA-15 data is pretty much consistent with the Aqua data. This may be one of those times it isn't. Walterdnes: This suggests the AMSU temperatures might be a better predictor for RSS than for UAH.
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Post by magellan on May 6, 2009 0:18:59 GMT
UAH and RSS use different calibration methods.
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Post by tacoman25 on May 6, 2009 1:24:41 GMT
You cannot use a direct comparison between the daily data and monthly data - it has never worked that simply, which is why people have continually struggled to predict monthly anomalies Can't you - why? As it happens I think I may discovered the reason for the discrepancy. On his blog, Roy Spencer writes "the data come from the AMSU instrument flying on the NOAA-15 satellite" He also says "Use the drop-down menu to pick ch5 (AMSU channel 5) which is the channel John Christy and I use to monitor mid-tropospheric temperatures." However, a bit further on, we have "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" Mystery solved! I'm guessing that most of the time the NOAA-15 data is pretty much consistent with the Aqua data. This may be one of those times it isn't. Walterdnes: This suggests the AMSU temperatures might be a better predictor for RSS than for UAH. That is a plausible explanation, glc...except that comparing AMSU daily temps to RSS, they don't seem to match February or March very well. And according to the AMSU data, it does look like April was cooler than March...which matches the UAH monthly data better. So I wish the mystery was solved, but I'm not sure it is.
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Post by icefisher on May 6, 2009 2:30:23 GMT
Mystery solved! I'm guessing that most of the time the NOAA-15 data is pretty much consistent with the Aqua data. This may be one of those times it isn't. Especially when he points out UAH is picking up an extra 28 degrees of the globe and that Spencer is noting the differences exist primarily in that region (near the poles).
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