Comments on: Putting myths about UAH and RSS satellite data to rest

By: Gerald Browning

Gerald Browning — Wed, 18 Feb 2009 22:22:16 +0000

Andrew,

I just read the info on wikipeidia and it states very clearly that the conversion from satellite radiances to temperature is not a simple process and in fact different results are obtained by different methods. I think Dr. Christy needs to be asked about this in a bit more detail.

Jerry

By: Gerlad Browning

Gerlad Browning — Wed, 18 Feb 2009 22:15:06 +0000

Andrew,

The process of obtaining the temperature from the satellite radiance data is an ill posed problem, i.e. one is inverting an integral and this inversion is especially difficult in the presence of clouds. It is my understanding (based on experience) that the temperture retrieval is an iteration process that uses surface temperature readings in the iteration process. Please ask Dr. Christy again if this is the case or not. If he claims it is not the case, I will dig out the mathematics to prove the point.

Jerry

By: tomcat

tomcat — Tue, 02 Sep 2008 20:50:42 +0000

I thought that the RSS used a climate model for the diurnal correction, so the question is what are the various inputs used for the climate model and how are the radiative properties of the climate model and how sensitive are they to atmospheric CO2 quantities?

By: J

Tue, 25 Mar 2008 16:44:59 +0000

Patrick:

Those links are from 1997 and 2000. Over the years since then, several errors were discovered in the methods used by Christy et al for processing the satellite data. The MSU temperature trends now match the surface records quite closely (IIRC, RSS’s trend is slightly higher than GISS, while UAH’s is slightly lower).

In the previous thread, I was defending the proposition that the satellite microwave radiometer data were not “tuned” to match the surface temperature trend. I’m glad that Anthony took my advice and posed this question to Dr Christy. Sometimes it seems like the same arguments keep getting recycled over and over again. Here’s hoping that this particular allegation has now been conclusively put to rest.

By: Patrick Hadley

Patrick Hadley — Thu, 20 Mar 2008 12:41:43 +0000

I know this is now a rather old thread, since there have been so many new ones recently, but these dated posts about the satellite trends being different from the surface trends seem relevant:
http://science.nasa.gov/newhome/headlines/essd06oct97_1.htm

http://science.nasa.gov/headlines/y2000/ast21jul_1m.htm

By: sooner_wx

sooner_wx — Fri, 14 Mar 2008 00:44:40 +0000

Anthony,

Here is the info:

Randall, R. M., and B. M. Herman (2008), Using limited time period trends as a means to determine attribution of discrepancies in microwave sounding unit–derived tropospheric temperature time series, J. Geophys. Res., 113, D05105, doi:10.1029/2007JD008864.

http://www.agu.org/pubs/crossref/2008/2007JD008864.shtml

REPLY: Thanks so much!

By: sooner_wx

sooner_wx — Thu, 13 Mar 2008 19:52:08 +0000

JM,

Randall and Herman (2008) conclude the differences between the trends (shown in the LT channel over land) of UAH and RSS is primarily due to diurnal corrections.

REPLY: By chance would you have a link to that paper? Thanks, Anthony

By: JM

JM — Thu, 13 Mar 2008 17:11:28 +0000

sooner_wx,
Would the disagreement in decadal trends be from those differing methods?

By: sooner_wx

sooner_wx — Wed, 12 Mar 2008 11:51:35 +0000

JM,

The RSS and UAH groups use different methods to determine diurnal corrections. UAH uses techniques from the satellite data itself (Different methods for Mid tropospheric channel vs Lower tropospheric channel). RSS uses hourly output from a climate model control run.

By: JM

JM — Tue, 11 Mar 2008 23:05:30 +0000

Are diurnal corrections based on GCM simulations of the diurnal cycle?

By: Andrew

Andrew — Tue, 11 Mar 2008 00:34:43 +0000

J, given that the RSS team has no reason not to believe in AGW and their data mostly agrees with UAH, I’d say that its totally unfounded to be so suspicious.

By: Gary Gulrud

Gary Gulrud — Mon, 10 Mar 2008 21:27:43 +0000

Gentle reader, although any reasonable investigator is ill-disposed, on principle, toward ‘conspiracy theories’, I would like to insert a caveat regarding disinformation.
A successful practice is to feed the unwary good, even much-appreciated information inorder to insert something false that leads one astray.
As an example:

http://en.wikipedia.org/wiki/Stefan-Boltzmann_law

Spot the effluent. Now review the foregoing commentary with an eye for this practice.

By: Peter VW

Peter VW — Mon, 10 Mar 2008 20:49:25 +0000

Here is the ground track for 1 day of NOAA 18 as seen from above the north pole. I used Satellite Toolkit and their database of TLE .

http://www.flickr.com/photos/24537036@N02/2324711796/

I described SSOs over in the previous discussion of …3 of 4 global metrics

By: Bob B

Bob B — Mon, 10 Mar 2008 19:35:53 +0000

New Feb 2008 RSS numbers in also show zero anomaly:

ftp://ftp.ssmi.com/msu/monthly_time_series/rss_monthly_msu_amsu_channel_tlt_anomalies_land_and_ocean_v03_1.txt

By: J

Mon, 10 Mar 2008 13:30:16 +0000

Anthony, it may seem odd that a “polar-orbiting” satellite doesn’t actually cross over the poles, but there are good reasons for it. In point of fact, most earth observation satellites are in “near-polar orbits”, to ensure that the equatorial crossing times are sun-synchronous. In essence, the orbital altitude and inclination are chosen so as to ensure that the satellite’s orbit pattern keeps time with the rotation of the earth, so each ascending or descending node’s ECT is at the exact same (solar) time.

Unfortunately, due to drag, the orbits decay over time, and the ECT drifts slightly from year to year. This is what adds most of the complexity to the MSU data analysis.

Anyway, thanks for posting this. It is nice to see some of the misinformation in the comments in the previous thread get cleared up. Unfortunately, the misinformation and conspiracy theories just keep coming:

To allay this suspicion, that the calculations are cooked to get a politically acceptable result, we really should have access to the raw data, and the algorithm by which it averaged.

Seems to me that if we simply took the average observed temperature at wavelengths with good penetration, that would be a good measure of global warming or cooling, and would not be vulnerable to suspicion of too clever by half corrections and adjustments.

You can get access to the original MSU data. That’s how several different groups (not just UAH and RSS) have come up with their own tropospheric temperature trends. The microwave emissions measured by MSU / AMSU come from a fairly broad region of the troposphere; in order to isolate the signal from the lower troposphere, it’s necessary to somehow remove the signal from higher altitudes. UAH and RSS use quite different methods for doing this, the difference in methods may explain much of the (slight) difference in estimated trends, and it’s not entirely clear which method is better. If you think you have a better way of doing this, by all means go ahead.

Talk about the MSU analysis being “cooked to get a politically acceptable result” is irresponsible, and just feeds paranoia.