date: Thu May 6 16:43:10 2004
from: Phil Jones
subject: [Fwd: Nature Fu et al New Try against UAH MSU Satellite data]
to: Ben Santer
Ben,
You've probably seen all this - the pdf may be useful. This paper may be why Nature
didn't send your paper out for review - well maybe. Saw Heike Langenburg in Nice at the
EGU, but purposely didn't talk to her.
Christy and Spencer's recollection of history is from a distorted view. They barely
mentioned the stratospheric contamination when the first paper came out in 1990. They
must spend all their time defending their series with RSS, Vinnikov/Grody and now this
new one saying their wrong ! Steve Warren and Diane Siedel know what their doing.
Hope all is well with you ! I've agreed earlier in the week to be the CLA (with Kevin)
on
the Atmos. Obs. chapter for 4AR. Kevin and I will have to review all these papers ! The
surface
temp record, precip, extremes and even the odd downward evaporation trends should all
be easy.
Cheers
Phil
Date: Thu, 06 May 2004 08:31:17 -0600
From: Kevin Trenberth
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To: Warren Washington , Jim Hurrell ,
Tom Wigley , Aiguo Dai ,
"Solomon, Susan" , "Jones, Phil."
Subject: [Fwd: Nature Fu et al New Try against UAH MSU Satellite data]
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X-UEA-MailScanner: Found to be clean
See attached paper and commentary below. Christy and Spencer are wrong and fail to
realize that the coherence of the temperatures in stratosphere mean a negative weighting
in one region compernsates for a positive one elsewhere.
Kevin
-------- Original Message --------
Subject: Nature Fu et al New Try against UAH MSU Satellite data
Date: Thu, 6 May 2004 14:05:56 +0300
From: Timo Hämeranta [1]
To:
CC:
Dear all,
Michael E. Schlesinger kindly sent to us the attached Nature article on the study
Fu, Qiang, Celeste M. Johanson, Stephen G. Warren and Dian J. Seidel, 2004. Contribution
of stratospheric cooling to satellite-inferred tropospheric temperature trends. Nature
Vol. 429, No 6987, pp. 55-58, May 6, 2004
From 1979 to 2001, temperatures observed globally by the mid-tropospheric channel of the
satellite-borne Microwave Sounding Unit (MSU channel 2), as well as the inferred
temperatures in the lower troposphere, show only small warming trends of less than 0.1 K
per decade (refs 13). Surface temperatures based on in situ observations however,
exhibit a larger warming of 1e1dba8.gif 0.17 K per decade (refs 4, 5), and global
climate models forced by combined anthropogenic and natural factors project an increase
in tropospheric temperatures that is somewhat larger than the surface temperature
increase. Here we show that trends in MSU channel 2 temperatures are weak because the
instrument partly records stratospheric temperatures whose large cooling trend offsets
the contributions of tropospheric warming. We quantify the stratospheric contribution to
MSU channel 2 temperatures using MSU channel 4, which records only stratospheric
temperatures. The resulting trend of reconstructed tropospheric temperatures from
satellite data is physically consistent with the observed surface temperature trend. For
the tropics, the tropospheric warming is 1e1dbb2.gif 1.6 times the surface warming, as
expected for a moist adiabatic lapse rate.
NATURE Highlights
Global warming: Model answers
A paradox that has cast doubt on the validity of climate models, and on the wisdom of
taking policy decisions based on their predictions, has finally been resolved. There is
now near-universal agreement, even among climate-change 'skeptics', that temperatures
have been rising at the Earth's surface. This warming can be explained largely by the
increase of greenhouse gases, principally carbon dioxide, in the atmosphere. But
according to climate models, if the surface is warming, the lower atmosphere
(troposphere) must be warming too, and 20 years of satellite measurements show no
evidence of tropospheric warming. An explanation for this discrepancy is now at hand. A
significant fraction of the microwave signals received by the satellites' detectors
comes from the stratosphere, which has been cooling in recent decades as a result of the
insulating effect of greenhouse gases. Remove the stratospheric contribution from the
equation and the troposphere is found to be warming at a rate consistent with the
surface warming.
&&&&&
See also Public release date: 5-May-2004
Contact: Vince Stricherz
[2]vinces@u.washington.edu
206-543-2580
[3]University of Washington
New interpretation of satellite measurements confirms global warming
For years the debate about climate change has had a contentious sticking point satellite
measurements of temperatures in the troposphere, the layer of atmosphere where most
weather occurs, were inconsistent with fast-warming surface temperatures.
But a team led by a University of Washington atmospheric scientist has used satellite
data in a new and more accurate way to show that, for more than two decades, the
troposphere has actually been warming faster than the surface. The new approach relies
on information that better separates readings of the troposphere from those of another
atmospheric layer above, which have disguised the true troposphere temperature trend.
"This tells us very clearly what the lower atmosphere temperature trend is, and the
trend is very similar to what is happening at the surface," said Qiang Fu, a UW
associate professor of atmospheric sciences.
He is lead author of a paper documenting the work published in the May 6 edition of the
journal Nature. Co-authors are Celeste Johanson, a UW research assistant and graduate
student in atmospheric sciences; Stephen Warren, a UW professor of atmospheric sciences
and Earth and space sciences; and Dian Seidel, a research meteorologist with the
National Oceanic and Atmospheric Administration's Air Resources Laboratory in Silver
Spring, Md.
The team examined measurements from devices called microwave-sounding units on NOAA
satellites from January 1979 through December 2001. The satellites all used similar
equipment and techniques to measure microwave radiation emitted by oxygen in the
atmosphere and determine its temperature.
Different channels of the microwave-sounding units measured radiation emitted at
different frequencies, thus providing data for different layers of the atmosphere. In
the case of the troposphere which extends from the surface to an altitude of about 7.5
miles it was believed there was less warming than what had been recorded at the surface.
The troposphere temperature was measured by channel 2 on the microwave sounding units,
but those readings were imprecise because about one-fifth of the signal actually came
from a higher atmospheric layer called the stratosphere.
"Because of ozone depletion and the increase of greenhouse gases, the stratosphere is
cooling about five times faster than the troposphere is warming, so the channel 2
measurement by itself provided us with little information on the temperature trend in
the lower atmosphere," Fu said.
Stratosphere temperatures are measured by channel 4 on the microwave units. Fu's team
used data from weather balloons at various altitudes to develop a method in which the
two satellite channels could be employed to deduce the average temperature in the
troposphere. The scientists correlated the troposphere temperature data from balloons
with the simulated radiation in the two satellite channels to determine which part of
the channel 2 measurement had come from the cooling stratosphere and should be removed.
What remained indicated that the troposphere has been warming at about two-tenths of a
degree Celsius per decade, or nearly one-third of a degree Fahrenheit per decade. That
closely resembles measurements of warming at the surface, something climate models have
suggested would result if the warmer surface temperatures are the result of greenhouse
gases. The previous lack of demonstrable warming in the troposphere has prompted some to
argue that climate models are missing unrecognized but important physical processes, or
even that human-caused climate change is not happening.
One reason previous data have not shown enough warming in the troposphere, Fu said, is
because the stratosphere influence on the channel 2 temperature trend has never been
properly quantified, even though there have been attempts to account for its influence.
Those attempts had large uncertainties, so many researchers had simply used the
unadjusted channel 2 temperature trends to represent the temperature trends in the
middle of the troposphere.
Fu's work is supported by the U.S. Department of Energy, the National Science Foundation
and the National Aeronautics and Space Administration.
The findings, he said, could offer a new context for climate change discussion.
"I think everyone can understand our approach," he said. "I think this could convince
not just scientists but the public as well."
###
For more information, contact Fu at 206-685-2070 or [4]qfu@atmos.washington.edu
&&&&..
See The Seattle Times, 6 May 2004 from
[5]http://seattletimes.nwsource.com/html/localnews/2001921103_globalwarm06m.html
By Sandi Doughton
Seattle Times staff reporter
Seattle scientists say the lower atmosphere is heating up, a discovery that, if true,
would overturn one of the main arguments against global warming.
But even before the results were published in today's issue of the journal Nature,
critics launched into a scholarly version of trash-talking, claiming the University of
Washington group is flat wrong.
"It's going to be a very healthy scientific debate," predicted Mike Wallace, a UW
climate-change expert who was not involved in the research. "It will take a while to sit
down and look at these arguments dispassionately."
Qiang Fu, the lead scientist on the new analysis, said he expected controversy because
the topic is central to the debate over climate change and the role of development and
air pollution.
"This is a very important question," he said.
Ample evidence shows that temperatures at the planet's surface have risen more than one
degree Fahrenheit over the past century, causing glaciers to melt and sea ice to thin.
But until now, studies of the Earth's lower atmosphere - the part where weather occurs -
have shown little or no temperature increase.
Global-warming skeptics say that suggests human activity is not changing the climate
significantly.
Fu and his colleagues re-examined temperature data collected from weather satellites
between 1979 and 2001.
The satellites measure temperature in both the lower and upper atmosphere.
While a human-caused global warming would be expected to raise the temperature in the
lower atmosphere, computer models have shown it would have the opposite effect in the
upper layer called the stratosphere. And indeed, temperatures there have been dropping
steeply over the past several decades.
Because satellite measurements from the different layers overlap, Fu suspected the
cooling in the stratosphere might be masking any temperature increase in the lower
atmosphere.
Fu's team developed a statistical approach to subtract the stratosphere's influence and
found the hunch was correct: Temperatures in the lower atmosphere rose about one-third
degree per decade, slightly more than the increase seen at the planet's surface during
the same time frame.
"I believe this shows the satellite temperatures can no longer be used as evidence to
claim that global warming is not happening in the atmosphere," Fu said. "I think this
could convince not just scientists but the public as well."
Some fellow scientists were not only unconvinced but dismissive of the study.
John Christy, director of the Earth System Science Center at the University of Alabama
at Huntsville, has been analyzing the same satellite data since the early 1990s, finding
no evidence of a significant temperature increase. He issued a rebuttal yesterday,
saying the UW group went too far in subtracting the stratospheric cooling.
"The method they used creates a false warming signal," said Christy, who believes that
humans are changing the climate, but that the changes are modest and not likely to cause
ecological disaster.
"Most of the predictions are too alarmist," he said.
Fu deflected the criticism and predicted his team's new study will be the final answer
to the long-standing puzzle about atmospheric warming.
"I'm confident this will not be an issue anymore," he said.
As an independent observer, Wallace said he thinks that Fu's approach seems reasonable,
but that the debate won't be settled until all the scientists involved have time to hash
out the data and the methods.
"I won't profess to claim the verdict is in yet," he said.
Sandi Doughton: 206-464-2491 or [6]sdoughton@seattletimes.com
Copyright © 2004 The Seattle Times Company
&&&&&&&..
The UAH response is as follows:
University of Alabama in Huntsville, 5 May 2004
For Additional Information:
Dr. Roy Spencer, (256) 961-7960
Dr. John Christy, (256) 961-7763
Phillip Gentry, (256) 824-6420
EMBARGOED: For release after 2 p.m., Wednesday, May 5, 2004
New climate study finds 'global warming' by subtracting cooling that wasn't there
HUNTSVILLE, AL (May 5, 2004) -- A new study of global temperature data reports this week
the discovery that significant global warming can be found by subtracting from the
temperature record more cooling than was actually there.
"You can't subtract more signal than is there, but that's what they've done," said Dr.
Roy Spencer, a principal research scientist in the Earth System Science Center at The
University of Alabama in Huntsville (UAH). "They've subtracted more than is actually
there."
The study in question, by Fu et al., is published this week in Nature. The authors claim
to find significant atmospheric warming over the past 25 years when cooling that has
taken place in the stratosphere during that time is removed from the tropospheric
temperature data gathered by instruments aboard NOAA satellites.
The problem, says Spencer, is that the study uses a negative weighting" function that
removes more stratospheric cooling than actually appears in the data, thus creating a
spurious warming signal.
"Simply put, this method over corrects for stratospheric cooling," said Dr. John
Christy, a professor of atmospheric science at UAH and director of the ESSC. "We tried
this same technique in the early 1990s but it didn't work. Instead, Roy developed a
method for accurately removing stratospheric temperatures from the data and we published
that in 1992."
Spencer and Christy were the first to use data from microwave sounding units aboard NOAA
satellites to track global temperature trends. Over the past 13 years they have made
several corrections to their dataset as different problems have been identified.
The satellite sensors, which have been in service since late November 1978, show a
long-term lower atmosphere global warming trend of about 0.08 C (0.14 degrees
Fahrenheit) per decade in the past 25 years. This trend has been corroborated by U.S.,
British and Russian studies comparing the satellite data to temperature data gathered by
weather balloons.
&&&&&&..
Roy W. Spencers response in TCS is as follows:
When Is Global Warming Really a Cooling?
By Roy Spencer
Published
05/05/2004
[7]1e1dbc6.gif [8]E-Mail
[9]1e1dbd0.gif [10]Bookmark
[11]1e1dbda.gif [12]Print
[13]1e1dbe4.gif [14]Save
TCS
Much media attention is focusing on the forthcoming big-budget climate disaster movie
"The Day After Tomorrow" and how much scrutiny the "science" on which it is based
deserves. But there are some developments in the world of serious climate science that
certainly deserve greater scrutiny.
A new paper^1 appearing today in the journal Nature purports to solve the long standing
"problem" of the satellite-based global temperature record not showing much warming over
the last 25 years (only +0.085 deg C/decade -- about a third of what is expected from
climate models for the troposphere). Instead, all it does is help answer the question:
"is the quality of peer review in the popular science journals getting worse?" (The
answer is "yes.")
By way of background, the Microwave Sounding Units (MSU) on the NOAA polar orbiting
satellites measure deep layers of the atmosphere, with each instrument channel measuring
the average temperature of a different layer (see Fig. 1). [15]John Christy, a professor
of atmospheric science at the University of Alabama, Huntsville, and I discovered in
1990 that these instruments were so stable in their calibration that we have been using
them ever since for climate monitoring of tropospheric and lower stratospheric
temperatures since the satellite record began in 1978.
The lowest layer (the troposphere) is measured by channel 2, and this is where global
warming is supposed to occur. The lower stratospheric layer is measured by MSU channel
4. Christy and I have measured substantial cooling (-0.47 deg. C/decade) in this layer
over the same 25 year period.
But because the layers measured by the satellite are so thick, there is a intermingling
of the warming and cooling signals. This means that warming in the tropospheric channel
would be partly cancelled by stratospheric cooling occurring in the upper portion of
this layer. Because of this problem, we devised a lower tropospheric retrieval^2 based
upon different Earth viewing angles from the MSU tropospheric channel. As can be seen in
the accompanying figure, this removes the stratospheric influence and so allows us to
monitor the lower and middle troposphere for signs of global warming.
1e1dbee.gif
Fig. 1 Microwave Sounding Unit weighting functions for channels 2 and 4, along with
derived weighting functions meant to remove the influence of lower stratospheric cooling
on MSU channel 2 by Spencer & Christy (1992, "TLT") and Fu et al. (2004). The Fu et al.
weighting function shows substantial negative weight above 100 hPa, a pressure altitude
above which strong cooling has been observed by weather balloon data. This leads to a
misinterpretation of stratospheric cooling as tropospheric warming.
Enter the new Nature study. The authors, noticing that channel 4 measures the extreme
upper portion of the layer that channel 2 measures (see Fig. 1), decided to use the MSU
channel 4 to remove the stratospheric influence on MSU channel 2. At first, this sounds
like a reasonable approach. We also tried this thirteen years ago. But we quickly
realized that in order for two channels to be combined in a physically meaningful way,
they must have a large percentage of overlap. As can be seen in Fig. 1, there is very
little overlap between these two channels. When a weighted difference is computed
between the two channels in an attempt to measure just the tropospheric temperature, an
unavoidable problem surfaces: a large amount of negative weight appears in the
stratosphere. What this means physically is that any attempt to correct the tropospheric
channel in this fashion leads to a misinterpretation of stratospheric cooling as
tropospheric warming. It would be possible for their method to work (through
serendipity) if the temperature trends from the upper troposphere to the lower
stratosphere were constant with height, but they are not. In this instance, the negative
(shaded) area for the Fu et al. weighting function in Fig. 1 would be cancelled out by
its positive area above about 200 millibars. Unfortunately, weather balloon evidence
suggests the trends change from warming to strong cooling over this altitude range.
This kind of mistake would not get published with adequate peer review of manuscripts
submitted for publication. But in recent years, a curious thing has happened. The
popular science magazines, Science and Nature, have seemingly stopped sending John
Christy and me papers whose conclusions differ from our satellite data analysis. This is
in spite of the fact that we are (arguably) the most qualified people in the field to
review them. This is the second time in nine months that these journals have let papers
be published in the satellite temperature monitoring field that had easily identifiable
errors in their methodology.
I will admit to being uneasy about airing scientific dirty laundry in an op-ed. But as
long as these popular science journals insist on putting news value ahead of science,
then I have little choice. The damage has already been done. A paper claiming to falsify
our satellite temperature record has been published in the "peer reviewed" literature,
and the resulting news reports will never be taken back. This is one reason increasing
numbers of scientists regard Science and Nature as "gray" scientific literature.
1. Fu, Q., C.M. Johanson, S.G. Warren, and D.J. Seidel, 2004: Contribution of
stratospheric cooling to satellite-inferred tropospheric temperature trends. Nature,
429, 55-58.
2. Spencer, R.W., and J.R. Christy, 1992: Precision and radiosonde validation of
satellite gridpoint temperature anomalies, Part II: A tropospheric retrieval and trends
during 1979-90. J. Climate, 5, 858-866.
From [16]http://www.techcentralstation.com/050504H.html
&&&&&..
The World Climate Report, 5 May 2004, from
<[17]http://www.greeningearthsociety.org/wca/2004/wca_17a.html> is as follows:
Assault >From Above
Its common knowledge that for twenty-five years the satellite-based temperature record of
the lower atmosphere shows much less warming than surface observations or climate model
predictions. The big question is, Why?A new study in Nature by University of Washingtons
Qiang Fu and colleagues claims the satellite measurements are in error because they include
a cooling effect from the atmospheric layer just above it. But in formulating their case,
the authors assume the impossible.
The idea behind what Fu et al. report to Nature is simple enough. Satellite-based
temperature measurements of the earths atmosphere are not collected from a single altitude.
They represent the weighted average temperature of a rather large atmospheric layer, one so
large that the measurements supposedly representing the middle to upper troposphere (from
about five to eight miles in altitude) actually include part of the lower stratosphere
(from about eight to twelve miles up), as Figure 1 shows. The extra few miles potentially
are problematic because ozone loss in the stratosphere leads to a cooling trend in that
layer.
By way of background, ozone absorbs incoming solar radiation. The radiation warms the
air, meaning the less ozone there is, the less warming there can be. The stratospheres
cooling trend to some degree contaminates the temperature trend observed in the mid- to
upper troposphere and perhaps masks the warming from an enhanced greenhouse effect. So what
happens if the stratospheric cooling component is removed from the tropospheres temperature
record? Thats what Fu and colleaguesset out to do.
1e1dc20.jpg
Figure 1. Atmospheric contribution to the satellite-based temperature observations of
the stratosphere (dashed red line) and mid- to upper- troposphere (solid blue line).
Notice the region of overlap (shaded pink) that indicates some portion of the
stratosphere contributes to observations of the tropospheres temperatures.
They set out to use satellite temperature measurements of the stratosphere as an
indicator of how much cooling has worked its way into the history of tropospheric
temperatures. By combining the two datasets in such a way as to remove stratospheric
cooling contamination, Fu concludes true temperatures in the troposphere have been
warming at a greater rate than that reported to date, one which brings the satellite
measurements more in line with surface observations and climate model projections. In
this way, they believe they have solved the riddle concerning the large discrepancy
between the trends in surface temperatures and those of the troposphere a discrepancy
climate models are not able replicate.
As in Paul Simons immortal lyric, Slow down, you move too fast.
Long ago, the co-founders of the original satellite-based temperature history
(University of Alabama-Huntsville scientists John Christy and Roy Spencer) recognized
that stratospheric temperatures were contaminating satellite measurements of the middle
and upper troposphere. Spurred by a desire to produce a truetropospheric-only
temperature dataset, in the late 1980s and early 1990s Spencer and Christy extensively
examined various methodologies, including one like Fu et al. describe. They quickly
realized that such a technique is infeasible because it produces a situation that
violates a basic law of physics namely, energy must be positive (Figure 2).
1e1dc3e.jpg
Figure 2. The stratospheric contribution to the satellite-based measurements of
tropospheric temperatures. Solutions that dont violate the basic laws of physics must
have a weighting that is greater than or equal to zero.
The stratospheric contribution to raw tropospheric temperature observations is
represented by the red line (top). The best, most physically realistic adjustment to the
raw observations uses data in the stratosphere to adjust tropospheric temperatures and
is represented by the green line (middle).
The solution used by Fu et al. appears as the blue line (bottom). The physically
impossible negative contribution (shaded region with hatching) roughly equals the amount
of positive contribution (shaded region without hatching), such that the total
contribution from the stratosphere equals zero.
There are three curves in Figure 2. The top, red line represents the stratospheres
contribution to temperature measurements of the troposphere. Ideally, this value would
be zero, indicating no contribution. By combining the tropospheric measurements with
actual measurements of stratospheric temperature, it is possible to subtract outsome of
the stratospheres impact. But this must be carefully done or else a non-physical result
is produced. You cant remove more than you have at the outset.
The zero(black, horizontal) line represents the limit of removal. A result below
this line relies on negativeenergy, which defies a law of physics. The middle (green,
dashed) line shows the best, physically possible solution that can be produced using
data from the stratosphere to adjust temperatures in the troposphere. It still makes a
sizeable stratospheric contribution.
The blue (bottom) line represents Fu et al.s solution. They succeed in setting the
stratospheric contribution roughly equal to zero (the average of the area above and
below zero), but in doing so they create an unrealistic representation of the real
atmosphere. Though the portions in the stratosphere appear to cancel each other, the
problem is this: The atmosphere in the negative portion is cooling rapidly (because of
ozone depletion) while the atmosphere in the positive portion is changing very little.
In terms of net effect, Fu et al. multiply the rapid-cooling-trend layer by a
too-large negative factor (making it appear to warm), while multiplying a
near-zero-trend layer by a positive factor (which will have a very minor impact). Rather
than canceling the stratospheric influence, Fus method adds a spurious warming trend to
the net result. Simply put, Fu et al. overcorrect for stratospheric cooling.
In the interest of good science, Spencer and Christy abandoned this technique years
ago because even the best acceptable solution (the middle curve in Figure 2) still has
too much stratospheric influence. Instead, they developed a clever solution that makes
use of different viewing angles by a single channel aboard the satellite. In this way,
they measure temperatures occurring lower in the atmosphere and are able to produce the
now famous lower tropospheric temperature history, one that essentially is free of
stratospheric effects, and one that shows only about half as much global warming during
the past twenty-five years as does the network of surface thermometers scattered across
the globe.
Just a few weeks ago, another in a long string of publications demonstrated anew
why we can have confidence in Spencer and Christys dataset (see
[18]http://www.co2andclimate.org/wca/2004/wca_15f.html for details). But here we are,
more than a dozen years down the road and a technique discarded as physically
implausible rears its head again. How Fu et al.s physically-impossible result made it
through Natures peer review process is unfathomable. Yet again, the reviewers Nature
relies on to ensure scientifically sound results fail the needs of the publication.
Are Natures editors intentionally allowing articles on certain topics to be
published despite a lack of scientific worthiness? Are the editors underqualified to
judge the scientific merit of the research or are they unable to assign competent
reviewers to do so? Whichever the case may be, the result is the same: When it comes to
climate change, Natures reputation is becoming severely degraded.
References:
Christy, J. R., and W. B. Norris, 2004: What may we conclude about global tropospheric
temperature trends? Geophysical Research Letters, 31, L06211, doi:10.1029/2003GL019361.
Fu, Q., et al., 2004. Contribution of stratospheric cooling to satellite-inferred
tropospheric temperature trends. Nature, 429, 55-58.
Spencer, R.W., and J.R. Christy, 1990. Precise monitoring of global temperature trends
from satellites. Science, 247, 1558-1562.
&&&&&&&&..
See also World Climate Report April 2004 from
<[19]http://www.greeningearthsociety.org/wca/2004/wca_15f.html>
Nothings Changed
Major systematic problems in general circulation models (GCMs) are apparent in the
discrepancy between observed temperature trends in the lower atmosphere and the trend
predicted by the models. As long as these problems persist, GCMs cannot provide reliable
estimates of future climate conditions.
The longstanding benchmark time series of temperatures in the middle to lower
atmosphere is that developed by University of Alabama-Huntsville (UAH) scientists John
Christy and Roy Spencer. It employs measurements made by microwave sounding units (MSUs)
carried aloft on NASA satellites. As the satellites orbit the earth, the MSUs observe
microwave emissions from oxygen molecules in the earths atmosphere. The emissions vary
depending on the temperature of the emitting molecule. Thus, they provide an accurate
indication of atmospheric temperature and are real-world observations.
The UAH record indicates that the temperature of the middle atmosphere (at an altitude
of about 15,000 feet) has warmed only at a rate of +0.03°C (±0.05°C) per decade in the 25
years since inception of high-quality, global satellite temperature measurements. The
absence of much warming in the UAH record contrasts with temperature measurements from the
earths surface which have warmed at about 0.17ºC warming per decade during the same period.
The UAH record also contrasts with GCM projections of how the middle atmosphere should
behave. Climate models project the middle to lower atmosphere generally will warm a bit
faster than the surface under conditions of an enhancing greenhouse effect.
Because of these contrasting discrepancies, the UAH temperature record has been
subjected to intense scrutiny. Advocates of the need to do somethingabout global warming
seemingly prefer climate model output to actual observations because GCMs, one and all,
project a much more scary future climate than observations suggest is likely.
Several researchers developed alternative satellite temperature histories because they
believed the methods employed by the UAH researchers in processing the microwave data are
inadequate or in error. Carl Mears, Frank Wentz and Matthias Schabel of Remote Sensing
Systems (RSS) developed one such alternative history. Konstantin Vinnikov and Norman Grody
(VG) are authors of another. The RSS temperature record shows four times the warming of
that in the UAH record at +0.12 °C (±0.02°C) per decade. The rate of warming in the VG
record is greater still: +0.24°C (±0.02°C). We compare these histories in Figure 1.
1e1dc70.gif
Figure 1. Annual MSU temperature anomalies (departures from the long-term mean) as
calculated by UAH, RSS, and VG. (adapted from Christy and Norris, 2004).
Trends in the RSS and VG records bring middle atmospheric warming more in line with
surface measurement and, consequently, closer to climate model forecasts of what should
be happening in the lower to middle atmosphere. The question is: Which of the three MSU
records most accurately reflects true atmospheric temperature? They cant all be right
because each purports to measure precisely the same quantity (temperature in the mid- to
lower atmosphere) and yet result in significantly different records.
Each research group begins with identical raw data collected by the same NASA
satellites. The problem is that the average lifetime of the instruments aboard the
individual satellites is only about 3-4 years. This has resulted in eleven different
satellites making measurements over the past 25 years. What is in contention is how each
individual satellites record is combined with others to create one continuous time
series.
Satellitesorbits degrade. So do the instruments onboard. These changes lead to
measurement errors. Before each research group can compile an accurate history
sufficiently robust for trend calculations, they must compensate for such errors. Each
research group has its own correction scheme and each staunchly defends its methods. Yet
they are so different as to result in the discrepancies shown in [20]Figure 1.
However there does exist a possible external referee to help resolve these
differences. That referee is the independent measurement of temperature in the lower
atmosphere made by thermometers carried aloft twice daily by weather balloons released
from locations around the world.
It would seem any research team eager to demonstrate that its MSU temperature
realization is the best would carefully compare its history with that of the weather
balloons. However only one group does so the UAH scientists. Theyve published their most
recent result in Geophysical Research Letters (see our Related Readingbelow for
descriptions of earlier UAH results).
John Christy and William Norris selected high-quality weather balloon observations
(from records kept at the U. S. National Climatic Data Center) from locations around the
world between January 1979 through July 2001 and compared them with the UAH satellite
data. They perform a series of comparisons designed to account for disparities in the
weather-balloon data that can arise from missing data or changing instruments. In all
cases, they find very close correspondence between the UAH satellite record and the
independent weather balloon record. In fact, the differences between the records are
statistically indistinguishable.
Data appropriate and necessary for Christy and Norris to extend their detailed
comparison to the other two MSU satellite records is not available. However, they
generally conclude that because the three MSU records differ from one other, and because
the independent weather balloon data closely match one of the three, then the other two
(by definition) must not enjoy close correspondence. This finding implies that the RSS
and VG records are in error.
This is not the only research published by UAH scientists comparing their satellite
record with the record of weather balloons; it is only the latest in a series of such
comparisons. Others used weather balloon data from a variety of sources including the U.
K.s Hadley Centre, the U. S. National Center for Environmental Prediction, the U. S.
National Climatic Data Center, and the Russian Research Institute for Hydrometeological
Information (see
[21]http://www.co2andclimate.org/climate/previous_issues/vol8/v8n18/feature.htm for the
results from these other comparisons). No matter from where the data comes, the results
are the same an extremely close match between the weather balloons and the UAH satellite
temperature record.
The evidence presented by the UAH researchers seems as conclusive as any that
exists. It demonstrates that the most accurate MSU record is that with the least amount
of warming during the past 25 years and the one that differs most from predictions
generated by climate models, when independent weather balloon temperature data serves as
referee. It seems to us that these basic facts can stand until and unless the other MSU
research groups provide appropriate data and analyses to demonstrate otherwise.
References
Christy, J. R., and W. B. Norris, 2004: What may we conclude about global tropospheric
temperature trends?, Geophysical Research Letters, 31, L06211, doi:10.1029/2003GL019361.
Christy J. R. et al., 2003: Error estimates of version 5.0 of MSU-AMSU bulk atmospheric
temperatures, Journal of Atmospheric and Oceanic Technology, 20, 613-629.
Mears, C. A., M. C. Schabel, and F. J. Wentz, 2003: A reanalysis of the MSU channel 2
tropospheric temperature record, Journal of Climate, 16, 36503664.
Vinnikov, K. Y., and N. C. Grody, 2003: Global warming trend of mean tropospheric
temperature observed by satellites, Science, 302, 269272.
Related Reading:
[22]http://www.co2andclimate.org/wca/2003/wca_13a.html
[23]http://www.co2andclimate.org/wca/2003/wca_6c.html
[24]http://www.co2andclimate.org/Articles/2003/vca9.htm
[25]http://www.co2andclimate.org/climate/previous_issues/vol8/v8n18/feature.htm
[26]http://www.co2andclimate.org/climate/previous_issues/vol5/v5n10/feature1.htm
[27]http://www.co2andclimate.org/climate/previous_issues/vol3/v3n13/feature1.htm
[28]http://www.co2andclimate.org/climate/previous_issues/vol3/v3n21/feature.htm
[29]http://www.co2andclimate.org/climate/previous_issues/vol3/v3n24/feature1.htm
&&&&&&
Well, "The method they used creates a false warming signal," said Christy, and Wallace
said he thinks that Fu's approach seems reasonable, but that the debate won't be settled
until all the scientists involved have time to hash out the data and the methods.
Comments appreciated from all of you, dear recipients.
All the best
Timo Hämeranta
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Timo Hämeranta, LL.M.
Moderator, Climatesceptics
Martinlaaksontie 42 B 9
01620 Vantaa
Finland, Member State of the European Union
Moderator: [30]timohame@yahoo.co.uk
Private: [31]timo.hameranta@pp.inet.fi
Home page: [32]http://personal.inet.fi/koti/hameranta/climate.htm
Moderator of the discussion group "Sceptical Climate Science"
[33]http://groups.yahoo.com/group/climatesceptics
"To dwell only on horror scenarios of the future
shows only a lack of imagination". (Kari Enqvist)
"If the facts change, I'll change my opinion.
What do you do, Sir" (John Maynard Keynes)
"As long as we are unable to explain the evident
inconsistencies that fly in the face of climate
alarmism, attempts to associate scientific scepticism
with Holocaust denial can only be regarded as
political incitement."
(Benny J. Peiser, CCNet January 30, 2003)
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
--
****************
Kevin E. Trenberth e-mail: [34]trenbert@ucar.edu
Climate Analysis Section, NCAR [35]www.cgd.ucar.edu/cas/
P. O. Box 3000, (303) 497 1318
Boulder, CO 80307 (303) 497 1333 (fax)
Street address: 1850 Table Mesa Drive, Boulder, CO 80303
Prof. Phil Jones
Climatic Research Unit Telephone +44 (0) 1603 592090
School of Environmental Sciences Fax +44 (0) 1603 507784
University of East Anglia
Norwich Email p.jones@uea.ac.uk
NR4 7TJ
UK
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