Hot/Cold air Alert – it’s the data stupid!

I posted some observations on the report from the UK Meteorological Office Hadley centre which they published on Friday 12/8/05 in Science on their attempts to resolve the apparent paradox, that whilst the IPCC in 2001 suggested from direct observations that the Earth's surface had warmed rapidly since 1979, the air in the lower 8 km of the atmosphere above the surface had not. This difference however, most evident in tropical zones, directly contradicted climate models which simulated larger warming aloft, rather than at the surface they came to the conclusion after running datasets through 18 world climate models :

1. The models don’t work properly …

2. There is a problem with the data …

The good / bad news is that Science also published the views of 2 other sets of researchers which…. Well let’s cover what they say. First up to the plate is study leader Steven Sherwood, an associate professor of geology and geophysics at Yale. He worked with Researchers at the US' National Oceanic and Atmospheric Administration (NOAA)(1)who says ,

"Even though models predict a close link between atmospheric and surface temperatures, there has been a large difference in the actual measurements." Which he says, “This has muddied the interpretation of reported warming.”

The reason is the data collected were incorrect.
1) There was problem with the balloon radiosonde temperature recording units.

For the last 40 years radiosonde temperature information from balloons has been collected twice each day from stations around the world at local times that correspond to 00:00 and 12:00 Greenwich Mean Time (GMT) . Some measurements were taken in daylight, others in darkness. The key to the error in climate change estimates lay in instrument design, according Sherwood et.al. With exposed sensors, measurement taken in daylight read too warm, whilst solar heating had a measurable impact on early designs, the effect became negligible in more recent designs. After taking this problem into account, and by separating out nightime and daytime data separately, rather than averaging them daily , the researchers estimate(sic) there has been an increase of 0.2 degree Celsius (°C) in the average global temperature per decade for the last thirty years (Total 0.6 C or 1 F’ ish).

Over the next century, global surface temperatures they extrapolate excitedly are expected to increase by 2 to 4°C. However, year-to-year and region to region increases may vary considerably ( a prudent note of scientific caution here) , with a smaller increase in the tropics but 10 degrees or more possible (wow!) in some Polar Regions.

“Unfortunately, the warming is in an accelerating trend — the climate has not yet caught up with what we’ve already put into the atmosphere,” said Sherwood in his down home folksy way. “There are steps we should take, but it seems that shaking people out of complacency will take a strong incentive.” Not to mention putting a great deal of emphasis on the “estimated” increase of 0.2 C per decade.

"It's like being outside on a hot day -- it feels hotter when you are standing in the direct sun than when you are standing in the shade," said Sherwood in a brave attempt at unfolding the mysteries of science for the common man , and concludes with a raffish, under scientist, arrogant remark that gets the headlines in downtown Palookaville….. "We can't hang our hats on the old balloon numbers."

The story doesn’t finish here folks, there is nothing like a combative climatologist to sneak in another blow from …well outta the sun.

2) There was a problem with defining the time / sighting of the Microwave Sounding Units (MSUs) and Advanced Microwave Sounding Units (AMSUs) flying on NOAA's polar orbiting weather satellites


On another tack, Carl Mears and Frank Wentz of Remote Sensing Systems (RSS) in Santa Rosa, Calif., have been busy examining satellite data, collected since 1979 by National Oceanic and Atmospheric Administration weather satellites. They have found that the satellites were subject to orbital decay caused, they believe, because the orbital period of a satellite changes slowly over that satellite's lifetime, due to friction with the outer reaches of the atmosphere. If due allowance is not made for such changes, spurious long-term trends can appear in the data, so if the satellite had drifted in orbit,it would throw off the timing of temperature. (remember 00:00 and 12:00 GMT) Essentially, the satellites were increasingly reporting nightime temperatures as daytime ones, heating from tropical sunlight was skewing the temperatures reported by sensors, making nights look as warm as days.

The University of Alabama in Huntsville estimate of the globally averaged trend since 1979 to the present has been +0.09 deg. C/decade, considerably below the surface thermometer estimate that has been hovering around +0.20 deg. C/decade for the same period of record…... and the 0.2 deg.C/decade that Sherwood’s revised ballon figures produced.

So RSS say, the satellite recession was leading to the recording of a false cooling trend. The team (see pic) also found an algebraic error in the calculations and have produced a revised final estimate of the global lower tropospheric trend through 2004 as +0.19 deg. C/decade, very close to the surface thermometer estimate, and this constitutes the primary news value of their report.

The happy ending is “Once corrected, the satellite and balloon temperatures align with other surface and upper-atmosphere measures, as well as climate change models”, says climate expert Ben Santer of Lawrence Livermore National Laboratory in California .

If you seek a more detailed review of these three papers you are advised to read “Some Convergence of Global Warming Estimates” by Roy Spencer who undertook the original University of Alabama in Huntsville, "UAH" studies, published on 11th August by the George C Marshall Centre they have undertaken a review of their procedures and calculations in the light of the RSS criticism and have proposed a decadal temperature rise of 0.12 C…Spencer says rather pointedly concerning the publication of the three papers simultaneously…

” I only hope that the appearance of these three papers together, with considerable overlapping of authorship, does not represent an attempt to make measurements fit theoretical models.” He also makes a plea that the shifts in the global warming debate is out of the realm of "is warming happening?" to .... "how much has it warmed, and how much will it warm in the future?". (Equally valid questions to debate are "how much of the warmth is man-made?", "is warming necessarily a bad thing?", and "what can we do about it anyway?"). This he says is where the debate should be….and so say all of us.

In a nutshell what these 3 papers tell us, is - Surface temperature records show temperature increase 0.20 degrees C per decade over the last 3 decades in tropical zones. (Although no-ne seems to have queried the accuracy of such man made datasets...yet ?)

Balloon tropospheric temperature records showed no temperature increase in this period. This has now been revised for two reasons, one there was a disparity in day / night time recording die to solar heating, which was lost due to diurnal averaging, and because radiosonde equipment improved in design to reduce this effect so long term linear comparisons were invalid. As a result it is estimated that the tropospheric temp erature rise was a decadal 0.20 deg. C.

Previous analysis of Satellite records failed to correctly take into account satellite recession and there was a small algebraic error in the original satellite studies as a result of these problems which were corrected it is estimated that the tropospheric temperature rise was a decadal 0. 19 deg. C.

The original team who worked on their satellite data have re-d0ne their calculations in the light of the revised views of satellite recession and algebraic error and say the decadal temperature rise is 0.12 deg C.


(1) (Co-authors on the paper were Cathryn Meyer at Yale and John Lanzante at the NOAA/ Geophysical Fluid Dynamics Laboratory at Princeton. The research was funded by the NOAA Climate and Global Change Program and the National Science Foundation. )
REFERENCES
Mears, C.A., and F.J. Wentz, 2005: The effect of diurnal correction on satellite-derived lower tropospheric temperature. August 11, online at http://www.scienceexpress.org.

Santer, B.D., et al., 2005: Amplification of surface temperature trends and variability in the tropical atmosphere. August 11, online at http://www.scienceexpress.org.

Sherwood, S., J. Lanzante, and C. Meyer, 2005: Radiosonde daytime biases and late 20th century warming. August 11, online at http://www.scienceexpress.org.