D
Don Klipstein
Guest
In article <gg1gj51qqupdi1rskr6g7cq0j5n1p2stb5@4ax.com>, John Larkin wrote:
-
I did not see anything there on infrared spectral properties of
thermistor-based sensors, or anything leading to any reading material on
such.
You did provide two links. One was a powerpoint presentation on
radiosondes, that I consider practically a smallish book on radiosondes -
but I saw nothing on IR spectral properties.
The other resolves somehow to or fails to work:
http://www.wmo.int/pages/prog/www/IMOP/meetings/Upper-Air/
Systems-Intercomp/Doc3-1(1)UKMetO.ppt
One thing that did say was that "solar heating introduces significant
systemic errors, difficult to correct, at pressures lower than 100 hPa.
If that is hectopascals, that is about 1/1000 of sea level atmospheric
pressure, or roughly 1 millibar. That is upper stratosphere.
Next several pages show a variety of deviations, including a calibration
problem good for reading half a degree high for most units from 1989-1991.
Another problem was a correction factor failing to adjust downward due to
cloud cover, causing output to be erroneously high.
There was a recurring "theme" of infrared problem being a thermal IR
one, where the sensor radiates thermal infrared - generally cooling it.
One page mentioned error caused by IR emission and absorption at the
specific pressure of 10 hPa (approx. 10 millibars, middle to upper
stratosphere) - the sensor was cooled by its IR properties in air warmer
than -66 degrees C, warmed (I guess by receiving thermal radiation) if it
was in air colder than -66 C. At 32 hPa (middle stratopshere), the
sensor's "equilibrium temperature" was -62 C. At 200 hPa (roughly
tropopause), the "equilibrium temperature" was -56 C, and error due to
IR radiation was much smaller.
If/where the same type of radiosondes were used throughout a large time
stretch, say from 1991 to 2005, then warming they show in the lower
troposphere is real.
Meanwhile, I do suspect that the UAH and RSS crews are aware of these
factors when they do whatever calibration/recalibration to radiosonde data
they do, especially considering UAH would prefer to not have to report a
warming trend.
- Don Klipstein (don@misty.com)
I think I found your earlier posting on radiosondes with that message-IDOn Sun, 27 Dec 2009 23:37:08 +0000 (UTC), don@manx.misty.com (Don
Klipstein) wrote:
In article <en5fj5hee89bihqoqcnt28vd1e0qh6rnac@4ax.com>, John Larkin wrote
in part:
I've done a little reading up on radiosondes... I used to buy surplus
ones when I was a kid, so they interest me. There's some interesting
stuff about the IR absorption of the "white" thermistor capsules that
are generally used these days. They tend to - surprise, surprise -
read high.
What sort of IR absorbtion do these have, then?
Google does not turn up anything on:
radiosonde "thermistor capsule"
radiosonde "thermistor capsules"
And if they read high, would they not also read high in the levels of
the atmosphere *cooled* by greenhouse gases?
- Don Klipstein (don@misty.com)
I posted on that before:
Message-ID: <if23j5h87ul9lfsr97m0n6ue1ck3giijl2@4ax.com
but goodling radiosonde thermistor accuracy
works better.
Apparently radiosonde temperature measurement gear has changed a lot
in recent years, and the dreaded "corrections" are still under debate.
Radiosonde data is one of the confirmations often cited to justify
other (corrected) AGW temperature-rise data. It would be remarkable if
it turned out that radiosonde data is incorrect or improperly adjusted
such as to agree with other incorrect measurements. Stranger things
have happened.
Measuring air temperature turns out to be non-trivial. I'm currently
waiting for the epoxy to set on a thin-film 1K platinum RTD, at the
end of a spool of RG-174, potted into a piece of soda straw. That will
go into a niche on the north side of the cabin.
-
I did not see anything there on infrared spectral properties of
thermistor-based sensors, or anything leading to any reading material on
such.
You did provide two links. One was a powerpoint presentation on
radiosondes, that I consider practically a smallish book on radiosondes -
but I saw nothing on IR spectral properties.
The other resolves somehow to or fails to work:
http://www.wmo.int/pages/prog/www/IMOP/meetings/Upper-Air/
Systems-Intercomp/Doc3-1(1)UKMetO.ppt
One thing that did say was that "solar heating introduces significant
systemic errors, difficult to correct, at pressures lower than 100 hPa.
If that is hectopascals, that is about 1/1000 of sea level atmospheric
pressure, or roughly 1 millibar. That is upper stratosphere.
Next several pages show a variety of deviations, including a calibration
problem good for reading half a degree high for most units from 1989-1991.
Another problem was a correction factor failing to adjust downward due to
cloud cover, causing output to be erroneously high.
There was a recurring "theme" of infrared problem being a thermal IR
one, where the sensor radiates thermal infrared - generally cooling it.
One page mentioned error caused by IR emission and absorption at the
specific pressure of 10 hPa (approx. 10 millibars, middle to upper
stratosphere) - the sensor was cooled by its IR properties in air warmer
than -66 degrees C, warmed (I guess by receiving thermal radiation) if it
was in air colder than -66 C. At 32 hPa (middle stratopshere), the
sensor's "equilibrium temperature" was -62 C. At 200 hPa (roughly
tropopause), the "equilibrium temperature" was -56 C, and error due to
IR radiation was much smaller.
If/where the same type of radiosondes were used throughout a large time
stretch, say from 1991 to 2005, then warming they show in the lower
troposphere is real.
Meanwhile, I do suspect that the UAH and RSS crews are aware of these
factors when they do whatever calibration/recalibration to radiosonde data
they do, especially considering UAH would prefer to not have to report a
warming trend.
- Don Klipstein (don@misty.com)