This study by Hubbard et al shows the results of extensive test of MMTS, CRS and GILL shelters. A later study published in 2004 indicated that there is a 0.3 to 1.0 warming bias in the MMTS measurements. I can’t find the URL but it was an AMS published article. this error could be due to aging of stations (yellowing). Karl et al. published a paper (late 1990′s?)stating that a -0.3 to -0.7 degree error was associated with the MMTS system.

The Hubbard study indicates to me that the error varies with region and season. One study that I cannot locate was by Thomas Blackburn. He maintained a fair number of in situ co-located MMTS and CRS sites. The only co-located site I could find was Ft. Collins CO.

THE ISSUE is this. was the MMTS study broad enough to capture other effects
from switching to MMTS.. Namely moving close to buildings.

The Point is the MMTS adjustment needs to be audited. IF switching to MMTS
gives cooler temps for the same location ( as in the study) FINE. Adjust
the record. But if the study was not broad enough, or long enough ( all seasons)
then the MMTS study needs a revisit.

Its Not the adjustment. Its the magnitude and the manner of the adjustment.

I think the issue is this. UHI ( urban heat Island ) is known to Corrupt
TMIN: the minimum temp f the day. So Assume TMax = 10 and Tmin = 5.
TMEAN will be (10+5)/2 = 7.5

Now assume that Microsite issues ( asphalt ) are a Subspecies of UHI.
( they are) So, lets say that the Ashphalt currupys TMIN. TMIN is raised
3C

SO TMEAN = (10+8)/2 = 9C. SO a 3C effect is diminished to a 1.5C effect.

Then we also knw that UHI is strongest in warmer months ( more on this latter)

So this 1.5C effect happens for 33% of the year. So this effect is Now .5C.

Then we als knw that clunds and wind can modulate this… So we lose 50%
of .5C.. and we are down to a .25C effect.

THEN, that .25C effect shows up OVER TIME.

I’m hinting at some work I’ve done with JohnVs model and differences between
class 5 and class 1&2.. AS A FUNCTION of Season.. First cut only…

Others are welcomed to look. Look fr microsite bias in seasonal differences between
CRN12 and CRN5..

And lots other things as well. Parking lots, concrete pads, air conditioner units, diesel generators, trash burn barrels, chimneys.

For many of these sites, they have been degrading over years, sometimes decades. 5 degrees spread out over 20 years doesn’t leave very many big jumps tin the record.

That would be rare, but there seems to be a definite warming error in the MMTS shelters under high solar irradiance provided there is no snow on the ground for some odd reason.

That makes me wounder why it has a warming correction?

i have no idea. but the 20°C argument is based on a very bizarre situation (sunlight hitting the heat sensor DIRECTLY.)

That’s only if all of the development occurrs at once. Typically it’s one building at a time. Each jump is only a few hundredths of a degree.

how many buildings do you want to build around the sensor????
again, why not hear more about those “few hundredths” and less about the 5°C thingy?

i really like the notion of a 10 to 20% difference between GISS and type12. my guess is slightly lower, but i think those are reasonable numbers!

lots of people with zero understanding are following these discussion, then run away with a completely useless set of numbers on their minds.

Now, let’s figure out where to find the raw data so my results can be updated if needed.

John, i have immense respect for the work you do and how you do it!

I absolutely apologize for the tone of my last post.
I should know better than to post at the end of a long and frustrating day.
Now, let’s figure out where to find the raw data so my results can be updated if needed.

2) Assuming that, before 1920, the site had no asphalt, no AC, and no sewage treatment plant (reasonable assumptions, I believe), couldn’t we eliminate pretty much all of these microsite issues by setting up a temporary thermometer site with similar equipment (even if only for a day in a couple of seasons, or much better for a year) in the open field about 400 feet to the southeast of this site, and comparing the readings (at least for days without wind from the NW)? We wouldn’t know exactly when the microsite skew occurred, but we would know its magnitude for the recent period vs. the 1900-1920 period. And shouldn’t the government be doing this with at least several such sites, to see if their microsite adjustments are reasonable?

You can see how the different versions relate to one another in this chart.

http://www.ncdc.noaa.gov/img/climate/research/ushcn/ts.ushcn_anom25_diffs_pg.gif

In terms of how each version’s adjustments add to the overall trend since 1900 in temperature:

- TOBS adds 0.35F to the RAW data

- MMTS then adds 0.05F to TOBS

- SHAP then adds 0.25F to MMTS

- FILNET then adds 0.1F to SHAP

- FINAL reduces 0.1F from FILNET

Needless to say, it is hard to believe that almost all the adjustments add so consistently to the trend. This cahrt stops in 2000 and we know there has been more changes in the trend post-2000.

Now add some Hansen GISS adjustments to this and what do you get? Global warming.

John V. use the RAW data so we can see if there really is some difference betwen CRN 1,2, and 5 stations before all the variation is adjusted out by global warming adjustments.

A suggestion…

is there someone who can maintain some type of a racing form or scorecard that maintains and explains the datasets in play and each of their incarnations? The folks working with them have been frequently confused and the visitors and lurkers are hopelessly lost. It will almost certainly pay dividends down the road for data users and the audience watching the spectacle of the dataset morphing unfold.