31 Don’t forget the yellowing of the plastic that comes with UV exposure. That is one problem that has been noted by the AMS.

Do you have a reference to an AMS publication on this?

That led me to compare MMTS against Minmax. Why, well before a station was switched
to MMTS it was likley a MinMAX in a CRS ( stevenson screen)

So you have a history of CRS stations. At some point they start switching to MMTS
those that remain as MinMAX in a CRS will have the painting Issue. That is, after they
switch paint on a CRS away from whitewash, we can expect a warming relative to MMTS
All else being equal. Thus in the early station historys MinMax and MMTS should look
the same, because MMTS is actually MinMax ( the current variable only has the end
state of the site)

I have to double check some dates with Anthony, But MinMAX and “MMTS” show no difference
until the late 70s. then MinMAx warms relative to MMTS by .2C. change in paint may
be more important than blackening sensor sheilds

“crud on the beehive study” Yeah that’ll make it into Nature

A fitting sequel to your forthcoming “Bats in the Birdhouse”!

Larry, you seem to believe that an aspirated sensor won’t suffer from contamination problems (or perhaps not as much), but I disagree. I would have thought that dust etc could easily collect on the sensor itself – open your PC and see how much dust collects on the CPU heatsink! IMO, this would be worse than a contaminated screen because you are essentially covering the sensor itself in a thick coating of unknown thermal properties, which could easily reduce max reading and/or increase min reading. If MMTS is aspirated AND remote reading (which AFAIK, it is), then the problem (if any) could go unnoticed for a LONG time!

But what would be the effect on nighttime lows? I guess this depends on the emissivity of the dirt versus the white plastic in the long-wave IR spectrum, and might differ with mildew, soot, clay, rust, or egg yolk (per #27!).

Does anyone have an informed guess? Or even actual knowledge?

I surveyed one MMTS in Jennins, LA which had apparently been “egged” ( photo ) .

In case “egging” is unknown elsewhere, it’s an act of throwing chicken eggs at some object, usually by teenagers and usually thrown at something of which they disapprove. I think this MMTS is simply an easy target, being close to a country road.

Dried egg residue does not weather away very well. This stain could be around for a while, unless the curator cleans it.

Score one bullseye for Global Warming!

In case “egging” is unknown elsewhere, it’s an act of throwing chicken eggs at some object, usually by teenagers and usually thrown at something of which they disapprove. I think this MMTS is simply an easy target, being close to a country road.

Dried egg residue does not weather away very well. This stain could be around for a while, unless the curator cleans it.