Off the top of my head, the only things that will make the sensors bias cold, would be a plant that partially shaded
the sensor.

In addition to the fact that the sensors should already be shaded: if such a plant were close to the sensor, it would impact the humidity. I’ve seen in recommended by energy convervation folks that while well-placed trees can help shade and cool a home in the summer time, poorly-placed trees will make it more difficult to cool the house.

Maybe someone more familiar with this could give better details, but it seems to me that in such a situation one would see night-time lows higher near a plant than away from it.

http://ams.allenpress.com/archive/1520-0477/86/4/pdf/i1520-0477-86-4-497.pdf

I did make two mistakes in my above reference. It was the April addition, not August, (2005)

and it’s the Bulletin of the American Meteorological Society. Not the Journal.

I haven’t been able to find a copy of the regulations, but every picture I have ever seen of a sensor box has them
standing in an open grassy area. No shade.

Re: 125 and previous posts

CRU is part of UEA hence

http://www1.uea.ac.uk/cm/home/services/units/is/strategies/infregs/foi/

May or may not be some use for getting data out of them.

Off the top of my head, the only things that will make the sensors bias cold, would be a plant that partially shaded
the sensor.

I don’t see this as a cold bias. They should all be shaded. A white box still picks up a lot of solar and IR radiation.

Nordic,

I agree with you 100%, but it is at least worth a shot. You may be lucky enough to get a clerk or student to send you the info.

Earle

Not releasing the details of how they have adjusted and corrected data is one thing, but not even allowing people to see what stations were used and experiment with different assumptions themselves is preposterous.

I was thinking more on the lines of environmental issues.
Anything that decreases average wind velocity in are of the sensor will make it read hotter. Be it a hedge row, or
dust collecting on the vent screens.
The boxes are supposed to be painted pure white, but as they age, the paint starts turning grey, so they have to be
repainted regurally. Concrete or asphalt being laid down in the vicinity of the sensor. Even the adding of lights to
the exterior of nearby buildings can have a small influence.

Off the top of my head, the only things that will make the sensors bias cold, would be a plant that partially shaded
the sensor.

The JAMS article I referenced earlier was rather shocking. The boxes are supposed to be on poles (6 ft tall, I think)
well away from buildings. They had a picture of one that was mounted to the southern side of a building, just a few
feet away from an air conditioner unit. It’s been awhile since I read the report, but my recollection is that of the
surveyed sensors, at some 20 to 30% had environmental problems severe enough, that in the opinion of the authors,
the data from those sites was compromised.

On downloading HadCRU3 into R – ‘ve done this recently and I’ll post up a methodology for retrieving it.

Nordic,

I’m a babe in the woods with respect to these datasets. I haven’t even figured out how to read the HadCRUT3 gridcell data into R. I suggest rooting around the HadCRU web site and emailing them if the info isn’t available.

Luck,
Earle