There's not going to be any significant difference between 2m and 10m.
A better question might be why they are measuring temperature there on a hot roof and not over grass. According to NOAA, that's a Class 5 location (the worst):
Class 5 (error ≥ 5ºC) – Temperature sensor located next to/above an artificial heating source, such a building, roof top, parking lot, or concrete surface. (Section 2.2.1 of the U. S. Climate Reference Network Site Information Handbook)
Edge effects are a massive thing in fluid flow. I'd expect there to be a significant difference between air quality at ground level (human mouth level) and 2nd-storey level. Isn't the turbulent flow around ground obstructions likely to make more pollutants gather in the boundary layer, and the lower flow rate ensure they're not swept away? (I don't know the answer, I'm asking a question to check my intuition)
The cylindrical unit half way up the pole and to the right with the louvres is a solar radiation shield that would be typical for containing a thermometer and possibly a humidity sensor - the louvres let the air through without letting direct sunlight hit the thermometer and throw off its reading.
But I’m sure they aren’t using it as a calibrated value (obviously they would have guidelines for placement and would know this doesn’t meet them), it’s probably just being used as an indicative reading.
I'd assume (maybe wrongly) proper air measurement would require some adjustment for things like density based on altitude, temperature, etc so there's a standard to compare it to.
A better question might be why they are measuring temperature there on a hot roof and not over grass. According to NOAA, that's a Class 5 location (the worst):
Class 5 (error ≥ 5ºC) – Temperature sensor located next to/above an artificial heating source, such a building, roof top, parking lot, or concrete surface. (Section 2.2.1 of the U. S. Climate Reference Network Site Information Handbook)
http://www1.ncdc.noaa.gov/pub/data/uscrn/documentation/progr...