Maybe not an expected article from me right now but as things turn up…
During a recent cold snap there were at times clear skies and a calm. Here is evidence of a profound difference between Met Office sites when site exposure and UHI thermal mass can upset natural radiative cooling.
The Farnborough site is in my estimation WMO Class 1 whereas RHS Wisley is poor, in an orchard designed to make a microclimate. Wisley however has been cited in literature and government chambers (and by Phil Jones) in relation to UHI in comparison with a record setting London site, specifically a site I have omitted from the surfacestation work. Overloaded with too much information.
Intended to be a fair encirclement.
The night of 29th to 30th December 2014 is most telling.
Farnborough which is still somewhat an urban area cools more effectively, Charlwood a little less so. The others are much worse, 2 to 4 degrees C.
Under other conditions there is generally less difference. I’ll include a spreadsheet with all the data I have if anyone wants to investigate other dates and parameters. (runs from 22 July)
There will be minor time delays between these sites, including dawn and dusk, and from air movement.
Food for thought is how strongly the wind follows the sun, airflow dominates, smothers radiation.
A word on Charlwood: the site was poor, palleted equipment site with the screen in effect buried in an unkempt hedge. Recent evidence says the vegetation has been cleaned up.
Averaging the wind data to one trace avoids cluttering the plot and seems fair.
Links to surfacestation articles
Hourly Met Office data from Datapoint under OGL
Map own work from NOAA outline data.
Spreadsheet inside a zip, OpenOffice/Libreoffice format (1.2MB)
(ask if you need help)
Post by Tim
[UPDATE 7th Jan in response to a comment]
Was I wrong to use average wind speed?
Plotting all temperature and wind in one is far too confusing, tried again and failed so here are separate plots.
(added to a post by hand instead of double uploads resized here, click for a clearer view )
KatyD wrote ” The wind speeds in each location were quite different, so averaging the wind doesn’t seem correct. ”
Looks like I was wrong to include Kenley, added last to try and encircle.