Figure 1
Since mid February 2013 I have been capturing high time resolution data from the Chilbolton Observatory web site, done for the previous day. This is processed from .PNG files into numeric data here. [1]
Data exists for about 23 hours a day at a few minutes between samples, data currently amounts to about 56,000 readings.
Sometimes the sun shines through, reflects off and other optical effects of cloud. This does lead to insolation well in excess of the maximum for the time of year. An instance is shown above complete with an hourly sky thumbnail which almost caught one at the time, the effect comes and goes very quickly.
Fyvie Castle, Aberdeenshire, Scotland. A National Trust property, web site entry
57.442805° -2.389692° Google browser map
Altitude 55 metres
AWS since 1994, manual data record from 1959
Estimated Class 4, fails Class 3 on ground cover within 10 metres. (to WMO 1046, 2010)
UHI, microclimate, in a garden. Distance, none.
I need to add I have a close lat/long but no cross reference images or other information so I might have incorrectly located the Stevenson screen.
What follows shows nothing new but is food for thought given the matter of pyrgeometers on the Talkshop.
Figure 1
1st May was a particularly sunny day in southern England but cool, with a continuing wind from Norway via the North Sea.
Red line and arrow, line of sight for Google Streetview, see below.
Killowen, County Down, Northern Ireland, Killowen Outdoor Centre, Carlingford Lough.
Data from 1997, as AWS from about 2000, older data somewhere near from 1961
24 hours ending 2200 on 27 Apr 2013:
UK Highest max 0900-2100 12.9 °C Killowen
54.076877° -6.184006° Bing maps, Google maps
Altitude 4 metres
Estimated Class 4, fails Class 3 on > 10% “Ground covered with natural and low vegetation (<25 cm) representative of the region;” and “at more than 10 m from artificial heat sources and reflective surfaces (buildings, concrete surfaces, car parks, etc.)” with 10 metres. (hedge / wall)
UHI, local, isolated marina, heated public centre, vehicle parking, signs of outfall close to lough edge. Distance, none.
Writtle, Essex. (at Writtle college, just west of Chelmsford)
Records marked from 1940 but the location then not known.
Recent conversion to full AWS 2009.
51.733441° 0.429085°
Altitude 32 metres
Estimated Class 4, fails Class 3 on “Ground covered with natural and low vegetation (<25 cm) representative of the region;” within 10 metres. As a secondary station this seems hard but a ploughed field some of the year is inconsistent.
UHI moderate, housing to south and south west, agricultural college with glasshouses to north, edge of large town of Chelmsford 1.2km, centre 2.7km to the east.
Altnahinch Filters, County Antrim, Northern Ireland
55.047836° -6.255353° Google browser map
Altitude 213 metres.
Estimated Class 4, fails Class 3 on road and sewage tank within 10 metres. Suspect shadow from trees and hill to south west as well. (see Google Streetview below)
UHI, perhaps local sewage works, otherwise none.
This drawing shows the basic internals of a simple passive pyrgeometer.
Heat flows from roughly earth ground temperature into the body, finds it’s way through the body to the underside of the thermoelectric generator, then through that and for a clear sky then radiates from the top side to space, unless there are heavy clouds or it is raining.
I repeat, heat flow is from the ground upwards. (under very rare meteorological conditions a minor reverse flow happens, the former is overwhelmingly dominant)
This is far from the whole convoluted story, which I will now try and explain. In reality it is very simple.
Image dated 2002. Various web sites show the site remains similar. New bedding 2005 and various other detail change. Brochures include site drawing showing a rectangle which is the met. enclosure.
Twice hottest place in UK April 2013 (that I noticed, don’t check every day)
Myerscough, Lancashire,
Myerscough College, Garden Centre and Arboretum
http://www.myerscough.ac.uk
53.8538 -2.7668 Bing maps, Google maps
Altitude 14 metres
Estimated Class 4, fails Class 3 on “Away from all projected shade when the Sun is higher than 7°”, trees to south-west and west. Poor exposure.
I suspect it ought to be Class 5 but estimating shadow without more certain detail is impossible.
It is a microclimate.
UHI, local, distance, minor.
Courtesy Physikalisch-Meteorologisches Observatorium Davos
Radiation instrument with cover removed
Since I have just made available numeric data which will add meat to talk about pyrgeometers and how heat behaves and travels in the atmosphere, a continuation of a long Talkshop thread can take place here. If you want to comment on what the Chilbolton data means, then this is the thread.
Original thread is here.
