Dunkeswell Aerodrome WMO 03840 – Major Relocation, Misinformation in archives and “Sileage Heating”

50.86016 -3.24014 Met Office CIMO Assessed Class 4 Archived temperature records from 1/11/1979

The Dunkeswell aviation site was originally opened as RAF Dunkeswell in 1943 but was mostly operated originally by the US Air Force. It would originally had its own meteorological equipment but none of its data from those early years have been retained. Archived temperature records start from 1/11/1979 and there onwards a degree of confusion arises.

The current site is not the original location in 1979 despite it being alongside a building described as the “Old Control Tower” – logic would normally assume this would be the first site – back in its pre-archive dates it may well have been. The vestige of the 1979 original recordings site is shown deep into the “Remarks” section of the archives (that few would normally delve into) at grid reference 313800E, 107900N as below.

The above ran as a 24 hour manually reporting site up to 20/5/1991 whereupon it was relocated and simultaneously automated. This move is not shown by renaming nor renumbering despite being a substantial 1.1 kilometres. as detailed below.

A point of major concern is that the digitalised records for all the years back to 1979 only show the coordinates of the current operational site. I feel this is misrepresentation, a modern day student behind a computer screen will neither check any manual records for a location check (as I did) nor would they have any reason to doubt the records. This is not an almost excusable error of omission, for whatever reason, on transcribing the original manuscript the coordinates were changed from those shown on the originals thus a conscious act. This rather calls into question what other “facts” may have been altered on transcription without physically checking line by line.

The above two sites have climatological differences, the 1979 iteration was likely subject to the modern encroachment of new site development which prompted the long distance relocation to the other side of the airfield. This long distance is quite common on airfield sites for example Marham. The two sites readings simply cannot be considered as one continuous record and should be treated as two separate sites, however, this is not indicated so most “studying” the records would have no idea.

Is the new site a good one given the expense of the relocation? It is reasonably rural but does sit in an ever changing agricultural location alongside a tarmac roadway. The real issue is the use of the area for storage. In reviewing Coton-in-the-Elms, commenter “muddyv” raised the following point “Note the large round silage bales stacked on the north of the site not only provide shelter, they also generate heat. The hay grass in the bales ferments and generate considerable heat in the process.”

In the headline image (and throughout lots of google historic images) there are large stores of black Silage Bales to the south west of the Screen. Opting to quantify any effect, I noted these 1.2 metre (4 feet) circular bales are stacked 3 high producing a 3.6 metre (12 feet) high windbreak to the direction from which is the prevailing wind in the UK. This wall of 230 square metres area will unquestionably have an effect of reducing wind speeds in being just 25 metres from the screen. Notably though, following up on “muddyv’s” remark I found some quite remarkable figures relating to “Silage Heating“

I was immediately reminded of Tim Channon’s remarks in his review of Redesdale Camp , particularly “Caution is needed over data from this site without knowledge of near site changes.” In the case of Dunkeswell we have an area that is both a substantial windbreak and a major heat source potentially up to 50 to 60° C at origin. A reduced velocity breeze from the windbreak effect could well pick up fermentation warmth , pass over black tarmac and keep night time minima significantly warmer than otherwise would be natural. A similar effect to that of artificial warming from a heat source at Bingley, Amersham, Cambridge NIAB, Cassley and others.

I asked Dave Woolcock (who supplied analysis for Lerwick) if he could run comparative tests on the old and newer site’s readings in order to quantify and differences between them. Unfortunately (and unusually for an airfield) the data was so partial with hundreds of missing readings that no useful comparisons could be drawn. No only are the sites poor their reading records are equally so.

In summary Dunkeswell is a current unsuitable site for accurate readings that is Met Office rated as Class 4 but I feel the potential transient effects downgrade it to Class 5. Its very poor historic record is a bonding of two different data sets from two distinctly different sets of instrumentation and cannot neither be considered continuous nor reliable. A site to ignore.

Source: https://tallbloke.wordpress.com/2025/05/30/dunkeswell-aerodrome-wmo-03840-major-relocation-misinformation-in-archives-and-sileage-heating/