Figure 1
RAF Valley has an international climatic meteorological station run by the UK Met Office.
[ update
53.25267670440459,-4.53652739944032
Standard enclosure base layout, paving, at best Class 3, see Llanbedr article ]
This is the first time I have attempted to classify a site to WMO Class standard. These run good to bad, 1 to 5 for temperature and humidity measurement.
WMO-03302, Valley is Class 3, is degraded by 21% of a circle radius 30 metres being covered in hard taxiway. Class 2 states <=10%
Figure 2
“Class 3 (additional estimated uncertainty added by siting up to 1°C)”
Valley (on island of Anglesea, North Wales) has an Atlantic maritime climate. Would be a good representation of such a location if only it was Class 1. Met Office page for this site http://www.metoffice.gov.uk/weather/uk/wl/valley_forecast_weather.html
The Latitude and longitude given is very close to accurate. For those who need more bing
http://www.bing.com/maps/?v=2&cp=sw7wzrgmnrrb&lvl=17&dir=0&sty=b&form=LMLTCC
A huge further problem is the unknown changes in history. Almost certainly the site has moved. Most likely it was close to the original control tower.
There is more to this but enough for a first step.
How have I done this?
This might be the start of a European station audit where I have a lot more words to say later.
What matters here is practicality.
Firstly we need a ground aligned photo which mostly means using GE (Google Earth) as well obviously as knowing the location of the Stevenson screen.
GE can flat align so you are perpendicular to the ground. It also has what seems fairly accurate geometry and the measurement tool is our friend.
As a sanity check if possible find a known object somewhere in the vicinity of a met site and measure it.
Now centre on the Stevenson screen and measure a line from there 100 metres long, zoom and pan as necessary so that a screen capture of a 100 metre radius circle can be grabbed. Move the measure box out of the way as necessary so we have a good view.
Get the screen grab into an image editor (via a file if necessary) and crop sensibly, save to a .jpg
Figure 4
Here is one I prepared earlier.
Draftsight
Draftsight is an enhance clone of the venerable Autodesk autoCAD 2D drawing package but written by Dassault Systems, associated with the authors of Solidworks 3D drawing and modelling software. Twist is this is completely free other than needing to register and accept emails.
It is full blown professional CAD. Windows or Linux or Mac. (BSD presumably with Linux emulation)
For those of you not familiar with CAD we tend to work with one hand on the keyboard and one on a mouse, tablet or whatever. Is about efficiency, ergonomics. (a full menu GUI is there as well)
Drawing up the WMO circles takes a few moments. such as c {click} r 100
In fact I used a template ready drawn and inserted a background image prepared earlier as above. Move the image to behind the circles.
Now for the magic.
Measure the yellow line length. For the image scale 100/L
Idea here is scale 100 metres on the bitmap to be 100 units on the drawing (doesn’t matter what units).
With judicious use of snap (to hot point) move {the point pin end of measurement} and {centre of circles}
And there we are.
It’s then a matter of looking and measuring to figure out the class.
Figure 5
I’ve put a crude polygon around the asphalt, blue markers and is a closed figure (snap again). On the left are the properties of what is selected, see the A on a yellow ground? 594.045 which is the area of the polygon. Because the circles were drawn to a decimal scale the whole thing is ratiometric.
Area of the 30m circle is 2827.433
100 x 594/2827 = 21%
There are a zillion other ways to do this with this software or other packages and method, such as pixel work. Whatever works but preferably so that a proof picture can be made available. Doesn’t have to be GE either.
Reference
Draftsight http://www.3ds.com/products/draftsight/free-cad-software/
about 90Mbyte, is not particularly in need of fancy hardware, if you can use GE, this will be no problem.
“World Meteorological Organization Commission for Instruments and Methods of Observation, Fifteenth session, (CIMO-XV, 2010) WMO publication Number 1064, available online at: http://www.wmo.int/pages/prog/www/CIMO/CIMO15-WMO1064/1064_en.pdf “
– http://wattsupwiththat.com/2012/07/29/press-release-2/
Linkback Surface Stations Project
post by co-moderator
Yowza. CAD re-purposed; very nice work!
You forgot the blob at the bottom, rectangle in the middle and the paved pathway.
I raise your 21% to 27%
Any idea why the weather is an official secret at Camborne?
http://goo.gl/maps/csQ25
It’s grass John, been mown differently around a mast of some kind. Thank you for pointing this out because it gives a useful discussion point.
There is the concrete (likely) covered ducting too, but it is much better to understate when telling awkward stories for someone because they will try and kick back. Up to ~12% would be marginal. I make mistakes so checking me is good.
The grass.
If you use the Google Earth image history facility you will see a Hawk trainer with vapour trail (I think it is Hawk) flying past and various vegetation states and representations of the ground. If you look at figure 4, I’ve deliberately kept the image date in view, if barely legible
I think it is grass.
Caz. In the past when I have been heavily using these image facilities I found outages when images were being updated, etc.
I already have the Cambourne site 50.218339° -5.327571°
Keep watching, a sub-site at the Talkshop where things can be put might to appearing. If nothing else this tries to keep this stuff out of the way of other things.
I didn’t mean the location which does also seem to be an official secret as the address does not appear to be published anywhere, but I meant the sign on the gate. ” This is a prohibited place within the meaning of the Official Secrets Acts.”
http://goo.gl/maps/csQ25
I’d never been able to locate the Camborne weather station which is actually at Kehelland until I came across the Geograph site. Even the sign at the end of the lane up to the station is not very informative. It’s actually a very large station with state of the art instrumentation and a dedicated balloon launch building so it does seem odd that it was so hard to find.
http://www.geograph.org.uk/photo/2699838
” This is a prohibited place within the meaning of the Official Secrets Acts.”
Met sites are owned by the MOD aren’t they?
“Naff off, you can’t come in here, it’s ours.”
Even more of a problem at Valley would be the hot jet efflux wafting over the sensors as jets taxi past.
Snooping around RAF bases, you’ll get your collar felt. I expect they already know where you live.
JohnG.
people would be surprised at the falloff in air temperature after exhaust leaves the engine. You can search around and find the operating manuals or instructions to airports for safety of ground crews. Engine exhaust velocity and engine air temp are both measured and modelled. For example for some large airliners with wing mounted engines the exhaust temperature is almost at ambient by the time the plume reaches the tail. It also probably depends on the bypass ratio of the engine.
Some might be Steven but keep in mind there are widely experience engineering types around.
Been around engines much? Been in places the public are not allowed because what you write suggests not.
I doubt direct exhaust heat is much of an issue but that has to be on a case by case basis.
There is widespread miscomprehension of heat engines. In this kind of instance there is no suggestion of takeoff conditions (but does apply elsewhere). Both taxi and takeoff are poor thermal efficiency conditions. Bypass ratio if it applies (fanjets, military tends to pure jet) doesn’t really change anything. Taxi? Few % efficiency but low power.
If the engine is burning fuel to the tune of 10MW there is essentially 10MW of loss. Directly warmed air, added water vapour and mechanical energy in the form of motion in a lossy fluid, air, motion which degenerates into heat.
Lots of factors. For example the V2 area there will be ground vectored maximum thrust perhaps with afterburn. Heat injected into the concrete bleeds back out.
Valley is a windy coastal place but we do get periods of no wind, when extremes occur.
Okay, this will do to
http://www.directindustry.com/prod/rolls-royce/gas-turbines-22649-392999.html
This is stationary gas turbine, in this case very large but this is an easy way to quantify energy, aircraft engines are rated differently.
In this case up to 64MW of electricity alternator output drive by the power power turbine. At the efficiency stated that says 150MW input energy as fuel.
In the example the 64MW is taken off site, not the case with aircraft unless they are being accelerated.
This is a lot of heat.
Bloke down the pub says:
August 22, 2012 at 7:37 pm
Snooping around RAF bases, you’ll get your collar felt. I expect they already know where you live.
Not at Valley you won’t. They have a nice car park on the bend in the road past which is often filled with plane spotters using long lenses. The RAF’s response was to stick a recruiting van and NAAFI wagon in there!
There’s also the newish (last 5 years or so) terminal building for Anglesey Airport. Book a flight to Cardiff or IOM and you’ll practically walk past the WMO site on the way to your plane
Ah, the pragmatic response, work and grub.