UKC

https://www.thebmc.co.uk/idwal

Click on the 850m button. The 30cm reading shows a couple of sudden jumps. Not only would I not expect turf to change temperature so quickly, there's no obvious causes, and no corresponding changes at 15cm or 5cm. So the input of heat would have to have come from below.

Does anyone have any thoughts? Is it possible that there's something interesting going on with groundwater beneath the surface? Or is it most likely just a dodgy detector?

In reply to Trevers: See the stop peeing on the footpath thread?

In reply to Trevers:

Idris fly past.......?

In reply to Trevers:

Wombles on holiday?

In reply to Trevers:
When the ground is not insulated by snow I'm not at all surprised to see such jumps. Prior to the last show fall you could see similar also. Ground can cool down pretty quickly when its exposed or heat up very quickly when cold and mild wet rain falls on it.

In the graph you can see the air detector also following the same pattern and the detectors at different depths so its highly unlikely to be a fault IMO.

Its also worth bearing in mind you don't need to go that far down for the earth temperature to be fairly stable all year around so if the top layers are freezing its not going to actual travel that far down in to the soil in the UK normally.

In reply to CurlyStevo:




All good points and makes sense. However the 30cm plot does look odd. There's one spike at 8.00 am. on Saturday. The air temperature has risen fast but there's no response from 5cm and 15cm for a few hours. Then there's another one at lunchtime today (sudden spike, gentle falling limb) which doesn't correspond to any rise in air temperature or other turf temperatures.

In reply to Trevers:

if the raw data from the field is being transmitted / received then not filtered for possible interfance then there are going to be spikes in the data.

maybe someone from the bmc team can elaborate?

HTH Davey

In reply to Trevers:


Sun-warmed melt/groundwater flowing past at that depth? Could be many things.

In reply to Trevers:

Yeah sorry I didn't think you meant those small blips was looking at the bigger picture.

In reply to Trevers:
Thanks for pointing this out - I'm not sure what the cause might be. It certainly does not seem to follow the "smoother" profile that's normally seen for the 30cm turf sensor. From the previously recorded readings it seems that usually the 30cm sensor provides the "smoothest" graph-line, as expected really - with turf at depth taking longer to cool down/freeze but staying cooler for longer.
Unfortunately I'm too busy with various meetings in other parts of Wales and the UK to get up there myself in the next few daysbut will see if one of the other organsiations involved in the project can have a look.

Elfyn Jones (BMC Access & Conservation Officer Wales)

In reply to Trevers:

Could well be a precipitation event. Warm water drains through the upper turf and through at lower levels, giving the temp spike.

In reply to Elfyn Jones:

Thanks - I'll be really interested to hear what the cause of this might be, whether it's a faulty detector or a data processing issue, or a genuine physical effect.

It's a really useful resource. If you change the view to 30 days, you can clearly see periods of snow cover and periods without from the responsiveness of the turf temperature readings to air temperature.