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.
As some of you will know I am unmangling the pyrgeometer data from the fictious “downwelling” IR to the real thing measured, actual thermal flux. This is an approximation based on air temperature and seems to work reasonably well. There is no data for the actual body temperature of the instrument which is mounted some way above the ground, as it seems is the air temperature sensor. All we have so use it.
The big issue is that few of these instruments around the world tell the truth, same for pyraneometers reading light level. Both ought to be full differential devices also sensing flux emitted from the ground cover and reflection from ground cover.
What can be deduced about the thermal radiation balance at 61N?
I extracted a full set of radiation data from the files here, plotted see figure 1.
A very obvious and simple thing to do is take the average of both data and from that a rough estimation of the thermal flux balance is trivial.
| . | Min | Max | Average |
|---|---|---|---|
| Sunlight | 0.07 | 1242.16 | 142.38 |
| Sunlight_24hr [2] | – | – | 135.46 |
| IR_flux_outbound | -7.6 | 124.98 | 43.8 |
We don’t know the reflectance of the surface, not measured. A web trawl suggests a figure around 0.3 for land 60N (clarifying, means 70% absorbed, 30% reflected) but is highly variable and this is the ground, not the atmosphere or clouds.
| . | Watts_sq/m |
|---|---|
| Inbound_*0.3 | 94.82 |
| net_(less_IR) | 51.02 |
So over that time period there is very roughly 50W sq/m available to raise temperature of the ground etc. and evaporate water for transfer away as phase change latent heat or produce convection.
This is plausible, right ballpark.
1. Data processing involves a lot of complex scripts, is dealing with daily compressed archives and a directory structure. Daily results have to be compiled from the images, everything filed into the correct places, and all done minimising input from me. Some of the plots are autoscaled, OCR is not really practical so I have to view the new files and edit the daily configuration, then set the rest of clockwork running.
One day is missing.
2. compensated from 22hr 50m to 24 hours since sunshine in the hour before midnight is unusual.
For IR it is reasonable to assume this period is average.
3. I could upload the data, ask if you want it.
Post by Tim Channon
Tallbloke's Talkshop 
Important research. Well done.
Fig. 1 shows clearly that that the IR measurement follows the incoming sunlight in size and is delayed slightly in time. It is on average 1/3 of the incoming sunlight in Wm-2
44Wm-2/135Wm-2 = 0.3
Land at 60N, on average, absorbs 0.3 of the sunlight
The pyrgeometer is measuring surface reflected IR and not down dwelling IR, DWIR.
I don’t really understand what you’re trying to achieve. Are you trying to quantify how much heat is being transported into/out-of 61N by air movement?
Land at 60N, on average, reflects ( not absorbs) 0.3 of the sunlight
Understanding.
What can be deduced?
Well our belief that the 1361 W/m^2 is reduced by 30% prior to arriving on at the surface is in doubt if the 1242 max you have recorded. And at 61N is even more surprising. Given let’s say 40 degrees off the position of the sun it should be about 730 max. I don’t doubt the reading, but how can it be explained.
mkelly, a simple explanation is here,
A crazy thought just came to mind about the excess insolation from cloud.
Odd things happen during a solar eclipse. Here is a 2011 article, the headline originating in part of the subject, one of my articles (Tim)
An interesting solar eclipse graph here.
Note the rate of change of cooling and warming of the atmosphere during the eclipse. They are not the same. My layman conclusion is sunlight has far more effect on air temperature than LWIR from the surface.
Richard, the plot is showing phase lag, time delays, in the simple case the consequence of a thermal resistance into a thermal (heat) capacity. This heat comes back out or goes back in through usually the same route.
Unfortunately temperature is a proxy for entropy, where entropy is the energy level of a thermal mass, measured as temperature (circular). Energy flows in and out, via a finite resistance (or impedance) therefore there is a time lag. Which applies to the thermometer system too.
Somewhere out there will be a wide range of measurements obtained from solar eclipse, an attractive event for field trips.
Tiny change in low altitude clouds could account for the average global temperature change in the 20th century.
Global warming made simple
http://lowaltitudeclouds.blogspot.com/
tchannon says: May 25, 2013 at 4:32 pm
“This heat comes back out or goes back in through usually the same route.”
No it doesn’t Tim. The OLR wavelengths of insolation are absorbed in the upper atmospheric layers. Thus, during an eclipse, surface origin OLR wavelengths are attenuated by the lack of stimulation from the shorter wavelengths of insolation.
For the human observation of ‘colder, but seemed warmer’ during an eclipse. With a sudden temperature drop the ‘relative humidity’ (RH) increases and the human response to this is that body sweat doesn’t evaporate so readily. This promotes a claustrophobic response with the production of more sweat being generated by the skin and can be confused with the human body being presented with a warmer temperature.
Best regards, Ray.
Sorry, I was not making what I meant clear. I was referring to heat flow into or out of a body where that is acting as a thermal capacity.
tchannon says: May 27, 2013 at 4:10 am
Don’t apologise Tim. Whether you look at incoming long-wave, or outgoing long-wave, the energy transfer is NEVER 100% of what you’re looking at. The ‘main attractor’ takes the greatest energy, but there are always ‘losses’ to more ‘minor attractors’. ‘Energy in’ is never equal to ‘energy out’ because these ‘minor attractors’ always take their share of energy when ‘energy transfer’ is evident.
We always find that ‘eta E’ is less than unity. 🙂
Best regards, Ray.