Had a bit of breeze at my house last night so checking this morning shows indeed we had some breeze last evening that provided a consistent period for inspection.
Found about 20 minutes from 2210 to 2230 pdt where the direction settled down in a favorable direction around 90o; that is, from due west, normal to the fence upwind of the building. The attached 20 minutes of full data show a few things:
* The roof top PEM anemometer, Ch 1 and Ch 3, the fence direction sensor are in agreement to within ~20o. Maybe this needs correcting or possibly the building is influencing the flow direction. This could be evaluated by looking at the difference in direction as a function of direction.
* The PEM roof-top wind speed, Ch 2, seems to be consistently higher than the fence free air speed, Ch 4. This makes sense as the roof top sensor is maybe 20' higher and the building itself may be providing some velocity increase.
* Comparing Ch 4 & Ch 5, the fence free air sensor and the sensor just 10' upwind of the fence, you see a noisy maybe 10 or 15% reduction of velocity--subject to better analysis than my simple point-by-point division (shown in red on the plot with Ch 5.)
* Comparing Ch 5 & Ch 6, the upwind and downwind (of the fence) sensors, the downwind data is clearly smoother and a comfortable 50% reduced compared to the upwind channel. Again, the red trace on the plot with Ch 6 is (1-Speed_4/Speed_2)
Clearly the Tenax fabric is effective and produces about a 50% velocity reduction, at this free-air speed.
Look forward to Elyssa's more thorough and detailed analyses as nice wind events present themselves.
I thought I had noticed, when looking at the trends for this above, that the sensor downwind of the fence had narrower MAX & MINs. Looking at these again, I thought I was reaching as I could not see it clearly in the basic trends. So, I subtracted the MIN from the MAX and plotted that, here, below. Not sure if this is the best way to quantify this observation but it seems a bit informative.
In the attached you see the same span of time as the plot above with the difference between MAX & MIN for upwind (LR) and downwind (UR.) Clearly with this measure, the down wind sensor (Speed_4) shows less range in velocity of the wind compared to that upwind.
