On 19 Dec, the first anemometer (H1:PEM-X_FENCE_WIND_SPEED_3) behind the fence was lower to 2'AGL (above ground level.)  We want to know what the wind does in the gap between the ground and the bottom of the fence which is at 4'AGL; it is possible the wind could be accelerated in the gap.

Based on the data looked at this morning, the wind is not accelerated in the gap.

Attached are two graphs each with 5 plots showing the wind direction; and, the velocity at 4 locations, see location sketch here.  On three of the speed plots are copies of another location's wind speed (in green); and, in blue, manipulated data as indicated in text.  The blue trace scales from 0 to 10 for 0 to 100% speed reduction.  Were there a velocity increase, the result would be negative.

The first attachment is from 15 December, a few days before the anemometer was lowered.  The wind direction during these 10 hours was okay at worse being maybe 40° from our nominal 90.  The upper left plot shows that there is a reduction of about 10 to 20% from the far field sensor to the unit 10' up-stream of the fence.  The two right plots indicate that the fence is reducing the wind velocity about 45 to 60% with speed_4 showing the 60% reduction at 20' downwind compared to just 45% at 10' downwind, interesting...

The second attachment is from December 29/30 when for 12 hours the wind was strong and about in the right direction.  Again a similar reduction at the upwind sensor relative to the free stream.  The two right plots show the difference with the Speed3 lowered,  While the Speed4/Speed2 ratio is still ~60%, there is only ~10% reduction down in the gap at Speed3.  Note--10% reduction, no increase seen in this data set.

Caveat, two different data sets, different wind speeds and directions.  But, given the reductions seen, especially further downstream at Speed4, I'd say the reduced reduction and no increase in Speed3 is legit.  Will look at reasonably oriented stronger winds when they occur.