Wind run looks to be under reading at high wind runs
Posted: Thu 19 Dec 2013 12:47 pm
Firstly this post should be in Cumulus Beta but I'm now locked out and cannot see how to get access again.
Assuming wind run is calculated thus [Average of all the average wind speeds 00.00 to 23.55] x 24 hrs., then the dayfile recorded wind run appears to be under recording.
As you can see from the snapshot below, at low wind runs dayfile 22.0 versus logfile 22.2 / dayfile 30.9 versus logfile 30.9 / dayfile 14.0 versus logfile 14.2. At high wind runs dayfile 117.9 versus logfile 131.6 / dayfile 126.6 versus logfile 145.7.
Initially I couldn’t see why this might happen. Then I realised that at low wind speeds when applying the wind speed multiplier to e.g. 1, 2, 3, 4 mph then when rounded to produce an integer the mph value remains the same as the original value. It’s only at higher wind speeds that the multiplier adds to the original value. This is the only reason I can see why dayfile versus logfile are close/spot on at low daily wind speeds, but the higher the daily wind speeds the higher the discrepancy. To summarise, either I've misunderstood something or it looks like the wind multiplier is not being applied during the wind run calculation.
PS At present I don’t run cumulus 24/7, I download data once a week. Not sure if this could be the problem.
Colin
Assuming wind run is calculated thus [Average of all the average wind speeds 00.00 to 23.55] x 24 hrs., then the dayfile recorded wind run appears to be under recording.
As you can see from the snapshot below, at low wind runs dayfile 22.0 versus logfile 22.2 / dayfile 30.9 versus logfile 30.9 / dayfile 14.0 versus logfile 14.2. At high wind runs dayfile 117.9 versus logfile 131.6 / dayfile 126.6 versus logfile 145.7.
Initially I couldn’t see why this might happen. Then I realised that at low wind speeds when applying the wind speed multiplier to e.g. 1, 2, 3, 4 mph then when rounded to produce an integer the mph value remains the same as the original value. It’s only at higher wind speeds that the multiplier adds to the original value. This is the only reason I can see why dayfile versus logfile are close/spot on at low daily wind speeds, but the higher the daily wind speeds the higher the discrepancy. To summarise, either I've misunderstood something or it looks like the wind multiplier is not being applied during the wind run calculation.
PS At present I don’t run cumulus 24/7, I download data once a week. Not sure if this could be the problem.
Colin
