How to calculate average yearly windspeed?

[jwwd]

Hi

I got a message from one of my visitors of my website. He ask about the yearly average windspeed (2,1 m/s served by WD) which he finds a bit in the low end. I might agree with him - it dosent sound of much.

Now I would like to calculate the average windspeed myself from the WD logfiles (1-minute interval)

I have all my WD logfiles exportet to Microsoft Excel Spreedshet.

Can I just take every 1-minut windspeed and divede to the number of lines? Or should I do that per hour/day/month?

Best regards,

Henrik

[administrator]

If you just want the yearly average, add the values and divide by the number of lines. If you want other averages, then you'd need to do months, etc.

[jwwd]

Hi

I have managed to get all my WD logfiles in one Excel Spreadsheet for hole 2011 (523,102 rows. I miss about 2,498 1-minute rows on a hole year - not that bad  Thanks to Windy for a GREAT program )

I have found the average values.

Now I got a question about windspeed - what would be the correct average windspeed for the hole year?

Total of windgust diveded by 523,102 rows (gives 3.9 knots)
or
Total of average windspeed diveded by 523,102 rows (gives 6.6 knots)

Best regards,

Henrik

[Weather Display]

in WD, go to view, av/ext
then set the year
then click on year to date
then you should see the average windspeed for the whole year
do that for other years and note them down then manualy calculate the average from each of the those years
try that

[jwwd]

Hi Brian

My calculations in the BIG Excel Spreadsheet with all logfiles for 2011 match excactly to the average windspeed and average windgust calculated by WD.

I just dont understand why average windspeed is 2.0 m/s and average windgust for hole year (1-minute interval) is 3.4 m/s - what are the difference? Sorry for asking dumb questions - but would all windgusts diveded by all the rows not give the average windspeed?

Hope the above makes sense?

Best regards,

Henrik

[kimhumpries]

Take your anemometer out into the wind. Hold it above your head, but where you can still count the number of rotations.

[Budgie]

I just dont understand why average windspeed is 2.0 m/s and average windgust for hole year (1-minute interval) is 3.4 m/s - what are the difference? Sorry for asking dumb questions - but would all windgusts diveded by all the rows not give the average windspeed?

The average windspeed is measured over minutes (10 min my case), where as the gust is measured over a few seconds.
If you use the windgust for the yearly average then you're only measuring the peaks, not the actual average.
Eg: Take one line in the data; the current 10 minute average is 3m/s but in the last minute you've had a gust of 10m/s. Which will give you the more accurate yearly average?

[jwwd]

The average windspeed is measured over minutes (10 min my case), where as the gust is measured over a few seconds.
If you use the windgust for the yearly average then you're only measuring the peaks, not the actual average.
Eg: Take one line in the data; the current 10 minute average is 3m/s but in the last minute you've had a gust of 10m/s. Which will give you the more accurate yearly average?

Hi Martin

Of course - you are right. Thanks for the explanation.

Best regards,

Henrik