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Daily avg. windspeed

Posted: Fri 27 Nov 2009 8:36 am
by mynameis
How is this calcultated, the daily (and monthly) average speed ?

Yesterday it was a very windy day with a average between 6-12 m/s all day long (not under 6 m/s at any time). In cumulus "This period" I get a daily average speed of only 3,3 m/s and that must be wrong, but i'm not sure. It would be more likely that the value should be in the region of 6-7 m/s.

Re: Daily avg. windspeed

Posted: Fri 27 Nov 2009 8:46 am
by mynameis
If I take the totalt windrun for that day (646 km) and calculted the avg. windspeed from that I get a average value of 7,48 m/s.

Re: Daily avg. windspeed

Posted: Fri 27 Nov 2009 8:58 am
by steve
It's a bug. I cloned the 'this period' code from the 'this month' code, and while I've changed most of it to look at only the dates specified, for the two items which are taken from the monthly log files rather than dayfile.txt - the average wind speed and the number of gale days - I haven't. So it's displaying the values for those two for the whole of the month so far.

But to answer your question, it takes an average of all of the "current wind speed" values in the monthly log file (nov09log.txt) in this case.

Re: Daily avg. windspeed

Posted: Fri 27 Nov 2009 9:39 am
by mynameis
Aha, ok. Then I know

I can report another bug to, the average tempeture is not calculatet with the "correction"s when you download data from unit. The average, in my case, gets 1 degrees (-1 temperture correction in Cumulus) warmer than the acctual temperture reading in Cumulus.

Re: Daily avg. windspeed

Posted: Fri 27 Nov 2009 10:03 am
by steve
mynameis wrote:Can I do like I did with the windrun to get the average ? (calculate the average from the total windrun)
Yes, it's effectively the same thing (but calculated differently, using 1-minute samples). The average (calculated in the same way as the wind run) is also available in dayfile.txt now - I think it may not have been when I wrote 'this month' originally, so I'll probably change the code to use that instead of the values in the monthly log.
I can report another bug to, the average tempeture is not calculatet with the "correction"s when you download data from unit. The average, in my case, gets 1 degrees (-1 temperture correction in Cumulus) warmer than the acctual temperture reading in Cumulus.
Which average temperature?

Re: Daily avg. windspeed

Posted: Fri 27 Nov 2009 10:11 am
by mynameis
The daily, that one thats calculated (I suppose) on a 1 min basis. That one you can see in Cumulus in the "Outdoor" frame "Avg Temp"

Re: Daily avg. windspeed

Posted: Fri 27 Nov 2009 10:38 am
by steve
mynameis wrote:The daily, that one thats calculated (I suppose) on a 1 min basis. That one you can see in Cumulus in the "Outdoor" frame "Avg Temp"
I can't see anything wrong in the code. The 'calibrated' outside temperature is displayed in the 'Temp' box on the main screen, and once a minute that value is added to a running total for the day. The average that is displayed in the 'Avg temp' box is that total divided by the number of samples.

Has Cumulus been running all the time? There may be a bug in the code which handles the average when data is read from the logger.

Re: Daily avg. windspeed

Posted: Fri 27 Nov 2009 10:45 am
by mynameis
Its when I download data from the station when the Cumulus had been turn off for a while. So the problem is when the Cumulus is turned off and when I start it up again and it download data from the station. Then the "avg temp" is not calculated with the "correction" values, it is (i think) calculated from the values from the stations download. Maybe im wrong...?

Re: Daily avg. windspeed

Posted: Fri 27 Nov 2009 10:53 am
by steve
I'll check. But it would help to know what type of station you have?

Re: Daily avg. windspeed

Posted: Fri 27 Nov 2009 11:08 am
by steve
I've found the bug in Fine Offset code... I'll check other station types.

Edit: The same bug was in the Davis and La Crosse code...

Re: Daily avg. windspeed

Posted: Fri 27 Nov 2009 1:23 pm
by mynameis
Ah, thats good. Looking for a update on Cumulus then.