Hi, Wind speed can be a complex topic. The simple answer to your question *I'm wondering if weewx calculates the average windspeed over 10 minutes* is *yes, it can, but...*. Perhaps an explanation of what weeWX archives and reports and a few points on the SteelSeries Weather Gauges might make it clear.
The WeeWX archive field windSpeed holds the average wind speed over the archive period. This might be calculated from loop wind speed data if using software record generation or received directly from the station if hardware record generation is used. On your install your windSpeed fields would I expect be averaged over 2 minutes, I have a 5 minute archive period so mine is a 5 minute average. Stations that use a 10 minute archive period would indeed have a 10 minute average in their windSpeed fields. The daily summary for windSpeed is just an optimisation holding aggregates and other data on your archive windSpeed data, so they to refer to 2, 5 or 10 (in the examples I cited) average values. That is the data storage aspect of weeWX. The other side of the weeWX coin is the reporting. WeeWX has a variety of tags that allow generation of statistics over some period of time eg $day, $week, $span etc. For windSpeed, $day.windSpeed.avg will give you the average of all of the windSpeed values for the day so far. One could argue that the average of an average is dangerous, though in the case where the archive period is homogeneous the calculation is valid (or if your archive period is non-homogeneous and you are using weeWX 3.7.0 or later with the weighted summaries fix applied the calculation is also valid as the values are appropriately weighted). The $span tag allows calculation of aggregates over a user defined period of time, so $span($time_delta=600).windSpeed.avg would allow you use the average windSpeed over the last immediate 10 minutes in your reports, irrespective of your archive period (of course if your archive period is 15 minutes, or some value that is not a factor of 10, then the resulting value will likely be wrong). When you hover over the wind speed gauge in the SteelSeries Weather Gauges the dialog that shows mentions 'Average wind speed (10min)', this is hard coded in the SteelSeries Weather Gauges (why you would have to ask the author, though I do seem to recall that Cumulus (once? now ?) defaulted to what we would call a 10 minute archive period and the SteelSeries Weather Gauges author is a Cumulus user - I may be wrong). The value that is displayed against 'Average wind speed (10min)' comes from the wspeed field in gauge-data.txt. The gauge-data.txt.tmpl file that is currently included with the SteelSeries Weather Gauges fills the wspeed field using $ hour.windSpeed.avg.raw which would result in the average windSpeed value for the current hour; not the 10 minute average as labelled in the dialog. Why? I don't know, it should be changed to $span($time_delta=600).windSpeed.avg.raw. I will submit a PR to the SteelSeries Weather Gauges. As for the reason why you are seeing a ridiculous wind speed, it is most likely because the gauge-data.txt file has a null (weeWX None) value for the wspeed field. When the error condition is showing up have a look at your gauge-data.txt file and see what value is against wspeed. If it is null then it is likely $hour.windSpeed.avg.raw is returning None for some reason. Why would mean looking at your underlying windSpeed data for the last hour, it may be there is no data and hence None is returned and converted to null. Gary On Monday, 20 February 2017 02:22:02 UTC+10, Robert Mantel wrote: > > I'm wondering if weewx calculates the average windspeed over 10 minutes. > My station only gives a 2 minute average and I noticed in my SteelSeries > gauges, the windspeed gauge when you hover to see historical information it > shows the windspeed avg (10 min): -35999 km/h or something to that effect. > Does weewx have a calculation for the 10 average? Not the wind gust but > the wind speed. > -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
