Wind speed too high on re-starting Cumulus

[Ben]

I shut down my computer every 2 - 4 weeks for maintenance. I have noticed on re-starting Cumulus, I get an unusually high wind speed result. My wind speed is calculated by Cumulus; and I do have a multiplier of >1 being almost completely surrounded by trees. All other extremes are normal, including wind gust, which is also multiplied.
Is it possible Cumulus is accumulating wind speed instead of replacing the value as it downloads from the logger?
Ben

[steve]

It's because there isn't enough data to do a proper 10-minute average, so the result ends up being very close to the 'current' 3-second reading.

I'm assuming in saying this that you're not getting ridiculously high values?

[Ben]

At times, the high gust may be recorded as about 20 km/h, while the high speed may be 50 km/h. Doing the maintenance on the computer may take anywhere from 10 minutes to an hour, depending on what needs to be done.
Ben.

[steve]

I need specific examples. If you zip up the diags folder and attach it, along with your monthly log file, I'll take a look, but I'll need to know exactly what and when I'm looking for.

[Ben]

mar26winddata.jpg

The blue line is the average wind speed. You can see that the wind speed is initially being calculated correctly during the first 4 or 6 values on the graph, and then I restart Cumulus. The wind speed rockets up to above the gust values, and then corrects itself as times go on. The data is saved in 5 minute intervals. This is the only example I have left; I normally adjust the data to show a more likely wind speed. This is an excerpt from last month; I haven't yet labelled the graph but it should be enough to demonstrate what I mean.
Ben

Edited after studying figures.... I believe you were right on your first post, when you said it had to do with there being insufficient data to generate a correct first number; it appears Cumulus calculates the first average after re-starting as being equal to the first gust value. As I use a multiplier of 2.5 for wind gust, and a multiplier of 3.0 for wind speed, I find that the calculated average is 3/2.5 times the wind gust.

And yes, I do know that hacking speeds like that is terrible practice, but being where I am it's the best I can do. Surprisingly, my adjusted wind speeds and averages do come fairly close to what I can find around me to compare.

Thank you very much for your time, I'm sorry to have troubled you.

Ben.

[steve]

it appears Cumulus calculates the first average after re-starting as being equal to the first gust value.

It uses all of the data available to it, i.e. all of the wind speed readings for the last 10 minutes.

Because of a bug in the Davis DLL where it never supplies the latest logger entry, there is one less reading available at the switch over from logger data to live data, typically only one entry, so the 10-minute average is inflated at that point by it actually being just one 2.5-second reading; the effect is magnified by your very large multiplier.