Wind speed

[opticsman0127]

I am not sure how, or even if, I should be calibrating/offsetting the wind speed and gusts. The default setting is 1.0 on both options. To the north of me and to the south are 2 met office stations, not exactly close but not too far, especially the southern one. From the Met office web site it is relatively simple to look at the wind speed and sometimes gusts from both stations over a 6 hour period.

The first question is:

Should I average these 2 sets of figures and then set my actual records to suit or, should I just leave the default at 1.0. If I leave it at 1.0, what is the point of having it at all?

The second question is:

Last night I adopted the action of working out an average of the 2 stations and applied an increase on the offset default to achive similar values to this average. However, when I downloaded from the data logger this morning, just after 8:00, there was a big apparent drop in wind speed/gusts. See it plainly here http://www.barrypemb.f2s.com/trends.htm

How should I be setting this somewhat arbitrary offset figures?

Barry

[steve]

It's very hard to work out what calibration value to apply for wind. My suggestion is this: just use the calibration figures to compensate for the difference in height between your anemometer and the recommended 10 metre height. Don't try to get your figures to match nearby stations, because you can never be sure that what you're doing really does apply to your location.

However, when I downloaded from the data logger this morning, just after 8:00, there was a big apparent drop in wind speed/gusts. See it plainly here http://www.barrypemb.f2s.com/trends.htm

That's odd, it looks like it's not applying the same calibration values to the logger data as it does during 'live' running. Do you have the gust multiplier and wind multiplier set to the same value? I use 1.10 for both, and I don't see the same as you on my graphs. It could well be a bug, but maybe I don't see it because I have different settings in Cumulus. I guess the main one that might affect it is the 'calculate 10-minute average' setting, which I don't have set, because the VP2 does that anyway. I'll have a look at the code.

[opticsman0127]

Odd indeed.

Not sure if I have the 2 values agreeing as I am at work at the moment. Will have a look this afternoon.

Barry

[steve]

I've noticed you're using 1.8.7; it's possible that it was a bug that I fixed in 1.8.8. Except that I haven't noted it in the change log, which I would normally do. I've looked at the current code, and it does seem to be doing the right thing, and it does seem to work OK for me.

[opticsman0127]

Do you mean there is a more up to date build since I downloaded Cumulus on Tuesday?

On a side issue, what software do you recommend to upload jpg images to web site. I have an old Philips Toucam Pro web cam.

Barry

[steve]

Do you mean there is a more up to date build since I downloaded Cumulus on Tuesday?

There are the 1.8.8 'beta' builds - see the scrolling banner near the top of the screen, and the 'Announcements and News' section of the forum.

On a side issue, what software do you recommend to upload jpg images to web site. I have an old Philips Toucam Pro web cam.

Don't know much about that, I'm afraid. I know that there are a few reasonable free bits of webcam software available that some people here use.