growing degree day calculation?

[finice]

hi.

i'm wondering what is the way to do calculations with cumulus.

i'm trying to discover how to calculate "growing degree day" (http://en.wikipedia.org/wiki/Growing_degree_day) with my weatherstation data collected by cumulus.

does someone have solution or good hint how to do this?

[steve]

Cumulus logs the daily average temperature in dayfile.txt. From the link you gave, the calculation is simply that figure minus a 'base' figure of 10 degrees. So if you import dayfile.txt into a spreadsheet, you can create a column to do that calculation for each day.

Cumulus supplies 'heating degree days' and 'cooling degree days' in the NOAA reports; the latter is very similar to growing degree days, but is calculated on a minute-by-minute basis, so in theory gives a 'better' figure than just taking the daily average.

[philbertp2]

Steve,

Could you check to see if you have the HDD and CDD calculations inverted? I ran the NOAA report for base 65 F and it shows no HDD days, but plenty of CDD. Fun stuff!! 66 F on the Oregon Coast Thu-Fri. HEAVEN!!!

Phil

[sfws]

(deleted)

[steve]

Could you check to see if you have the HDD and CDD calculations inverted?

The NOAA report takes the figures from dayfile.txt. If you did a 'create missing' in the dayfile.txt editor with a version before 1.9.4 build 1083, it would have got the figures the wrong way round in dayfile.txt. I'm not aware of any other problems. Your entry for 23rd Jan looks better, so presumably that was created 'live'?

[philbertp2]

Hi Steve,

Thanks for the weekend update. I am running 1.9.4 1086.

I need to do my homework on the dayfile.txt. I see there is an editor, but not sure if that is the solution.
I don't remember profiling the "Missing" button on. Is there a view feature to verify if it is turned on?

Seems that the NOAA report would dynamically generate values based on the input criteria in "Configuration."
It did a nice job when I changed my temperature and rain comparisons thresholds.
I will use the NCDC 65 F. as the HDD/CDD days threshold.

I REALLY like the report and only activated it a few days ago. That might be part of the problem.

All the best!
Phil

[steve]

I need to do my homework on the dayfile.txt. I see there is an editor, but not sure if that is the solution.
I don't remember profiling the "Missing" button on. Is there a view feature to verify if it is turned on?

It's not something you turn on and off, clicking it causes the log files to be scanned to generate any missing entries in dayfile.txt. I mentioned it as it's the only problem I'm aware of regarding the heating and cooling days.

Seems that the NOAA report would dynamically generate values based on the input criteria in "Configuration."

You need to read the help for the NOAA setup screen. The setting isn't dynamic, it controls the way that the data is gathered for storing in dayfile.txt.

I can't explain why you have a 'cooling' figure for days before the 23rd; the default for both heating and cooling is 65F, so it should have been using that anyway. If you had selected degrees C for temperature unit when you first ran Cumulus, it would have set the threshold in degrees C, which would explain it. I can't think of any other reason. I'll check the code; it's possible there's another bug somewhere.

[philbertp2]

These might be useful. They aren't big, well not yet...

[philbertp2]

Other one.

[philbertp2]

Steve,

Read the fine print on NOAA Report. No turning back. Not a problem.
I think that your formulas are working correctly. We have had some very warm weather out here, so we had some heating degrees.
Okay. Back to learning more about this complex and fun system.

Phil