Dayfile Mean Temp Wrong if MX not running 24H
Posted: Mon 15 Feb 2021 2:49 pm
While setting up my new website with Cumulus MX, I noticed that my NOAA heating degree days data didn't look right. For example, on February 3rd, the first full day of data I have, the recorded mean temperature for the day was 8.6, but the heating degree days recorded was only 2.3 - heating/cooling degree day base is set to 18.3, and the temperature was below this value all day (ie. no cooling degree days recorded).
I started digging into this by pulling up the Feb21log file in excel and calculating the average temperature for the day to see if something strange was going on, and to my surprise, taking the average of the recorded 5-minute data points for February 3rd gave me 3.9°C. If the number was within a few decimal points of 8.6°C I would not be concerned, but a difference of 4.7°C is too much to chalk up to variability in the 1-minute live data vs 5-minute logged data.
After taking a look at other days this month, my conclusion is that the problem appears when Cumulus is not running live for the entire 24-hour period. The biggest error I found was on the 3rd - I was still trying to get my Weatherlink live to communicate properly with cumulus at this point, and most data for that day was downloaded from Weatherlink rather than recorded live. The temperature was close to freezing for much of the day, but warmed up to about 10°C at night, which is when I got Cumulus running, and lines up with the recorded mean temp of 8.6°C being so much higher than the average of the 5-min data (the cold temperatures earlier in the day are either not being weighted the same as the data recorded live, or are being ignored).
I am not entirely sure what is causing this problem. Looking back through the backup/daily folders, most days which had folders created at 12:00 AM (ie. Cumulus was running overnight) have mean temperatures and NOAA degree days which seem correct, but days with folders that were created later in the day (for example, if Cumulus was not running overnight and was started at 9:00 AM) have mean temps which don't match up with the log files and Heating Degree Day totals that are significantly lower than other days.
I have attached my Feb21log file, dayfile, and a screenshot of backup file creation times. Please note that a few of the folders with 12:00 folder creation times did not end up having Cumulus running for 24 hours due to overnight PC updates/restart. February 7th was a day which ran without interruption which could be used for comparison. Please let me know if any other info or files are required to figure out why this is happening.
I started digging into this by pulling up the Feb21log file in excel and calculating the average temperature for the day to see if something strange was going on, and to my surprise, taking the average of the recorded 5-minute data points for February 3rd gave me 3.9°C. If the number was within a few decimal points of 8.6°C I would not be concerned, but a difference of 4.7°C is too much to chalk up to variability in the 1-minute live data vs 5-minute logged data.
After taking a look at other days this month, my conclusion is that the problem appears when Cumulus is not running live for the entire 24-hour period. The biggest error I found was on the 3rd - I was still trying to get my Weatherlink live to communicate properly with cumulus at this point, and most data for that day was downloaded from Weatherlink rather than recorded live. The temperature was close to freezing for much of the day, but warmed up to about 10°C at night, which is when I got Cumulus running, and lines up with the recorded mean temp of 8.6°C being so much higher than the average of the 5-min data (the cold temperatures earlier in the day are either not being weighted the same as the data recorded live, or are being ignored).
I am not entirely sure what is causing this problem. Looking back through the backup/daily folders, most days which had folders created at 12:00 AM (ie. Cumulus was running overnight) have mean temperatures and NOAA degree days which seem correct, but days with folders that were created later in the day (for example, if Cumulus was not running overnight and was started at 9:00 AM) have mean temps which don't match up with the log files and Heating Degree Day totals that are significantly lower than other days.
I have attached my Feb21log file, dayfile, and a screenshot of backup file creation times. Please note that a few of the folders with 12:00 folder creation times did not end up having Cumulus running for 24 hours due to overnight PC updates/restart. February 7th was a day which ran without interruption which could be used for comparison. Please let me know if any other info or files are required to figure out why this is happening.
)
Yes, I missed the chill hours and degree days. Added for the next release.