Author Topic: Archive data timestamping on DST start and end days  (Read 613 times)

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Offline OlyWater

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Archive data timestamping on DST start and end days
« on: November 08, 2022, 01:40:06 PM »
WIth the end of daylight savings time last weekend, I noted that the daily rainfall total displayed on my Vantage Pro 2 console was reading 0.99inch at midnight. This is also the total reported in the CWOP time series table online. However, the daily total shown in the Weatherlink 6.0.5 CF6 report is 0.97. Looking at the timestamping on the CWOP time series and on the Weatherlink data browser, the discrepancy appears to result from the additional hour's worth of accumulation over a 25 hour day due to the end of DST. That is to say, the CWOP time series shows two intervals of data with timestamps between 1:00am and 2:00am. The first interval is on DST, the second interval is on standard tme after the local clocks fall back.

The WL data browser doesn't do this. Its timestamps roll from the 1:00am - 2:00am interval into the 2:00am-3:00am interval, so that it reflects a 24-hour day. This raises the question for me of whether the WL data is stored in the archive by UTC, and whether its CF6 or other daily summary products need to adjusted for a time offset during DST.

I presume a similar desynchronization issue between the rain total on the console display and the WL CF6 report could also arise at the beginning of DST due to that being a 23 hour day.

Does anyone in the community have any deeper knowledge about WL archive data timestamping?