Time zones

[Patrick Larson]

At the recent Eastern Ontario WISKI HUB Admin meeting, there was mention of time zones and EDT/EST. Somebody said something about using GMT - or + 5  in SODA. Does the Etc/GMT-5 setting not work?

[SteveWKISTERS]

Hi Pat,

I believe (and please feel free to correct me @cvance  & @Dave Eastcott) this was an issue within WISKI time series that folks had used SODA and KiDAT to correct.

In earlier versions it wasn't as simple to activate DST on WISKI timeseries, so the time stamp had to be adjusted, either through transformations in WISKI (i.e. telling the data in WISKI to move back an hour) or through the import process (SODA and KiDAT). This why some KiDAT and SODA operations had changes to their timezone configs - to account for the shift before it entered WISKI. These will need to be revised once we update the timeseries properties.

Steve with Kisters

[Patrick Larson]

More problems with SODA and time zones.

- There are two places to enter the timezone in SODA, in the poll plan on the General page and on the setup for each of the stations (right click on station name, click on Edit logger). I entered Etc/GMT-5 in both.

- I run 2 poll plans, one twice a day at 06:10 and 13:10 and the second every two hours during high flow periods from 08:10 to 22:10  to keep our public graphs near real time.

- This morning I found that the data was only up to 23:00 last night. I found however, after downloading data "manually" for a couple of stations, that SODA was getting the data but adjusting the time. Curiously, it wasn't adjusting by 10 hours, but, rather 7 or 9 or 10.

I have changed the time zone in the two poll plans to Canada/Eastern but left the station setup at Etc/GMT-5 until the next download at 12:10.

[cmcguire]

Hey Pat,

This was really confusing us as well.  Brandon pointed out that Etc/GMT is not the same as UTC or GMT and that SODA uses Etc/GMT because it runs Linux.  The Etc/GMT reverses the sign
Here's a more in depth explanation if you're too awake this morning: https://opensource.apple.com/source/system_cmds/system_cmds-230/zic.tproj/datfiles/etcetera

We use POSIX-style signs in the Zone names and the output abbreviations, even though this is the opposite of what many people expect. POSIX has positive signs west of Greenwich, but many people expect positive signs east of Greenwich. For example, TZ='Etc/GMT+4' uses the abbreviation "GMT+5" and corresponds to 5 hours behind UTC (i.e. west of Greenwich) even though many people would expect it to mean 5 hours ahead of UTC (i.e. east of Greenwich).

@cvance Do you think we'll be able to get the WISKI computers to ignore DST?  If not would going into Extras->Options->Time Zone and changing it to Fixed GMT offset: Etc/GMT+5 be a good temporary fix?
@Dave Eastcott

[Patrick Larson]

Chris:
Thanks for the response.

I don't recall why but I did switch to Etc./GMT+5 awhile ago and, as far as I can tell, it has worked. There are still some issues with Parks Canada gauges because some of the stations are on DST. But that is another matter.

[cvance]

@cvance Do you think we'll be able to get the WISKI computers to ignore DST?  If not would going into Extras->Options->Time Zone and changing it to Fixed GMT offset: Etc/GMT+5 be a good temporary fix?

Hi Chris,

Currently looking into rolling this out but I would like to get all the facts straight before doing so.  I will keep you posted.

Thanks,
Curtis

[DMcNiece]

Mentioned this on another thread... Last year Brandon from Kisters support ran a script to change all time zones in our dbase to (UTC-05:00) Generic time zone.  This avoids the whole daylight issues so we just post a disclaimer on our data that it is not corrected for daylight savings.