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Re: [ferret_users] question about @DDC with different calendar



Hi,

It uses the calendar that is defined for that grid, so internally, for all computations involving time, the time coordinates are converted to seconds since the time origin defined for that calendar.  Depending on the timesteps this will affect results of computations like averages and integrals and derivatives.  If the timestep is days, then of course the number of seconds in a day doesn't vary - but if the timesteps are longer, for instance months or years you would see a difference.

-Ansley

On 1/16/2020 11:23 AM, Xiaoyu Bai wrote:
Dear ferreters,

I am applying L=@DDC to some model outputs in a loop (repeat). According to the general info of @DDC (https://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/variables-xpressions/XPRESSIONS#GeneralInfo), "Ferret attempts to use standardized units for the grid coordinates, ..., If the underlying axis is in a known unit of time Ferret converts grid box lengths to seconds". My question here is does "ferret convert grid to standardized time unit" mean ferret convert time to Gregorian calendar seconds. Or ferret convert seconds according to the calendar itself. I also have 360_DAY and NOLEAP calendar from my model output.

Cheers,    

--
Xiaoyu

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