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[ferret_users] [ferret_users] time axis regridding - noninteger @ngd

I am trying to arrange station data into a time series. Each station file has full 4d coordinates, horizontal and vertical coordinates are the same, the time axis in the station files has one time step each.

Concatinating works by opening file after file (in the right order) and saving to the final file like this

save/append/file=station.nc oxygen

The data are distributed very irregularly, 2-6 data sets within 2-3 days and nothing inbetween for weeks.

Now I want to put the data onto a regular, say a daily time axis. For the days where I have data I want to get the average over all data belonging to the special day and a missing value otherwise.

use station.nc
define axis/t=1-jan-2014:31-aug-2015:1/t0=1-jan-2000/unit=days tnew

let ox_day = oxygen[gt=tnew@ave]

However, this gives constant values for the days but the same within the gaps. A "shade" looks like displaying the original data "oxygen" with shade.

Using the @min or @max transformation gives non-missing values only for the days, where station data are available. This is the desired behaviour.

@sum and @ngd transformation gives nozero values for each day, very small but finite for days without station data and of almost correct size for days with station data. @ngd is not integer - a little bit below the expected value for days with station data and almost zero but finite within gaps.

I tried to use the bounds-qualifier. When concatinating the files I get an error message, but after concatination I can resave the data with the bounds qualifier as described in the manual. This does not change the bahaviour.

So my question: what I am doing wrong or is this a bug? How do I get integer @ngd values - especially exactly zero for days without data?

Many thanks,
Martin Schmidt

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