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

[Martin Schmidt <martin.schmidt@xxxxxxxxxxxxxxxxx>]

Hi,
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