Let’s say in my model I have three different rivers, with three different Qbar (m3/s) and I want to add a tracer runoff in each river. Let’s name my tracer TRAC1.
Usually it’s easy to have daily river flows so qbar_time is the same for all rivers, and thus I can dimension qbar(n_qbar, qbar_time) in my runoff.nc file. (same as in the given default runoff.nc file I think)
On the contrary the concentrations of TRAC1 depend on measurements that would probably have been collected at different times so I cannot dimension my variable ccTRAC1(n_ccTRAC1, ccTRAC1_time).
How can I define my TRAC1 concentrations taken at different timesteps in different rivers ? Do I have to define a new time dimension in the runoff.nc file for each tracer AND each river ? (this may result in runoff.nc files with numerous dimensions in case of many tracers)
As far as I understand CROCO will do a linear interpolation between the two closest points available for a variable to fill the gap when there is need of an observation/record.
My recommendation woulld be for you to create an array of concentrations for the same timesteps you are defining the river flow, with linearly interpolated values. That way you will have all arrays with the same dimension.
To my point of view, you can define in the croco_runoff.nc file, various “concentrations” time, that can differ from the “flow/qbar” time associated. Indeed a linear interpolation is done for the river flow (get_psource.F + cpp key PSOURCE_NCFILE) BUT LASO for the concentrations (get_psource_ts.F + cpp key PSOURCE_NCFILE_TS)
But you are right, these “concentrations” time will be considered the same for all the rivers… So, unless I’m wrong, you can define a new time dimension in the runoff.nc file for each tracer BUT NOT for each river. This is not implemented yet.
As suggested by Andres, a solution would be to set-up an offline linear temporal interpolation for each concentration arrays you have at its highest frequency of observations, in order to keep the maximum precisions.
As a result, a given “concentration” array, cc_itrc(riv_number,cc_time), will have the same temporal dimension cc_time, for all the rivers