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[netCDF #CWC-499413]: FW: Need assistance - USCG-SAR netCDF particle files

Hello,

The command-line tools used for working with netCDF files, packaged with 
libnetcdf, do not provide an easy way to combine/merge individual files.  To do 
what you're suggesting, a post-processing script using the netcdf4-python 
package (available from https://github.com/Unidata/netcdf4-python), written in 
python, might be best.  This approach would require opening the individual 
files in question, aggregating the data from individual files, and either 
appending to a third file (as you suggest, along an UNLIMITED dimension), or 
writing out to a newly created file.  You might also look at the NetCDF 
Operators (NCO) tools, available here: http://nco.sourceforge.net, as they may 
offer functionality that will do what you're looking for.  The NCO package, 
maintained externally, provides more complex functionality than the ncdump, 
nccopy and ncgen tools Unidata provides.  

I'm sorry I can't provide an off-the-shelf solution that Unidata maintains, but 
hopefully this will get you started in the right direction! 

Have a good afternoon,

-Ward

> 
> From: Forbes, Cristina CIV
> Sent: Tuesday, June 29, 2021 1:33 PM
> To: address@hidden
> Subject: Need assistance - USCG-SAR netCDF particle files
> 
> 
> Good morning UCAR NetCDF team:
> 
> I am the oceanographer for the USCG Office of Search and Rescue (CG-SAR). I 
> am wondering if you can assist us with netCDF files.
> 
> As a background CG-SAR uses the Search and Rescue Optimal Planning System 
> (SAROPS) to perform drift modeling for search and rescue and planning 
> missions for persons and crafts lost at sea.  SAROPS accesses the 
> Environmental Data Server (EDS) to retrieve surface currents and winds from 
> various government and academic sources to perform the drift modeling. SAROPS 
> uses a Monte Carlo approach to drift thousands of particles and then generate 
> probability maps to determine the best search areas where to deploy the USCG 
> Search and Rescue units (SRUs: helicopters, airplanes, vessels).
> 
> At the moment we use only one surface current product and one wind product to 
> perform the drift simulations. We are trying to explore the possibility of 
> creating ensembles (e.g. simulations with several pairs of current/winds) to 
> produce our probability maps that would provide a greater probability of 
> success.
> 
> To that effect, we would like to be able to start by merging/combining 2 
> particle.nc files (that were generated from running 2 simulations) into one, 
> so then we can generate the probability maps. However we are having problems 
> with the netCDF files - as far as we can tell, they are not standard.
> 
> Attached find an example of 2 particle netCDF files (A_particles.nc and 
> B_particles.nc) that we would like to be able to merge and then see how the 
> merged file would fit into the entire SAROPS system. The particle variable is 
> the one that we would want to expand (UNLIMITED dimension? like time in 
> numerical models?) adding the information of the 2500 particles in file A and 
> the 2500 particles in file B.
> 
> Could you or someone in your team assist us in producing the combined A and B 
> particle file so we can assess if ensembles could successfully benefit our 
> search and rescue missions?
> 
> Thank you!
> Cristina
> 
> ------------------------------------------------
> Dr. Cristina Forbes
> Oceanographer
> U.S. Coast Guard Headquarters
> Office of Search and Rescue (CG-SAR)
> 2703 Martin Luther King Jr. Ave SE
> Washington, D.C. 20593-7363
> +1 202- 372-2231 (phone)
> +1 202-374-2727 (mobile)
> +1 202-372-2912 (fax)
> address@hidden<mailto:address@hidden>
> ------------------------------------------------
> 


Ticket Details
===================
Ticket ID: CWC-499413
Department: Support netCDF
Priority: Normal
Status: Closed
===================
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