NCCUTOUT

Basic Information

Name of Program

NCCUTOUT

Version-Date

November 2018

Description-Date

November 2018

Catchwords

data analysis
postprocessor
cut out data
synoptic data sets
tidal characteristic numbers
tide-independent characteristic numbers
differences of data sets
CF NetCDF format for 2D/3D data
support of computational results based on sub-grid bathymetry
support of DMQS metadata and variables

Acknowledgment: This project took advantage of netCDF software developed by UCAR/Unidata (www.unidata.ucar.edu/software/netcdf/).

Short Description of Functionality

The postprocessor NCCUTOUT may help users to reduce the size of result files in order to save disk space and time in the subsequent processing steps. It cuts out data of UGRID compliant NetCDF files of the area type. In UGRID metadata language the files have to have at least one mesh topology variable with the attribute topology_dimension = 2.

The cutting is typically defined by one polygon. The elements inside of the polygon get extracted to the result file. The user can select with a positive or negative list, which geophysical variables should be extracted.

But the cut out area can also be defined by two or more polygons which need not be direct neighbours. Though the results may look like seperate spots they share a common mesh topology.

File:NCCUTOUT patch.png

Picture control volumes and exchanges.

Input-Files

1. general input data (file type nccutout.dat);
2. input UGRID CF NetCDFs (file type cf-netcdf.nc);
3. cutout polygons (file type ipds.dat);
4. xxx for automatic quality assurance (file type bounds_verify.dat).

Output-Files

1. output UGRID CF NetCDFs (file type cf-netcdf.nc);
2. (optional) informative printer file of program execution (file type nccutout.sdr)
3. (optional) trace of program execution (file type nccutout.trc)

Methodology

NCCUTOUT can process NetCDF files supporting the UGRID idea of parent and child meshes, e.g. a computational grid with a coarse and a sub grid with higher resolution. Whether data gets cut out or not depends from the position of the geometric elements in the coarsest mesh. This is displayed in Fig. 1. Certain faces of the coarser computational grid are cut out and subsequently all subfaces inside these coarser faces are extracted. This methods leads to consistent meshes and parent child connections.

It is recommended to use NCCUTOUT for reducing the size of the output of the numerical engines, e.g. UNTRIM2007 and UnTRIM2, so that the complete postprocessing benefits from the reduction.

An introduction how to collect DMQS metadata can be found here.

Performance: Most of the program's CPU time is used by basic IO routines. Since output is considerably slower than input a reduction of the output data, area and geophysical variables, makes NCCUTOUT run faster.

Program(s) to run before this Program

NCANALYSE, NCCHUNKIE, NCDELTA, INSEL2IPDS, UNTRIM2007, UNTRIM2

Program(s) to run after this Program

DAVIT, NCAGGREGATE, NCANALYSE, NCAUTO, NCCHUNKIE, NCDELTA, NCPLOT, NC2TABLE and MATLAB

Additional Information

Language

Fortran95

Additional software

---

Original Version

P. Schade, G. Lang

Maintenance

P. Schade, G. Lang

Documentation/Literature

• Template Files:
  • template files available in $PROGHOME/examples/nccutout

---

back to Program Descriptions

---

Overview