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Example Workflow

The repository includes a concrete end-to-end example in projects/example/run.sh. It demonstrates how to move from a raw IASI Level-1C granule to derived perturbation products and quick-look figures.

Steps

1. Configure the runtime environment

The script points to the local executables in src/, exports the CODA definitions, and adds locally built libraries to LD_LIBRARY_PATH.

2. Download a sample granule

If the test input file is missing, the script enters tests/data/ and runs download.sh to fetch and unpack a sample IASI Level-1C NAT file.

3. Extract a spectrum

spec2tab is used to write one selected footprint to spec.tab.

Example:

./spec2tab - "$f" i 0 30 spec.tab

The resulting table contains time, geolocation, wavenumber, brightness temperature, and radiance.

4. Compute perturbation products

perturbation reads the granule and writes a NetCDF file named pert.nc containing brightness temperature and perturbation products for the configured spectral regions.

Example:

./perturbation - pert.nc "$f"

5. Produce map tables

map_pert extracts geolocated text tables from pert.nc for:

  • 4mu
  • 15mu_high
  • 15mu_low

These tables are convenient for plotting, filtering, or downstream analysis.

6. Generate figures

The example uses gnuplot to create:

  • a spectral plot from spec.tab
  • geolocated brightness temperature maps
  • variance maps
  • perturbation maps

Running the example

From the repository root:

cd src
make
cd ../projects/example
./run.sh

Expected outputs

The example workflow produces:

  • spec.tab
  • pert.nc
  • map_4mu.tab
  • map_15mu_low.tab
  • map_15mu_high.tab
  • multiple PNG figures in projects/example/

Notes

  • gnuplot is required for the plotting step.
  • The plotting commands reference an external coastline file at ~/wrk/coast/wcl.tab.
  • Generated .tab, .nc, and image files in projects/example/ are working artifacts, not source files.