WW3 Downloader & Processor

Allows you to download NetCDF files from the WW3 model (Ifremer), prepare them for GRIB2 conversion compatible with QtVlm, and concatenate them.

Prerequisites

• Python 3.8+
• requests
• xarray
• tqdm
• cdo (for NetCDF → GRIB2 conversion)

Install Python dependencies:

pip install requests xarray tqdm

Install CDO (on Ubuntu/Debian):

sudo apt-get install cdo

Usage

1. Download NetCDF files

You can download the files via HTTPS (default) or FTP (using the --ftp option).

a) Download via HTTPS

python dl_files.py --zone MANCHE-NORD-500M --days_fwd 2 --download_dir ww3_data

b) Download via FTP

Prepare a credentials file (e.g. ftp_credentials.json):

{
  "user": "ext-marc_vagues",
  "password": "YOUR_PASSWORD_HERE"
}

Then run the command:

python dl_files.py --zone MANCHE-NORD-500M --days_fwd 2 --download_dir ww3_data --ftp --credentials ftp_credentials.json

• --zone: name of the zone (e.g., MANCHE-NORD-500M, FINIS-200M)
• --days_fwd: number of days to download starting from the start date
• --ftp: enables FTP download
• --credentials: path to the JSON file containing FTP credentials
• --download_dir: destination folder

2. Preprocess and concatenate the files

python process_files.py ww3_data/*.nc --output manchesud.nc --processed_dir processed_nc

• --output : name of the concatenated NetCDF file
• --processed_dir : folder for the processed NetCDF files

3. Convert to QtVlm-compatible GRIB2

Use the following command:

cdo -f grb2 copy manchesud.nc manchesud.grb2