TMA severe weather alert data extraction

Scripts and functions for extracting weather alert data from Tanzanian Meteorological Authority ``Five days Severe weather impact-based forecasts'' PDFs.

These PDFs follow a standard format, with the first page showing weather alerts for the day of issue and the second page describing alerts for the subsequent four days. For each day, colour-coded weather alert areas are drawn over a map of Tanzania, with weather type indicated by symbols comprising a collection of vector graphics and further details available in associated text.

This code seeks to extract weather alert information for the four days subsequent to the issue date and to convert this information to standardised gridded data that can be compared with observational weather data.

Requirements

The Python environment required by the code is specified in environment.yml. Create the environment using conda:

conda env create -f environment.yml

The resulting environment is activated as necessary by the scripts or it can be activated manually:

conda activate tma_data_extraction

The code uses a third-party script pdf-parser.py (available at https://blog.didierstevens.com/programs/pdf-tools/) to extract PDF contents. Ensure that this script is available by placing it in the python directory or by specifying its location in a PDF_PARSER_ROOT environment variable:

export PDF_PARSER_ROOT=path/to/pdf-parser.py

Usage

To extract weather alert information from the documents in data_dir, placing the results in output_dir, which is created if it does not already exist:

./extract_PDF_data.sh data_dir output_data_dir

The script produces netCDF files that contain separate data layers for each alert area extracted from the PDF. Each layer is assigned an alert level based on the colour of the alert area in the original PDF. Currently, the weather type is not automatically assigned and must be specified manually. Run the following script to validate the netCDF data and assign weather type information:

./check_alert_data.sh output_data_dir reviewed_data_dir

This script displays each alert area on a map of Tanzania and provides options to adjust alert level and weather type and to flag areas for review.