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ČHMÚ/CHMI – Meteorological Data Processing

Copyright (C) 2025 Mikuláš Kadečka – [email protected]

This QGIS plugin processes meteorological measurements published by the Czech Hydrometeorological Institute using spatial interpolation methods. To function properly, the tool requires all measurements to be downloaded and formatted correctly.

You can either download preprocessed datasets from this webpage or use scripts from this GitHub repository to automate the download of raw data from the CHMI website and convert them into a format suitable for GIS processing.

Note

If you are planning on using the plugin in QGIS, please download it from the official plugin repository.

What Results to Expect

Important

Please take the tool's results with caution, as this is my first attempt at creating a plugin, and the results may be distorted.

The plugin analyzes the activity of CHMI measuring stations and, based on the user-specified time interval, groups them into units with the same active periods. These groups serve as input for multiple iterations of spatial interpolation, accounting for the fact that stations frequently change locations and often switch between active and inactive states.

After generating interpolation result rasters, the tool calculates a weighted average, where the weights represent the number of active measuring days for each station group. This method can produce more accurate results compared to a single iteration of spatial interpolation.

The tool can generate the following outputs:

  • A weighted average raster (mandatory result)
  • Point layers of stations with the same active period (optional, can be enabled in the plugin’s input parameters)

How to Use the Plugin

  1. Install the plugin and either use the scripts to download and preprocess data files from the CHMI webpage or download the preprocessed dataset and extract the root folder.
  2. Start the plugin, go to the Settings tab, and set the directory path for the "spatial_data" folder obtained in the first step.
  3. Switch to the Raster tab and fill in the primary and secondary parameters.
  4. Click the Start button to run the plugin.

Tip

Be cautious when setting the extent layer parameter, which must be a vector layer - preferably a polygon - and the cell size, whose unit is determined by the chosen projection. If you want to save the plugin's output, enter a path that ends with a GIS raster file extension.

How the Plugin Works

The structure of this plugin was initially created using the Plugin Builder, but some components require further explanation. These components include:

  • i18n – A directory that stores translation files for the plugin, created using Qt Linguist.
  • functions – A Python library that contains most of the custom functions developed for this project.
  • data_chmu_dialog_base.ui – A file that defines the plugin’s user interface, created with Qt Designer.
  • data_chmu.py – A Python file partially generated by Plugin Builder. It adds functionality to the UI and processes input parameters for the core of the plugin.
  • tool.py – The core file of the plugin. It utilizes custom functions and tools from QGIS libraries, including GDAL and Processing.

If you're interested in learning more about the plugin’s functionality, please check out my bachelor's thesis.