Description

Stochastic weather generators (SWG) are emulators of climate/meteorological variables (like temperature or precipitation). They replace the equations of physics by a random process (usually a Markov chain with latent states) with suitable statistical and physical properties. IPSL has devised a SWG based on analogs of circulation (circulation is the latent state) to simulate temperature or precipitation. This SWG can be run in an Importance Sampling setting for hot or cold temperatures. It has been used to simulate worst cases heatwaves in Paris, or worst case cold spells in France. The main advantage of such a tool is its computing light weight, compared to running a full climate model.

Potential Users

Urban planning, adaptation to climate change.

Guide

An overview and application of the tool is provided in the paper:

Cadiou, C. and Yiou, P.: Simulating record-shattering cold winters of the beginning of the 21st century in France, Weather Clim. Dynam., 6, 1–15, https://doi.org/10.5194/wcd-6-1-2025, 2025.

Availability

Code available on github: https://doi.org/10.5281/zenodo.10726791 

Use Cases

• Paris summer heatwave before 2050 (https://doi.org/10.1038/s41612-023-00500-5)
• European extreme cold spells (https://doi.org/10.5194/wcd-5-943-2024, https://wcd.copernicus.org/articles/6/1/2025)

Reference

Cadiou, C. and Yiou, P.: Simulating record-shattering cold winters of the beginning of the 21st century in France, Weather Clim. Dynam., 6, 1–15, https://doi.org/10.5194/wcd-6-1-2025, 2025.