Generative climate downscaling enables high-resolution compound risk assessment by preserving multivariate dependencies

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Hauptverfasser: Kutsuna, Takuro, Ishizaki, Noriko N., Oyama, Norihiro, Yoshida, Hiroaki
Format: Preprint
Veröffentlicht: 2026
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author Kutsuna, Takuro
Ishizaki, Noriko N.
Oyama, Norihiro
Yoshida, Hiroaki
author_facet Kutsuna, Takuro
Ishizaki, Noriko N.
Oyama, Norihiro
Yoshida, Hiroaki
contents Physics-based climate projections using general circulation models are essential for assessing future risks, but their coarse resolution limits regional decision-making. Statistical downscaling can efficiently add detail, yet many methods treat variables independently, degrading inter-variable relationships that govern compound hazards such as heat stress, drought, and wildfire. Here we show that a diffusion-based multivariate generative framework, combined with bias correction, recovers degraded inter-variable correlations even under a 50$\times$ increase in linear resolution. When applied to five meteorological variables over Japan, the framework reduces inter-variable correlation errors by more than fourfold relative to existing baselines while improving both univariate and spatial accuracy, leading to more accurate detection of severe drought. These results demonstrate that multivariate generative downscaling improves the reliability of compound risk assessment under large resolution gaps.
format Preprint
id arxiv_https___arxiv_org_abs_2605_11531
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Generative climate downscaling enables high-resolution compound risk assessment by preserving multivariate dependencies
Kutsuna, Takuro
Ishizaki, Noriko N.
Oyama, Norihiro
Yoshida, Hiroaki
Atmospheric and Oceanic Physics
Machine Learning
Applications
Physics-based climate projections using general circulation models are essential for assessing future risks, but their coarse resolution limits regional decision-making. Statistical downscaling can efficiently add detail, yet many methods treat variables independently, degrading inter-variable relationships that govern compound hazards such as heat stress, drought, and wildfire. Here we show that a diffusion-based multivariate generative framework, combined with bias correction, recovers degraded inter-variable correlations even under a 50$\times$ increase in linear resolution. When applied to five meteorological variables over Japan, the framework reduces inter-variable correlation errors by more than fourfold relative to existing baselines while improving both univariate and spatial accuracy, leading to more accurate detection of severe drought. These results demonstrate that multivariate generative downscaling improves the reliability of compound risk assessment under large resolution gaps.
title Generative climate downscaling enables high-resolution compound risk assessment by preserving multivariate dependencies
topic Atmospheric and Oceanic Physics
Machine Learning
Applications
url https://arxiv.org/abs/2605.11531