Target Parameterization in Diffusion Models for Nonlinear Spatiotemporal System Identification

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Main Authors: Messaoudi, Achraf El, Khaous, Noureddine, Cherifi, Karim
Format: Preprint
Published: 2026
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author Messaoudi, Achraf El
Khaous, Noureddine
Cherifi, Karim
author_facet Messaoudi, Achraf El
Khaous, Noureddine
Cherifi, Karim
contents Machine learning is becoming increasingly important for nonlinear system identification, including dynamical systems with spatially distributed outputs. However, classical identification and forecasting approaches become markedly less reliable in turbulent-flow regimes, where the dynamics are high-dimensional, strongly nonlinear, and highly sensitive to compounding rollout errors. Diffusion-based models have recently shown improved robustness in this setting and offer probabilistic inference capabilities, but many current implementations inherit target parameterizations from image generation, most commonly noise or velocity prediction. In this work, we revisit this design choice in the context of nonlinear spatiotemporal system identification. We consider a simple, self-contained patch-based transformer that operates directly on physical fields and use turbulent flow simulation as a representative testbed. Our results show that clean-state prediction consistently improves rollout stability and reduces long-horizon error relative to velocity- and noise-based objectives, with the advantage becoming more pronounced as the per-token dimensionality increases. These findings identify target parameterization as a key modeling choice in diffusion-based identification of nonlinear systems with spatial outputs in turbulent regimes.
format Preprint
id arxiv_https___arxiv_org_abs_2604_17566
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Target Parameterization in Diffusion Models for Nonlinear Spatiotemporal System Identification
Messaoudi, Achraf El
Khaous, Noureddine
Cherifi, Karim
Systems and Control
Machine Learning
Fluid Dynamics
Machine learning is becoming increasingly important for nonlinear system identification, including dynamical systems with spatially distributed outputs. However, classical identification and forecasting approaches become markedly less reliable in turbulent-flow regimes, where the dynamics are high-dimensional, strongly nonlinear, and highly sensitive to compounding rollout errors. Diffusion-based models have recently shown improved robustness in this setting and offer probabilistic inference capabilities, but many current implementations inherit target parameterizations from image generation, most commonly noise or velocity prediction. In this work, we revisit this design choice in the context of nonlinear spatiotemporal system identification. We consider a simple, self-contained patch-based transformer that operates directly on physical fields and use turbulent flow simulation as a representative testbed. Our results show that clean-state prediction consistently improves rollout stability and reduces long-horizon error relative to velocity- and noise-based objectives, with the advantage becoming more pronounced as the per-token dimensionality increases. These findings identify target parameterization as a key modeling choice in diffusion-based identification of nonlinear systems with spatial outputs in turbulent regimes.
title Target Parameterization in Diffusion Models for Nonlinear Spatiotemporal System Identification
topic Systems and Control
Machine Learning
Fluid Dynamics
url https://arxiv.org/abs/2604.17566