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arXiv · 2507.01354

Efficient Kilometer-Scale Precipitation Downscaling with Conditional Wavelet Diffusion

Chugang Yi·Minghan Yu·Weikang Qian·Yixin Wen·Haizhao Yang
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Abstract

Effective hydrological modeling and extreme weather analysis demand precipitation data at a kilometer-scale resolution, which is significantly finer than the 10 km scale offered by standard global products like IMERG. To address this, we propose the Wavelet Diffusion Model (WDM), a generative framework that achieves 10x spatial super-resolution (downscaling to 1 km) and delivers a 9x inference speedup over pixel-based diffusion models. WDM is a conditional diffusion model that learns the learns the complex structure of precipitation from MRMS radar data directly in the wavelet domain. By focusing on high-frequency wavelet coefficients, it generates exceptionally realistic and detailed 1-km precipitation fields. This wavelet-based approach produces visually superior results with fewer artifacts than pixel-space models, and delivers a significant gains in sampling efficiency. Our results demonstrate that WDM provides a robust solution to the dual challenges of accuracy and speed in geoscience super-resolution, paving the way for more reliable hydrological forecasts.

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Chugang Yi, Minghan Yu, Weikang Qian, Yixin Wen, Haizhao Yang. 2025-07-02. Efficient Kilometer-Scale Precipitation Downscaling with Conditional Wavelet Diffusion. https://doi.org/10.1029/2025jh000941

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