Preprints
https://doi.org/10.5194/egusphere-2025-4831
https://doi.org/10.5194/egusphere-2025-4831
07 Oct 2025
 | 07 Oct 2025
Status: this preprint is open for discussion and under review for Weather and Climate Dynamics (WCD).

A Promising Downscaling Strategy for Topographic Heavy Rainfalls over the Asian-Australian Monsoon Region by Leveraging Multi-Scale Moisture Dynamical Control

Jia-Xin Guo, Wei-Ting Chen, and Chien-Ming Wu

Abstract. Conventional downscaling methods are severely challenged in providing future projections for local precipitation extremes over tropical areas with complex terrain. Here, we investigate the multi-scale moisture dynamical control on the topographic heavy rainfalls over Taiwan to construct an alternative downscaling pathway based on crucial physical processes. We identify large-scale regimes of vertically-integrated vapor transport (IVT) with objective machine learning classification and then quantify embedded upstream IVT conditions that drive distinct local rainfall responses over Taiwan, which are verified by semi-realistic large-eddy simulations with realistic topography. The identified environmental control and the resolved convective processes form the physical basis for providing interpretable and high-resolution rainfall projections in a changing climate. In addition to Taiwan, the applicability of this downscaling strategy to four areas in the Asian-Australian monsoon region exhibiting high sensitivity of heavy topographic rainfall to the upstream moisture dynamics is also discussed.

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Jia-Xin Guo, Wei-Ting Chen, and Chien-Ming Wu

Status: open (until 18 Nov 2025)

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Jia-Xin Guo, Wei-Ting Chen, and Chien-Ming Wu

Data sets

Large Data Files for "A Promising Downscaling Strategy for Topographic Heavy Rainfalls over the Asian-Australian Monsoon Region by Leveraging Multi-Scale Moisture Dynamical Control" Jia-Xin Guo https://doi.org/10.5281/zenodo.17199183

Model code and software

Model Code for "A Promising Downscaling Strategy for Topographic Heavy Rainfalls over the Asian-Australian Monsoon Region by Leveraging Multi-Scale Moisture Dynamical Control" Jia-Xin Guo https://doi.org/10.5281/zenodo.17230674

Jia-Xin Guo, Wei-Ting Chen, and Chien-Ming Wu
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Latest update: 07 Oct 2025
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Short summary
This study unravels the large-scale and upstream moisture dynamical control on distinct heavy rainfall behaviours over Taiwan's complex terrain. With machine-learning-based large-scale dynamical regimes that preserve the multi-scale circulation features of the Asian-Australian monsoon, and large-eddy simulations with realistic topography that realize local rainfall outcomes, this work provides a process-based alternative pathway to project topographic heavy rainfalls in the future climate.
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