Developing an Explainable Variational Autoencoder (VAE) Framework for
Accurate Representation of Local Circulation in Taiwan
Abstract
This study develops an explainable variational autoencoder (VAE)
framework to efficiently generate high-fidelity local circulation
patterns in Taiwan, ensuring an accurate representation of the physical
relationship between generated local circulation and upstream synoptic
flow regimes. Large ensemble semi-realistic simulations were conducted
using a high-resolution (2 km) model, TaiwanVVM, where critical
characteristics of various synoptic flow regimes were carefully selected
to focus on the effects of local circulation variations. The VAE was
constructed to capture essential representations of local circulation
scenarios associated with the lee vortices by training on the ensemble
dataset. The VAE’s latent space effectively captures the synoptic flow
regimes as controlling factors, aligning with the physical understanding
of Taiwan’s local circulation dynamics. The critical transition of flow
regimes under the influence of southeasterly synoptic flow regimes is
also well represented in the VAE’s latent space.This indicates that the
VAE can learn the nonlinear characteristics of the multiscale
interactions involving the lee vortex. The latent space within VAE can
serve as a reduced-order model for predicting local circulation using
synoptic wind speed and direction. This explainable VAE ensures the
accurate predictions of the nonlinear characteristics of multiscale
interactions between synoptic flows and the local circulation induced by
topography, thereby accelerating the assessments under various climate
change scenarios.