TC-GEN: Data-driven Tropical Cyclone Downscaling using Machine
Learning-Based High-resolution Weather Model
Abstract
Synthetic downscaling of tropical cyclones (TCs) is critically important
to estimate the long-term hazard of rare high-impact storm events.
Existing downscaling approaches rely on statistical or
statistical-deterministic models that are capable of generating large
samples of synthetic storms with characteristics similar to observed
storms. However, these models do not capture the complex two-way
interactions between a storm and its environment. In addition, these
approaches either necessitate a separate TC size model to simulate storm
size or involve post-processing to introduce asymmetries in the
simulated surface wind. In this study, we present an innovative
data-driven approach for TC synthetic downscaling. Using a machine
learning-based high-resolution global weather model (ML-GWM), our
approach is able to simulate the full life cycle of a storm with
asymmetric surface wind that accounts for the two-way interactions
between the storm and its environment. This approach consists of
multiple components: a data-driven model for generating synthetic TC
seeds, a blending method that seamlessly integrate storm seeds into the
surrounding while maintain the seed structure, and a recurrent neural
network-based model for correcting the biases in maximum wind speed.
Compared to observations and synthetic storms simulated using existing
statistical-deterministic and statistical downscaling approaches, our
method shows the ability to effectively capture many aspects of TC
statistics, including track density, landfall frequency, landfall
intensity, and outermost wind extent. Taking advantage of the
computational efficiency of ML-GWM, our approach shows substantial
potential for TC regional hazard and risk assessment.