Enabling Smart Dynamical Downscaling of Extreme Precipitation Events
with Machine Learning
Xiaoming Shi

Division of Environment & Sustainability, Hong Kong University of Science and Technology, Division of Environment & Sustainability, Hong Kong University of Science and Technology, Division of Environment & Sustainability, Hong Kong University of Science and Technology
Corresponding Author:shixm@ust.hk
Author ProfileAbstract
The projection of extreme convective precipitation by global climate
models (GCM) exhibits significant uncertainty due to the coarse
resolution of GCMs, which cannot resolve fine-scale processes. Direct
dynamical downscaling (DDD) of regional climate at convection-permitting
resolutions (~1 km) provides valuable insight into the
potential changes in extreme precipitation, but its computational
expense is formidable. Here we document the effectiveness of machine
learning in enabling smart dynamical downscaling (SDD), which performs
downscaling only for a small subset of GCM data. Trained with reanalysis
and satellite data for three Asian cities, support vector machines can
filter out approximately 87% to 94% of circulation data, which are
irrelevant to extremes. Deep convolutional neural networks, trained with
larger data sets, can filter out more than 97% of circulation data and
in the selected subset, retrieve 72% to 81% of the circulation
patterns responsible for extreme events (rain intensity higher than the
99th percentile).