Generating An Ensemble of Environment-informed, Convection-permitting
Dynamical Downscaling Simulations for Climate-change Projections of
Hazardous Convective Weather
Abstract
Convection-permitting dynamical downscaling (CPDD) allows for an
explicit representation of the storm-scale generators of tornadoes,
hail, severe thunderstorm winds, and locally heavy precipitation.
Possible changes in such hazardous convective weather (HCW) due to
human-induced climate change are therefore projected with higher
confidence using CPDD than with analyses of relatively coarse global
climate models (GCM). However, the computational resources necessary for
CPDD are significant and therefore CPDD-based future projections of HCW
have tended to be based on a single experiment, and thus absent of
uncertainty measures otherwise determined with an ensemble of
experiments via an ensemble of GCMs. Herein we present
“environment-informed” CPDD as a means to efficiently generate a CPDD
ensemble driven by different GCMs. This variant of CPDD is applied only
to a subset of days and geographical domains over which the
meteorological conditions potentially favor HCW; unnecessary model
integrations on meteorologically unfavorable days and domains are
thereby eliminated. The selection procedure also accounts for GCM
biases.The temporal and geospatial occurrence of historical HCW over the
United States is demonstrated from the perspective of
environment-informed CPDD as applied to eight different GCMs and ERA5
reanalysis. The overall geographical distributions in HCW vary
considerably from downscaled GCM to GCM, thus demonstrating the value of
an ensemble. The efficiency in which HCW is realized in favorable
environments also varies considerably across the eight downscaled GCMs.