CMIP6 model fidelity in capturing the Southern Hemisphere storm track
and its connections with low-frequency variability
Abstract
Storm tracks are a key component of global atmospheric circulation.
Their influence ranges from macro- to mesoscale dynamics, from
large-scale movement of heat and momentum to extreme weather events. The
scale of their impact makes understanding storm track dynamics critical
to forecasting and climate projections. In this study, we assess CMIP6
historical experiment fidelity to observations of the Southern
Hemisphere storm track. Specifically, storm track climatology,
variability, and its interactions with low-frequency variability, with
the aim of providing confidence for projections of future climate. We
find CMIP6 models replicate results from the ERA-5 reanalysis with high
fidelity in some regards; namely, capturing climatology of the 500hPa
geopotential height field, the role of large-scale variability, and the
baroclinic connection with high-frequency variability. However, models
fail to capture the magnitude and variability of the storm track,
particularly canonical zonal asymmetry. Our results indicate the
importance of the storm track is underestimated in CMIP6.