Correcting Multivariate Biases in RCM Boundaries: How are Synoptic
Systems impacted over the Australian Region?
Abstract
Synoptic climatology, which connects atmospheric circulation with
regional environmental conditions, is pivotal to understanding climate
dynamics. While regional climate models (RCMs) can reproduce key
mesoscale precipitation patterns, biases related to synoptic circulation
from the driving model, typically global climate models (GCMs), often
remain unaddressed. This study examines the influence of correcting
systematic bias in RCM boundaries on the representation of Australian
synoptic systems. We utilize a structural self-organizing map (SOM) to
evaluate the frequency, persistence, and transitions of daily synoptic
systems. Our findings reveal that an RCM with multivariate
bias-corrected boundaries improves the representation of synoptic
systems compared to the driving GCM, or an RCM with uncorrected or
simply bias-corrected boundaries, particularly in reference to the
frequency of systems identified. This demonstrates that appropriately
correcting RCM boundary conditions helps correct many of the circulation
errors inherited from the driving GCM but not all.