Reassessing the Value of Regional Climate Modeling Using Paleoclimate Simulations

Edward Armstrong,Peter O Hopcroft,Paul J Valdes

doi:10.1029/2019gl085127

Edward Armstrong, Peter O Hopcroft + Show 1 more

Open Access

https://doi.org/10.1029/2019gl085127

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Abstract

AbstractRegional climate models (RCMs) are often assumed to be more skillful compared to lower‐resolution general circulation models (GCM). However, RCMs are driven by input from coarser resolution GCMs, which may introduce biases. This study employs versions of the HadAMB3 GCM at three resolutions (>50 km) to investigate the added value of higher resolution using identically configured simulations of the preindustrial (PI), mid‐Holocene, and Last Glacial Maximum. The RCM shows improved PI climatology compared to the coarse‐resolution GCM and enhanced paleoanomalies in the jet stream and storm tracks. However, there is no apparent improvement when compared to proxy reconstructions. In the high‐resolution GCM, accuracy in PI climate and atmospheric anomalies are enhanced despite its intermediate resolution. This indicates that synoptic and mesoscale features in a RCM are influenced by its low‐resolution input, which impacts the simulated climatology. This challenges the paradigm that RCMs improve the representation of climate conditions and change.

Highlights

Regional climate modeling (RCM), termed regional dynamic downscaling, is an important tool for providing high‐resolution climate in a limited area
We focus only on resolutions ranging from approximately 3° to 50 km
Each model is derived from the same parent general circulation models (GCM) (HadCM3B) and comprises the same atmospheric physics, except for resolution‐ dependent parameters such as horizontal diffusion

Summary

Introduction

Regional climate modeling (RCM), termed regional dynamic downscaling, is an important tool for providing high‐resolution climate in a limited area. A number of paleostudies highlight the added value of a RCM when compared to their lower resolution‐driving model for periods throughout the Holocene (Brayshaw et al, 2009; Gomez‐Navarro et al, 2011; Gomez‐Navarro et al, 2013; Renssen et al, 2001; Russo & Cubasch, 2016; Strandberg et al, 2014) and Last Glacial Maximum (LGM; Jost et al, 2005; Ju et al, 2007; Ludwig et al, 2017; Strandberg et al, 2011) This added value is due to an improvement in the depiction of feedbacks and physical processes. Studies show that higher‐resolution climate models better represent moisture transport, intensity, structure, and variability of ARMSTRONG ET AL

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