29 January 2018

Exploring a Variable-Resolution Approach for Simulating Regional Climate in the Rocky Mountain Region Using the VR-CESM

Precipitation transects across the Rocky Mountains from VR-CESM, uniform-resolution CESM, observations, and CRCM5

A comprehensive investigation was performed of how the variable-resolution CESM simulates the Rocky Mountain region when compared with uniform-resolution simulations, observations, and a regional model (CRCM5). This study focused on topographically-sensitive quantities, particularly mountain snowpack, temperatures, and rain-on-snow events.


Variable-resolution global climate modeling systems provide significant value in regions of strong topographic variability, such as the Rocky Mountain region. This paper assesses the performance of a global modeling system as it is pushed down to resolutions typical of regional climate modeling systems.


In this study, the variable-resolution CESM (VR-CESM) is demonstrated to be able to accurately simulate key climatological variables and their associated seasonality in the Rocky Mountains.  Using a suite of snow-related metrics related to precipitation, snow cover, snow water equivalent, rain-on-snow events, model performance is observed to be significantly improved over uniform resolution simulations, and comparable to analogous regional climate model simulations.  VR-CESM was demonstrated to capture the observed occurrence frequency of heavy precipitation and rain-on-snow (ROS) events. Nonetheless, it was shown that although VR-CESM overestimated winter precipitation, it underestimated snow water equivalent peaks in the Rocky Mountains. Further work is needed to understand the biases related to snow variables in VR-CESM.

Xiaohong Liu
University of Wyoming
Lin, Z.  2017.  "Exploring a Variable-Resolution Approach for Simulating Regional Climate in the Rocky Mountain Region Using the VR-CESM."  Journal of Geophysical Research: Atmospheres 122(20): 10939-10965, doi:10.1002/2017jd027008.