A Limited Area Modeling Capability for the Finite‐Volume Cubed‐Sphere (FV3) Dynamical Core and Comparison With a Global Two‐Way Nest

Abstract

Abstract The development of a limited area model (LAM) capability for the nonhydrostatic Finite‐Volume Cubed‐Sphere (FV3) dynamical core is described and compared with a globally nested approach featuring two‐way feedback. Comparisons of the computational performance of the LAM relative to the two‐way nest reveal that the LAM configuration exhibits considerable improvement in efficiency. High‐resolution (i.e., 3‐km) LAM and nest configuration forecasts covering a 1‐month period show statistically comparable results for most parameters. Forecast differences between the two configurations primarily arise in the upper air temperature and height fields, which show a statistically significant increase in the magnitude of negative biases in geopotential height and upper‐air temperature using the LAM configuration relative to the nest at forecast lead times >24‐h. Precipitation forecasts over the full 60‐h forecast period are also evaluated and depict no statistically significant differences between the two configurations, with the nest configuration exhibiting slightly improved scores. Overall results suggest that while the FV3 LAM approach can introduce degradations into the forecast relative to the two‐way interactive nest at lead times >24‐h, these errors are generally small in magnitude and are accompanied by considerable improvement in computational efficiency.

Keywords

• limited area model
• UFS
• FV3
• numerical weather prediction
• regional model