Toward Operational High-Resolution Forecasting: First Application of a Spectral Element Limited-Area Model

In this presentation, we introduce a new limited-area model (LAM) that employs the spectral element method (SEM) on a cubed-sphere grid. This is the first SEM-based LAM developed for dynamical downscaling applications. As the limited-area version of the Korean Integrated Model (KIM)—Korea’s operational global weather forecasting model since 2020—the LAM shares core components with the global KIM, including the non-hydrostatic dynamical core and scale-aware physics, differing only in the simulation domain.

At the previous European Meteorological Society Annual Meeting, we demonstrated that our lateral boundary condition design for SEM maintains numerical stability beyond 10 days of integration in idealized test runs nested within global KIM simulations. Since then, additional experiments have confirmed that the LAM can stably perform 1 km resolution simulations over the Korean Peninsula using 6-hourly lateral boundary conditions derived from 8 km resolution global forecasts. The model has also demonstrated stable performance when driven by ERA5 reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF), underscoring its potential as a general-purpose downscaling tool. These results suggest that an SEM-based LAM can serve as an efficient and robust dynamical downscaling system, especially given that our simulations utilized minimal linear relaxation at the lateral boundaries and no spectral nudging.

With the ultimate goal of supporting high-resolution short-range forecasting, we have also developed a test operational scenario aligned with the operational forecast schedule of the global KIM model which will provide the initial and boundary conditions for the LAM. Additionally, we present the ongoing development of a dedicated data assimilation system for the LAM, designed to directly assimilate reflectivity and radial velocity observations from Korea’s ground-based radar network.