Influences of Orography on Banded and Cellular Lake- and Sea-Effect Systems in Idealized Simulations

Some of the most impactful lake-effect systems in the world are produced over Lake Ontario and the Sea of Japan, where they exhibit a spectrum of morphologies and a wide range of terrain interactions. While lake-effect systems produced over Lake Ontario are often banded and interact with the modest, 500-m Tug Hill, Sea of Japan systems commonly display a cellular morphology, and are influenced by the formidable, 2000-m mountains along Japan’s west coast. Observations show that banded lake-effect systems are generally characterized by small orographic ratios (mountain to lowland precipitation ratio), while cellular lake-effect systems usually have large orographic ratios, indicating differences in the way these two morphologies interact with terrain. In this study, we seek to further the understanding of differences in the development, maintenance, and terrain interaction of banded and cellular lake-effect systems using idealized large-eddy simulations. Idealized large-eddy simulations remove complexities, such as complex coastal geometry and unresolved boundary layer circulations, allowing for individual lake-/sea-effect and orographic processes to be isolated, examined, and quantified. Simulations with idealized representations of Lake Ontario, the Sea of Japan, the Tug Hill, and the mountains along the west coast of Japan are analyzed to conduct this study. Results from this study will help to improve the prediction of lake-effect precipitation and understanding of shallow, intense orographic precipitation.