Oh, SG; Sushama, L (2020). Fluvial inundation parameterization in climate model and its effects on regional climate: a case study of the 2009 Red River spring flood. THEORETICAL AND APPLIED CLIMATOLOGY, 141(2-Jan), 699-714.

This study introduces a simple and newly developed fluvial inundation parameterization using high-resolution climate model and investigates its impacts on regional climate. The 2009 Red River spring flood is selected as a case study and this approach is tested with the regional climate model, Global Environment Multiscale (GEM) version 4.8 with 10 km resolution, and Canadian Digital Surface Model (CDSM) elevation (similar to 20 m). To investigate the impacts of fluvial inundation on regional climate, the sensitivity experiments using different initial conditions for soil moisture are conducted with 1 km resolution through a three-step one-way nesting approach. Generally, new approach can capture the development-decay of fluvial inundation, similar to MODIS observation. The reasonable statistic values (probability of detection, 0.71; false alarm ratio, 0.26) are found on April 15-22 when occurred the largest MODIS-observed fluvial inundation. In sensitivity experiments, the increase of soil moisture by flooding can induce the decrease of albedo, leading to the increase in absorbed solar radiation energy at surface. Most of the absorbed energy is used by the latent heat flux, inducing the temperature cooling and moisture increase. These changes are larger in daytime than nighttime and are statistically significant in only 2 months (May-June) from the flooding, which contribute to the improvement of temperature simulation. The significant decrease and increase of precipitation in northeastern and southeastern regions away from the flooded region, respectively, are noted post-flooding. These changes are closely associated with the decrease and increase of moist static energy by moisture divergence and convergence, respectively.