Poster Title:Evaluation of physical schemes for the Weather Research and Forecasting (WRF) model over the United Arab Emirates
Full Name:MAHMOUD HUSSEIN
Affiliation / Institution:NCM
Abstract:To obtain reliable rainfall estimates using the Weather Research and Forecasting (WRF) model, it is essential to accurately parameterize sub-grid-scale physical processes. Improving the accuracy of rainfall estimates often involves using various combinations of physical parameterizations, collectively known as a physical ensemble, which generally yields more precise results than a single physics scheme. Building a WRF physical ensemble is crucial, as each physics scheme's performance often depends on related physical parameterizations due to the interconnected nature of atmospheric processes. Therefore, the ensemble's ability to accurately reproduce rainfall patterns relies on both its spread and mean performance. When selecting a physical scheme, certain criteria should be prioritized: it should be commonly used in research and operational forecasting, minimize error, effectively resolve local convective systems, and increase ensemble spread to provide a reliable estimate of uncertainty. In this study, WRF physical ensemble experiments are conducted and evaluated for each rainfall event, using combinations of three cumulus convection (CC) schemes (Kain–Fritsch, Betts–Miller–Janjic, and Grell–Devenyi), five microphysics (MP) schemes (Ferrier, WSM6, Thompson, Lin, and Kessler), and three planetary boundary layer (PBL) schemes (Yonsei University scheme, Mellor–Yamada–Janjic, and Asymmetric Convective Model). This approach results in a total of forty-five ensemble members across three one-way nested domains, implemented using WRF version 4.2 with the ARW core. The WRF physical ensemble was run and evaluated over the United Arab Emirates (UAE) for rainfall events influenced by various factors, including convective systems, frontal activity, and orographic effects. Among these events, an extreme rainfall event occurred during 2023-2024. The results of the forty-five-member WRF physical ensemble for rainfall were verified and analyzed against observed rainfall data from UAE meteorological stations. This analysis aimed to assess how effectively the ensemble spread encompassed observed values and how closely the ensemble average matched the observations. The quality of rainfall forecasts was evaluated both quantitatively and qualitatively.