WRF Simulations of Extreme Rainfall over Uganda’s Lake Victoria Basin: Sensitivity to Parameterization, Model Resolution and Domain Size
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Date
2020
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Geoscience and Environment Protection
Abstract
Rainfall extremes have strong connotations to socio-economic activities and human well-being in Uganda’s Lake Victoria Basin (LVB). Reliable prediction and dissemination of extreme rainfall events are therefore of paramount im-portance to the region’s development agenda. The main objective of this study was to contribute to the prediction of rainfall extremes over this region using a numerical modelling approach. The Weather Research and Forecasting (WRF) model was used to simulate a 20-day period of extremely heavy rainfall that was observed in the March to May season of 2008. The underlying interest was to investigate the performance of different combinations of cumulus and mi-crophysical parameterization along with the model grid resolution and do-main size. The model output was validated against rainfall observations from the Tropical Rainfall Measuring Mission (TRMM) using 5 metrics; the rain-fall distribution, root mean square error, mean error, probability of detection and false alarm ratio. The results showed that the model was able to simulate extreme rainfall and the most satisfactory skill was obtained with a model se-tup using the Grell 3D cumulus scheme combined with the SBU_YLin micro-physical scheme. This study concludes that the WRF model can be used for simulating extreme rainfall over western LVB. In the other 2 regions, central and eastern LVB, its performance is limited by failure to simulate nocturnal rainfall. Furthermore, increasing the model grid resolution showed good po-tential for improving the model simulation especially when a large domain is used.
Description
Keywords
Extreme Rainfall, WRF, Parameterization, Model Resolution, Domain Size
Citation
Opio, R., Sabiiti, G., Nimusiima, A., Mugume, I., & Sansa-Otim, J. (2020). WRF Simulations of Extreme Rain-fall over Uganda’s Lake Victoria Basin: Sen-sitivity to Parameterization, Model Resolu-tion and Domain Size. Journal of Geoscience and Environment Protection, 8, 18-31. https://doi.org/10.4236/gep.2020.84002