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WRF Rainfall Parameterisation and Verification
Expanded Title:Rainfall and temperature are the main measures of numerical weather prediction (NWP) models. As computer processing capacity increases mesoscale models are being used more frequently for forecasting purposes and downscaling global and regional NWP models. This study used the Weather Research and Forecast Model (WRF) to simulate and verify rainfall, the PyTopkapi model for hydrological modelling, and the WRFChem to simulate the emission and assess its impact on rainfall. The main aim was to determine which parameterisation scheme works best under local conditions for producing accurate model results of precipitation events. Three case studies were selected viz Berg River catchment (Western Cape) and Liebergsvlei catchment (Free State) for rainfall simulation, and the industrialised Highveld region to run WRFChem model. Each catchment required different schemes to suitably model daily rainfall when running 12km model domains. Liebenbergsvlei results show that convective schemes trigger too early in the day and cause excessive rain days. Subsequently and WRF is currently inadequate at modelling convective rainfall over the Eastern Part of South Africa at this resolution and improvements to the model are required when modelling at this resolution. While the Betts-Miller-Janjic convective scheme, with either the WSM3 or Lin microphysics was suitable for the Berg River, these schemes did not perform well for Liebenbergsvlei.
Date Published:01/11/2014
Document Type:Research Report
Document Subjects:Water Resource Management/IWRM - Planning and development
Document Keywords:Climate, Hydrology
Document Format:Report
Document File Type:pdf
Research Report Type:Standard
WRC Report No:2162/1/14
ISBN No:978-1-4312-0598-1
Authors:Weston M; Kagoda P
Project No:K5/2162
Originator:WRC
Organizations:EScience Associates (PTY) LTD.
Document Size:9 952 KB
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