Representation of precipitation and top-of-atmosphere radiation in a multi-model convection-permitting ensemble for the Lake Victoria Basin (East-Africa)

• Published in: Climate dynamics Vol. 60; no. 11-12; pp. 4033 - 4054
• Main Authors: Lipzig, Nicole P. M. van, Walle, Jonas Van de, Belušić, Danijel, Berthou, Ségolène, Coppola, Erika, Demuzere, Matthias, Fink, Andreas H., Finney, Declan L., Glazer, Russell, Ludwig, Patrick, Marsham, John H., Nikulin, Grigory, Pinto, Joaquim G., Rowell, David P., Wu, Minchao, Thiery, Wim
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2023; Springer; Springer Nature B.V
• Subjects: Atmosphere; Atmospheric convection; Atmospheric models; Climate; Climate models; Climatic extremes; Climatology; Convection; Convection permitting simulations; Convective systems; CORDEX Flagship Pilot Study; Diurnal cycle; Diurnal variations; Earth and Environmental Science; Earth and Related Environmental Sciences; Earth Science with specialization in Physical Geography; Earth Sciences; Environmental aspects; Equatorial Africa; Extreme weather; Extreme weather events; Geophysics/Geodesy; Geovetenskap med inriktning mot naturgeografi; Geovetenskap och miljövetenskap; Kilometer-scale resolution; Lake basins; Lake Victoria basin; Lakes; Modelling; Natural Sciences; Naturvetenskap; Numerical weather forecasting; Oceanography; Precipitation; Precipitation (Meteorology); Radiation; Rainfall; Rainfall intensity; Regional climate models; Regional climates; Representations; Seasonal variation; Spatial distribution; Tropical deep convection; Africa; Lake Victoria; CORDEX Flagship Pilot Study; Tropical deep convection; Lake Victoria basin; Kilometer-scale resolution; Regional climate models; Extreme weather events; Convection permitting simulations; Equatorial Africa
• ISSN: 0930-7575; 1432-0894; 1432-0894
• DOI: 10.1007/s00382-022-06541-5

The CORDEX Flagship Pilot Study ELVIC (climate Extremes in the Lake VICtoria basin) was recently established to investigate how extreme weather events will evolve in this region of the world and to provide improved information for the climate impact community. Here we assess the added value of the convection-permitting scale simulations on the representation of moist convective systems over and around Lake Victoria. With this aim, 10 year present-day model simulations were carried out with five regional climate models at both PARameterized (PAR) scales (12–25 km) and Convection-Permitting (CP) scales (2.5–4.5 km), with COSMO-CLM, RegCM, AROME, WRF and UKMO. Most substantial systematic improvements were found in metrics related to deep convection. For example, the timing of the daily maximum in precipitation is systematically delayed in CP compared to PAR models, thereby improving the agreement with observations. The large overestimation in the total number of rainy events is alleviated in the CP models. Systematic improvements were found in the diurnal cycle in Top-Of-Atmosphere (TOA) radiation and in some metrics for precipitation intensity. No unanimous improvement nor deterioration was found in the representation of the spatial distribution of total rainfall and the seasonal cycle when going to the CP scale. Furthermore, some substantial biases in TOA upward radiative fluxes remain. Generally our analysis indicates that the representation of the convective systems is strongly improved in CP compared to PAR models, giving confidence that the models are valuable tools for studying how extreme precipitation events may evolve in the future in the Lake Victoria basin and its surroundings.