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By: Dr. Russell Glazer
Over jap Africa a monumental geological course of is going on that can ultimately cut up the nations of Somalia, Kenya, Ethiopia, Tanzania, and Mozambique from the remainder of Africa. The African tectonic plate is spreading alongside a line from the Crimson Sea within the north to Mozambique within the south, forming an infinite valley surrounded by among the tallest mountains in Africa. On the centre of this Nice Rift Valley sits the second largest freshwater lake on the planet, Lake Victoria.
Lake Victoria from the ISS, https://en.wikipedia.org/wiki/Lake_Victoria
Lake Victoria additionally occurs to be located on the equator and is topic to year-round thunderstorms which have a very distinct diurnal cycle. Throughout the daytime, photo voltaic heating warms the land surrounding the lake at a quicker charge than the lake itself creating an area lake breeze circulation which focuses thunderstorms across the periphery of the lake. As soon as photo voltaic heating recedes within the night this circulation begins to reverse as a result of thermal inertia of the lake and thunderstorm exercise migrates to the lake itself in reference to a land breeze. These nocturnal and morning thunderstorms are sometimes hazardous to fishers on the lake with annual studies of about 1000 fatalities from climate associated accidents on the lake every year (Watkiss et al. 2020). With round 30 million individuals dwelling in and round Lake Victoria’s shores, and over 200,000 fishers working on the lake (LVFO 2022), there’s a clear want for environment friendly monitoring and communication of meteorological hazards within the Lake Victoria basin (LVB).
Waterbus catamaran capsized close to Kenyan coast 2 Might 2020, Roberts et al. (2022)
The latest multinational Excessive Influence Climate Lake System (HIGHWAY) program (Roberts et al. 2022) sought to deal with these wants by growing new climate warning techniques for the area and fostering collaboration with native climate service businesses. The mission included area campaigns and the set up of a climate radar in Entebbe, Uganda alongside the northern coast of Lake Victoria which augments one other climate radar alongside the southern coast operated by Tanzania. These radars enhance the power of forecasters to see hazardous climate over the lake and supply higher warnings to fishers.
Lightning strike density throughout the afternoon (a) and night-time (b) within the Lake Victoria area from the Earth Networks World Lightning Community dataset. Determine 3 from Roberts et al. (2022).
Latest analysis efforts have additionally been targeted on modelling research of hazardous thunderstorms over the LVB similar to Thiery et al. (2016), which used excessive decision mannequin simulations to indicate that sturdy daytime thunderstorm exercise over land is expounded to subsequent nighttime sturdy storm exercise. Robust daytime thunderstorms will cool the land surrounding the lake, most notably by chilly swimming pools, thereby weakening the daytime temperature gradient between the lake and land. Nonetheless, throughout the subsequent nighttime, the cooler land floor results in an enhanced gradient towards the lake, and this results in an enhanced native land breeze.
As a part of the Local weather Extremes over Lake Victoria Primary (ELVIC; van Lipzig et al. 2023) mission, high-resolution (3km) regional local weather simulations had been carried out with the RegCM model 4.7.1 on the Worldwide Centre for Theoretical Physics (ICTP) in Trieste, Italy (Glazer et al. 2023). This 10-year simulation of the LVB supplied a possibility to review hazardous nocturnal thunderstorms over the lake with a high-resolution mannequin that may resolve particular person thunderstorms and convection. Within the simulations, convection is explicitly produced with out a large-scale convection scheme, and the lake is coupled to the ambiance by a lake mannequin. Within the examine by Glazer et al. (2023) the mechanisms resulting in excessive precipitation occasions over the lake at night time had been analyzed by compositing excessive, regular and dry occasions. Chilly swimming pools seem to play bigger function within the propagation or triggering of storms within the excessive composite in comparison with regular precipitation occasions. Apparently, convective instability seems related in every of the intense and regular composites, nevertheless the intense composite reveals better dynamical convergence over the lake which might be the results of a stronger land breeze or the results of chilly swimming pools. This stronger forcing for triggering storms could also be a key ingredient for sturdy convection at night time over Lake Victoria.
References:
Glazer, R., E. Coppola, F. Giorgi, (2023) Understanding nocturnally-driven excessive precipitation occasions over Lake Victoria in a convection-permitting mannequin. Mon. Wea. Rev. (In evaluation)
Lake Victoria Fisheries Group. (2022) STATUS OF FISHING EFFORT ON LAKE VICTORIA UP TO 2016. Downloaded from https://www.lvfo.org/content material/documents-0.
Lipzig, N.P.M.v., Walle, J.V.d., Belusic, D. et al. (2023) Illustration of precipitation and top-of-atmosphere radiation in a multi-model convection allowing ensemble for the Lake Victoria Basin (East-Africa). Clim. Dyn. https://doi.org/10.1007/s00382-022-06541-5.
Roberts, R. D., and Coauthors, 2022: Taking the HIGHWAY to Save Lives on Lake Victoria. Bull. Amer. Meteor. Soc., 103, E485–E510, https://doi.org/10.1175/BAMS-D-20-0290.1.
Thiery W., E. L. Davin, S. I. Seneviratne, Okay. Bedka, S. Lhermitte, and N. P. van Lipzig, 2016: Hazardous thunderstorm intensification over Lake Victoria. Nat. Commun., 7, 12786, https://doi.org/10.1038/ncomms12786.
Watkiss, P., R. Powell, A. Hunt, F. Cimato 2020: The Socio-Financial Advantages of the HIGHWAY mission. Technical Report (UK Met Workplace, World Meteorological Group, UKaid).
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