Topoclimate and diurnal cycle of summer rain over the Ethiopian highlands in a convection‐permitting simulation

作者：Emnet Negash, Bert Van Schaeybroeck, Piet Termonia, Michiel Van Ginderachter, Kwinten Van Weverberg, Jan Nyssen · 发表于：International Journal of Climatology · 年份：2023 · DOI：10.1002/joc.8334 · 被引用次数：5 · 研究领域：Climate variability and models、Precipitation Measurement and Analysis、Plant Water Relations and Carbon Dynamics

Abstract Topoclimate, orographically enhanced rain on windward slopes and leeward rain shadows, control rainfall variability in tropical mountains. Such variability may cause a substantial societal impact in populated highlands such as in Ethiopia. This study aims at understanding the rainfall diurnal cycle and the orographic driving factors over the Ethiopian highlands using the ALARO‐0 regional climate model at convection‐permitting resolution, over a period of 21 years. While the evaluation against satellite‐based observations shows a too early onset of the model diurnal cycle and a too low nocturnal rainfall, several conclusions can be drawn from the model simulations presented here. Elevation is the most important determining factor for modelled rainfall with increased average rainfall and rainfall per rainfall event towards higher elevations. Ethiopia's simulated summer rain exhibits a pronounced diurnal cycle with the highest rainfall occurring during the early afternoon hours and the minimum values occurring in the late night. Average rainfall and rainfall per rainfall event are substantially larger on the windward sides than on the leeward sides of the mountains, except during the peak hours. The diurnal cycles of temperature and humidity start earlier in the morning and recede later than the cycles of wind speed and rainfall. Moreover, rainfall peaks occur earlier in the day at higher elevations, and at night in valleys and in Afar Triangle. Rain intensities around ...