Kwame Karikari Yamoah PhD Student, Global Change Research Institute (CzechGlobe), Czech Republic.

Title: Uncertainties in highresmip models in simulating rainfall over West Africa based on the choice of reference data

Abstract: The scarcity of high-quality in situ observations with adequate spatiotemporal coverage remains a major constraint for robust climate model evaluation over West Africa. Consequently, satellite-based and reanalysis products are frequently employed as alternative reference datasets, despite their differing strengths and limitations, which can lead to inconsistent model assessment outcomes. In this study, we evaluate the performance of eight High-Resolution Model Intercomparison Project (HighResMIP) simulations in reproducing West African rainfall characteristics over the period 1983–2014 using five reference datasets. Model performance is assessed in terms of the annual cycle, interannual variability, summer monsoon precipitation (June–July–August–September; JJAS), and extreme rainfall behavior across the Sahel, the Guinea Coast, and the broader West African region. The results indicate that, while the models capture key aspects of the seasonal rainfall cycle, their performance declines in simulating extreme precipitation during the summer monsoon. This reduced performance is evident across the full West African domain and its climatic zones, with pronounced wet biases and increased uncertainty linked to outliers in JJAS rainfall extremes. Our findings highlight the sensitivity of model evaluation to the choice of reference dataset and underscore persistent challenges in representing extreme rainfall processes in high-resolution climate models over West Africa.