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Abstract

Tropical easterly waves (TEWs) play a key role in rainfall variability and act as precursors to tropical cyclones in the North Atlantic. However, the origin of TEW-related precipitation remains insufficiently explored. This study presents a 39-year (1985–2023) climatology of TEWs using a curvature vorticity-based tracking method applied to a downscaled ERA5 dataset, combined with a Lagrangian moisture source analysis. An average of 41 ± 5 TEWs per year is identified, with a pronounced peak during July–September. TEWs propagate westward at approximately 8 m/s, with the highest activity across the main development region of tropical cyclones. TEWs account for 1–7 % of annual rainfall across the basin, with peaks spatially coinciding with areas of highest wave activity. Moisture source diagnostics reveal three distinct TEW regimes. Near the African coast, moisture is primarily derived from the eastern tropical Atlantic and continental Africa, whereas waves in the central Atlantic and Caribbean region increasingly rely on long-distance zonal transport from the eastern and central tropical Atlantic, consistent with the wave lifecycle. The analysis also reveals the trade and easterly winds as the primary moisture transport mechanisms, while area-average moisture uptake and associated precipitation show no statistically significant positive long-term trends. Meanwhile, the mean water vapour residence time for TEW-related precipitation is about 3.6 days, slightly longer than for tropical cyclones. This study extends previous climatologies and contributes to enhancing the understanding of TEW-related hydroclimate processes in the tropical North Atlantic.