Shamal winds and waves in the Arabian Gulf: variability and trends (1940–2024)

Abstract This study examines the monthly and annual climatology and long–term trends of high intensity Shamal winds and waves across the Gulf during 1940–2024 using ERA5 reanalysis. Winds and waves are analysed for both total conditions and Shamal–only conditions within three subregions: the northern Gulf (NG), middle Gulf (MG), and southern Gulf (SG). The annual climatology is dominated by northwesterly Shamals that exert first–order control on the wave field. Mean high Shamal wind speeds are typically 7– $$9.8~\textrm{m}~\textrm{s}^{-1}$$ along the basin axis, with 99th percentile values exceeding $$15~\textrm{m}~\textrm{s}^{-1}$$ . Under Shamal forcing, mean $$\textrm{H}_{\textrm{s}}$$ reaches $$1.0-1.5~\textrm{m}$$ in NG and $$1.5-2.0~\textrm{m}$$ in MG and SG, while extreme $$\textrm{H}_{\textrm{s}}$$ exceeds $$3.5~\textrm{m}$$ in MG and SG. Monthly cycles peak in winter and weaken in summer, and the mean state is consistently stronger under Shamal-only conditions. Long–term trends reveal a seasonally modulated decline, most pronounced during summer. NG and MG show coherent June–August decreases in both wind speed and $$\textrm{H}_{\textrm{s}}$$ , whereas SG exhibits weaker summer reductions but a modest strengthening during late autumn. Collectively, these results highlight a progressive attenuation of high Shamal forcing and a reorganization of seasonal wind–wave interactions across the Gulf over the past eight decades. These changes in wind and wave forcing have implications for the seasonal distribution of coastal exposure to energetic conditions across the Gulf.