Variability of Euphotic Zone Depth in the Arabian Sea Over the Period 1998–2023

Abstract This study provides a comprehensive assessment of the spatial and temporal variability of euphotic zone depth (Zeu) across the Arabian Sea from 1998 to 2023, focusing on three sub‐regions: the Northern Arabian Sea (NAS), South Eastern Arabian Sea (SEAS), and South Western Arabian Sea (SWAS), using satellite‐derived data sets. The analysis reveals that Zeu variability occurs on interannual, intra‐annual, and decadal timescales. Annual mean Zeu values across the basin ranges from 6 to 80 m, reflecting considerable spatial heterogeneity in water clarity. Regionally, NAS recorded Zeu values ranging from ∼10 to 62 m, SEAS from ∼10 to 74 m, and SWAS from ∼12 to 72 m. Empirical Orthogonal Function (EOF) analysis confirmed that interannual variability accounts for 21.57% of the total variance. Interannual variability is primarily modulated by the Indian Ocean Dipole (IOD), followed by the El Niño–Southern Oscillation (ENSO), particularly in the SEAS and SWAS regions. Zeu in the NAS showed a significant lagged response, with Principal Component (PC1) lagging Dipole Mode Index (DMI) and ENSO by approximately 10 and 8 months, respectively. A statistically significant positive trend in Zeu was observed across the basin and within all three sub‐regions, with the NAS exhibiting the strongest increase. Seasonal trend analysis showed increasing Zeu trends across all seasons, with the NAS during the ON (October–November) season demonstrating the highest trend (0.47 m/year). Overall, this work offers the first detailed analysis of Zeu variability in the Arabian Sea using multi‐sensor satellite data.