Work

The Arabian Gulf Oscillation (AGO): A recurrent dipolar mode of mesoscale eddy variability in the Gulf

Year: 2026

Type: article

Abstract: This study investigates the spatial and temporal variability of sea surface height (SSH) and associated mesoscale dynamics in the Arabian/Persian Gulf over a 28-year period (1993–2020) using GLORYS12V1 ocean reanalysis dataset from the Copernicus Marine Environment Monitoring Service. Two low-SSH regions, identified near 28.5°N, 50°E (northern eddy) and 26.4°N, 53°E (southern eddy), were found to govern much of the Gulf's mesoscale variability. These regions are characterized by pronounced SSH gradients and elevated eddy kinetic energy (EKE), particularly during summer when wind speeds and air-sea heat fluxes peak. The eddies align with zones of intensified surface cooling and vertical mixing, suggesting a role in Gulf Deep Water formation, further explored in a parallel study. Seasonal analyses reveal a cyclonic summer circulation maintained by the Iranian Coastal Current and Gulf Coastal Current, which interact dynamically with the eddies and influence their development. On interannual timescales, SSH and EKE fields exhibit alternating intensification between the eddies, indicating asymmetric responses to regional dynamics and large-scale climate variability. EOF analysis reveals three dominant modes of SSH variability: a basin-scale north–south gradient (EOF1), a dipolar eddy mode (EOF2) linked to wind anomalies, and a southern eddy mode (EOF3) correlated with the Indian Ocean Dipole Mode Index (DMI). The dipolar variability and interannual asymmetries define a coherent, recurring oscillation in SSH and EKE between the two eddies. We propose this as the Arabian Gulf Oscillation (AGO), a previously undocumented low-frequency internal mode of the Gulf's mesoscale circulation, modulated by atmospheric forcing and climate variability. • The Arabian Gulf Oscillation (AGO): A previously undocumented dipolar SSH mode with alternating northern and southern eddies. • Mesoscale Eddies Identified: Two quasi-permanent mesoscale eddies located in the northern and southern Arabian Gulf. • Seasonal Evolution of Boundary Currents: Iranian and Gulf Coastal Currents form a low-SSH frontal zone in summer. • Eddy Kinetic Energy Reveals Interannual Variability: Eddy kinetic energy shows SSH-linked asymmetric eddy intensities. • Dominant Spatial Modes Linked to Wind and Climate Forcing: EOF analysis links SSH and climate indices.

Source: Journal of Marine Systems

DOI: 10.1016/j.jmarsys.2026.104182

Authors: Tariq Alrushaid, Fahad Al Senafi

Institution: Kuwait University

Language: English

Topic: Oceanographic and Atmospheric Processes

Subfield: Oceanography

Field: Earth and Planetary Sciences

Domain: Physical Sciences

SDGs: Climate action, Life below water

Open Access status: hybrid

Estimated APC paid: $3,510