Spatial and temporal variability of the evaporation duct in the Gulf of Aden

An evaporation duct climatology is constructed for the Gulf of Aden using a 31-year high-resolution data set from the climate reanalysis product National Centers for Environmental Prediction Climate Forecast System Reanalysis. The climatology reveals spatio-temporal heterogeneity in the evaporation duct height (EDH) regulated by the strong interplay between the seasonal monsoon reversals and the related atmospheric and oceanic responses. It also reveals that the Gulf of Aden exhibits a special EDH distribution that is distinct from the adjacent Arabian Sea when the south-west monsoon dominates the gulf. Under these conditions, the EDH of the entire gulf is significantly higher than that of the adjoining Arabian Sea. A cliff-style EDH drop (referred to as the EDH cliff) forms at the mouth of the Gulf of Aden. Furthermore, the influence of the EDH cliff on marine radar was investigated using a ray-optics method. Based on the analysis, it was found that the local EDH significantly affects the radar detection ability beneath the evaporation duct for ships sailing in the Gulf of Aden.