Seasonal Hydrographic Characteristics and Estimation of Geostrophic Currents in the Central Red Sea Region Using ARGO Float Observations

The current study is carried out in the central Red Sea region, an area of significant oceanographic importance because of the presence of several persistent eddies. The study is based on Argo float observations with a temporal resolution covering the period from April 2010 until January 2011. Temperature and salinity profiles were used to describe the seasonal distribution of hydrographic structure and estimate the geostrophic velocity field. The observations indicate that seasonal variabilities control hydrographic parameters above the permanent pycnocline layer. Sea surface temperature and salinity vary from 27 to 32.5 °C and 38.5–39.4 psu during winter and summer, respectively. The stratification features and water masses during summer and winter are considered. The summer structure is characterized by a shallow mixed layer (30–40 m), while it is deeper (100 m) during winter. The Gulf of Aden Intermediate Water subsurface intrusion is observed to reach the central Red Sea during summer. Satellite altimetry data of sea level anomaly in conjunction with temperature and salinity observations are also used to estimate the surface geostrophic velocity over the central Red Sea. The results obviously reflected the dominance of cyclonic and anticyclonic eddies. The vertical geostrophic flows are variable according to the eddies pattern in the region. The influence of the eddy can reach a depth of 300 m in the central Red Sea, and a rise of the isolines can be observed from a similar depth, uplifting the isolines to a depth of almost 50 m.