Reverse circulation in Bahía Santa Elena, North Pacific of Costa Rica

Abstract This work describes the water circulation of Bahia Santa Elena using velocity fields and hydrographic data obtained from a ship-mounted Acoustic Doppler Current Profiler and a vertical profiler Conductivity-Temperature-Depth sonde, during two campaigns in August and October of 2019. Data were taken in a cross-bay transect in the main channel of the Bahia Santa Elena during a complete tidal cycle. The hydrographic data obtained during the two sampling campaigns suggest a reverse estuarine circulation; tidally averaged values of density and water velocities revealed a dense outflow at the bottom layer in the bay. This is the first description of an inverse estuary circulation pattern in Costa Rica and the second in Central America. Understanding the hydrographic properties of the bay is crucial for undertaking future research projects on water quality and biological communities.