Oceanographic equipment developed by underwater technology company Sonardyne will be used as part of a $2-million scientific study of disruptive ocean currents in the US Gulf of Mexico.
The multi-year deployment, led by the University of Rhode Island (URI)’s Graduate School of Oceanography, will monitor the Loop Current System (LCS) using Sonardyne’s Pressure Inverted Echo Sounders (PIES).
The LCS is the dominant ocean circulation feature in the Gulf of Mexico. It influences all ocean processes in the Gulf and has implications for a wide range of human and natural activities, from oil exploration to coastal eco-systems, but, knowledge of its underlying dynamics is limited. URI’s initial study aims to improve the understanding and prediction of the LCS by deploying a seabed network of PIES plus near-bottom current meters to monitor the central Gulf’s deep waters.
PIES work by transmitting an acoustic pulse from an instrument on the seabed upwards. The pulse is reflected off the water-air boundary at the sea surface and returns back down to the seabed where it is detected by the PIES. This enables an exact measurement of the two way signal travel time to be calculated. At the same instant, an accurate measurement of depth is made using highly precise internal pressure sensors. Combining data from an array of PIES instruments and near bottom current meters with historic water profile data can be used to calculate currents throughout the full water column, Sonardyne explains.
A total of 25 of Sonardyne’s and URI’s own PIES and current meters will be deployed this summer, in waters down to 3,500 metres depth, with an initial data retrieval using acoustic through-water communications to a surface vessel planned for autumn 2019. Instrument recovery is scheduled for autumn 2020. The results of this study will be used to inform how best to deploy a larger array for a planned 10-year-long research campaign.
URI’s LCS study is being funded by the US National Academies of Sciences, Engineering and Medicine’s Gulf Research Programme, which was founded in 2013, as part of the legal settlements with companies involved in the 2010 Deepwater Horizon oil spill. The long term objective is to improve forecasts of the LCS in order to increase the safety of operations in the Gulf.