Improved Current Estimates from Spar Buoy-Mounted ADCP Measurement Station: A Case Study in the Ligurian Sea

Andrea Bordone,Tiziana Ciuffardi,Roberto Bozzano,Paola Picco,Antonio Schirone,Sara Pensieri,Giancarlo Raiteri,Francesca Pennecchi

doi:10.3390/jmse9050466

Abstract

Current measurements in the open sea are generally acquired by Acoustic Doppler Current Profilers (ADCPs). In the case of ADCPs mounted on spar buoy, current profiles require to be post-processed, to properly take into account the buoy influence: in fact, ADCP compass may reflect alterations induced by the metal structure of the buoy and apparent currents can occur due to the large displacement of the platform. Uncertainty analysis is finally required to properly consider both these effects and to compute robust velocity estimates. A new methodology is tested for a measurement station in the Ligurian Sea, where an ADCP was mounted on the surface buoy of the W1-M3A (Western 1 Mediterranean Moored Multisensor Array) oceanographic observatory, facing upwards at the depth of about 40 m. Marine current numerical models and historical data in the area have been used as a basis for comparison to test the consistency of the proposed method. A very good agreement is obtained. Only minor discrepancies are reported (e.g., monthly averages from the reference model slightly underestimate the west-east current component along the entire profile), but, in general, the application of the proposed methodology ensures that the spar buoy-mounted ADCP system is able to provide reliable measurements for oceanographic studies and validation of 3D hydrodynamic models.

Highlights

Current data are a major asset for oceanographic research both for validation and assimilation in hydrodynamic models
From the pressure measurements recorded on board of the Acoustic Doppler Current Profilers (ADCPs), the average depth of the head of the acoustic sensorofwas derived,during in order correctly scale the depths
Period associated with the centers of the various cells into which the current profile was divided

Summary

Introduction

Current data are a major asset for oceanographic research both for validation and assimilation in hydrodynamic models. Current monitoring is an essential tool for understanding ocean marine ecosystems, planning and securing maritime operations or designing offshore structures. The measurement of current is the basis for any resource assessment related to offshore renewable energy devices. Accurate current data can help in tracking sources of pollution, like chemical or sewage spills. Same data can be used to efficiently and reliably forecast oil spill trajectories or assess coastal water quality in general. Reliable information on current conditions and consequent monitoring are required for habitat restoration or coastal protection projects, especially considering the future spread of nature-based solutions (NBS)

Results

Discussion

Conclusion