ADCPs for coastal-ocean modelling: Insights from Multi-Decadal Deployments in the Orkney-Pentland Firth Region

Acoustic Doppler Current Profilers (ADCPs) are widely deployed to characterise tidal currents in energetic marine environments. While instruments and deployment techniques have improved reliability, data usability remains constrained by workflow, metadata, and archival practices. This study draws lessons from a multi-decadal archive of ADCP deployments across tidal energy sites in the Orkney and Pentland Firth region. With dozens of deployments conducted, less than half of datasets found were readily usable due to issues including restricted access, proprietary formats, incomplete metadata, and inconsistent processing procedures. Of those available, common issues include compass drift, instrument movement, positional uncertainty, incomplete bin coverage, and inconsistent or missing metadata. Where ancillary data such as heading, pitch, and roll are retained, many errors can be identified and corrected. By combining a regional hydrodynamic model with ADCP data, the benefit of a measurement–model feedback loop is demonstrated: models help identify measurement inconsistencies, guide corrections, and inform deployment planning, while observations remain essential for calibration. Modelling results show that positional error in the ADCP location can introduce uncertainties that far exceed allowable modelling thresholds. Data quality depends as much on workflow and archival as on instrument performance, and improved centralised processed products tailored to different applications would significantly improve usability, reproducibility, and cross-site comparability.