Seaguardii DCP: innovation in doppler current profiling and observatory technology

Peer Reviewe

Seaguardii DCP: innovation in doppler current profiling and observatory technology

Peer Reviewe

SailBuoy Ocean Currents: Low-Cost Upper-Layer Ocean Current Measurements.

This study introduces an alternative to the existing methods for measuring ocean currents based on a recently developed technology. The SailBuoy is an unmanned surface vehicle powered by wind and solar panels that can navigate autonomously to predefined waypoints and record velocity profiles using an integrated downward-looking acoustic Doppler current profiler (ADCP). Data collected on two validation campaigns show a satisfactory correlation between the SailBuoy current records and traditional observation techniques such as bottom-mounted and moored current profilers and moored single-point current meter. While the highest correlations were found in tidal signals, strong current, and calm weather conditions, low current speeds and varying high wave and wind conditions reduced correlation considerably. Filtering out some events with the high sea surface roughness associated with high wind and wave conditions may increase the SailBuoy ADCP listening quality and lead to better correlations. Not yet resolved is a systematic offset between the measurements obtained by the SailBuoy and the reference instruments of ±0.03 m/s. Possible reasons are discussed to be the differences between instruments (various products) as well as changes in background noise levels due to environmental conditions

Directional wave measurements from navigational buoys

In-situ wave measurements are often required by marine industry standards and for verification of coastal wave forecasts. Obtaining wave measurements is costly and it would be advantageous to utilize existing platforms like navigational buoys designed for environmental monitoring. In this study, a wave sensor module (MOTUS Wave Sensor, Aanderaa Data Instruments) installed on a navigational buoy (Tideland) and a coastal buoy (EMM2.0) is validated against a dedicated wave measurement buoy (Waverider, Datawell). The validation is based upon four months of measurements off the west coast of Norway. The results show that the MOTUS sensor on-board navigational/coastal buoys provide accurate measurements of wave parameters compared to Waverider. Wave height biases were less than 0.04 m over the full wave spectra, and less than 5% for frequencies between 0.05 and 0.45 Hz (0.01 Hz bin width). Mean wave direction bias for the full spectra was 1.4 and 2.8 degrees, and less than 5 and 10 degrees in frequency bins between 0.05 and 0.45 Hz for the navigational and coastal buoy, respectively. External compass measurements were required for accurate directional measurements for the coastal buoy. The validated wave sensor provides in-situ directional wave measurements with measurement uncertainties well within recommended accuracy levels.publishedVersio