<p>The rate of reduction of Arctic Ocean sea ice cover and its change is an important key issue in the study of global climate change. Wave climate variability and the wave effects in the Arctic Ocean plays important roles in influencing the rate of sea ice melting. Aiming to improve the parameterization of wave numerical model that considers the presence of sea ice in polar region and to develop the associated satellite remote sensing technologies, in situ wave observations at the sea-ice edge and Marginal Ice Zones are essential. Currently the data and observations are scarce.</p> <p>This study developed a low-cost miniature wave drifting buoy, its shape is 50 cm diameter dish, built-in IMU, Iridium satellite modem and temperature and salinity sensor, etc., to monitor the wave height, period, direction and wave spectral shape, sea surface Mean Square Slope (MSS), surface ocean temperature (SST) and GPS positioning.</p> <p>The signal sampling frequency is 10Hz, the spectral analysis is carried out on-board using ARM single chip computer in the buoy. The data is then encoded to Iridium satellite in real-time. In this study, in August 2021 and 2022, 8 and 10 sets of miniature buoys were deployed in Fram Strait off the western Svalbard Islands, respectively. The buoys were deployed in cluster and placed 15 km apart from each other, forming a rectangular spatial array, and drifting with West Spitzbergen Current, transported northward into the ice edge area of Svalbard northwest sea.</p> <p>The observation took place every two hours for about three months. This report presents the time series of the observation data. First, we analyzed the drift trajectories of the buoy cluster, estimated the sea surface dispersion coefficient, Lyapunov index from the spatial array shape change rate of the buoy cluster. Secondly, sea surface temperature variation along the meridional trajectories was investigated. The results showed that the surface water mass was converged around Molloy Abyss, and the surrounding water body was accompanied by rapid temperature drop. On the other hand, in the wave analysis of the MIZ, the SAR images were used to identify the sea ice edge and ice concentration and to investigate the attenuation of wave spectral shape between the sea ice zone and the open ice-free waters in the vicinity.</p>
Real-time, continuous, and long-term marine monitoring data benefits ocean research. This study developed a low-cost, multi-parameter, miniature wave buoy. High spatial and temporal resolution of sea surface parameters, including wind, waves, and current, can be obtained at low cost through the deployment of numerous buoys, thus forming an observation array. Tested in the laboratory water tank, the relative error of water surface slope measurement of the buoy was approximately 5.6% when the slope angle was less than 15°. For frequencies between 0.1 and 1.0 Hz, the measurement of slope spectrum was almost identical to that of the wave gauge. The buoy underestimated the slope spectrum between 1.0–1.56 Hz. A good relationship (r2 = 0.75) was obtained between wind speed at 10 m above sea surface (U10) and the low-pass-filtered mean square slope (LPMSS). After incorporating the wave age into the U10 inversion process, the root mean square error (RMSE) and BIAS were reduced to 1.15 m/s and 0.02 m/s, respectively. The 2D distribution of buoy-measured slope components was used to detect the wind direction, with an RMSE of 23.7°. The spectral tail slope steepened with increasing wind speed at low wind speeds (<7 m/s). A technical flow chart of the miniature wave buoy is proposed to observe the sea surface parameters. This miniature buoy will play an essential complementary role in the growing demand for sea state monitoring, especially in nearshore oceans.
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