The relationship between significant wave height ($H_{1/3}$) and period ($T_{1/3}$) was obtained using wave data from the East and Yellow coasts of the Korean Peninsula to facilitate the calculations of the wave parameters. In addition, the JONSWAP spectral parameters were estimated and analyzed for all wave height ranges. The relational expression between the two wave variables ($H_{1/3}$~$T_{1/3}$) obtained from this study showed a significant difference from the previously proposed relational expressions, most of which tended to follow the lower limit of the data. Meanwhile, the suggested peak enhancement factor (PEF,$\mathsf{\gamma }$) is 1–7; however, for this study, a peak control factor (PCF,${\mathsf{\gamma }}_c$) with a range of 0–10 was introduced. As a result of the analysis, the PCF was determined to be 1.13–1.42, which is approximately 40% smaller than the previously proposed $\mathsf{\gamma } = 3.3$. The probability density distribution of the appropriate PCF was then calculated, and the gamma and log-normal distributions for the East and Yellow coasts of the Korean Peninsula were found, respectively. This study covered waves of all range heights, and the analysis results can be used as important data to explain the characteristics of the sea area.

The tailings that remain after the collection and screening of Mn nodules are directly discharged into the ocean and are anticipated to influence the ocean environment and marine organisms. The primary factors determining the influence (diffusion) range are the ocean currents and the settling velocity of the tailings; the latter is directly correlated with the time that the tailings remain in the water column. Flocculation is affected by the actual tailing discharge conditions. The settling velocity of the tailings is expected to increase as a result of flocculation; therefore, data on the size distribution of flocs are needed to compute the settling velocity of the tailings. In this study, a method for estimating the floc size distribution of the tailings is proposed, and the general flocculation process is analyzed using the apparent settling velocity, which is readily estimated by simple settling experiments conducted with standard tailings at different concentrations. The apparent falling time-curve followed a power function, and the flocculated grain size was 3–4 times larger than that before flocculation. In addition, flocculation and falling were significantly inhibited by the time required for flocculation. The method suggested in this study was validated by using a numerical particle-tracking model based on the autoencoder concept, which estimates the apparent settling velocity using the flocculated grain size distribution. The computed time-velocity curve agreed well with the apparent time curve obtained in the experiment, with an error of approximately 5–10% except in the initial time range (0–30 s), despite the qualitative nature of the assumptions.

Harmful algal blooms (HABs) are types of phytoplankton overgrowth that adversely affect marine ecosystems and aquaculture resources. One such HAB species, Cochlodinium polykrikoides, occurs irregularly and causes significant damage to the aquaculture industry along the coastal regions of Korea. In this study, we developed and implemented an integrated system to detect and predict HAB occurrences in real time. This system comprises four main components: (1) a real-time detection system utilizing acoustic sensing, ocean weather, water temperature, salinity, and chlorophyll, satellite images, genetic analysis, and optics; (2) a prediction model system based on current and tidal, HAB occurrence, and HAB movement and diffusion models; (3) an additional data based on HAB information of sampling data and HAB information of GPS data, and (4) an integrated information system utilizing data storage servers and a visualization platform. We applied and assessed the efficiency of this integrated system in the South Sea of Korea from 2017 to 2019. Particularly, HABs occurred significantly in 2019, and the system demonstrated the feasibility of detection and prediction under field conditions. Implementing a more advanced integrated detection and prediction system in the field is anticipated to minimize the damage caused by irregular HAB occurrences every year.

Nutrient data obtained from field observations have the potential to enhance our understanding of oceanic biogeochemical cycling and productivity changes. In particular, long-term nutrient data can provide valuable information on the links between climate change and biogeochemical changes. However, unlike other observational variables such as sea surface temperature, nutrient data are limited in terms of their broad-scale observations and automated sensor-based measurements. In this study, we analyzed nitrate and phosphate data obtained from coastal regions in Northeast Asia and the northwest Pacific from 1980 to 2019 using the spatiotemporal kriging technique and provide results in a spatiotemporal grid format. The data are available at monthly intervals and may be attractive to researchers in the fields of oceanography, marine ecology, and marine biogeochemistry at the climate change scale. Furthermore, sharing the source code of the data production process can contribute to better long-term data reproduction in the future.