우리나라 연안의 동․하계 검조위와 유속 관측자료의 상관성 연구

Abstract

This paper aims to examine the correlation between tidal levels and field observation current velocity during the winter and summer seasons off the coast of Korea. The data used in the study are current velocity data collected and obtained by the researcher from 2019 to 2023 (a total of 5 years) in the summer and winter seasons at a total of 28 points in the East Sea, South Sea, and West Seas, as well as 20 tidal level data located near the field observation peak among the tidal stations of the Korea Hydrographic and Oceanographic Agency(KHOA). Through this, the correlation between the tidal level and the water current of the entire coast of Korea, which is proposed in this study, makes it possible to estimate the approximate current velocity of the target sea area using the tidal level data provided by Korea Hydrographic and Oceanographic Agency(KHOA), even if the tidal current field observation is not carried out, which requires a lot of time and cost. This can be provided as basic data for researchers and marine engineering designers when researching the marine environment. The detailed findings obtained from this study are summarized as follows. (1) As a result of analyzing the observed current velocity off the coast of Korea, it was found that the maximum current velocity ranges from 21.95 cm/s in the bottom layer of Yeongdeok (2023.01) to 195.41 cm/s in the surface layer of Boryeong (2022.08) and from 5.55 cm/s in the bottom layer of Yeongdeok (2023.01) to 54.68 cm/s in the surface layer of Boryeong (2022.08) in the case of mean current velocity. In general, the observed current was weak on the East Sea, where the tidal level is small, and strong on the West Sea, where the tidal level is large. (2) According to the tidal level data and analysis results of the tidal station, both the Spring range and the Mean sea level showed a tendency to increase in the order of East Sea≤ South Sea < West Sea. Analysis of the tide form factor showed that the tidal pattern was mixed tide with a predominance of diurnal tide in Hupo in East Sea, and semidiurnal tide predominantly in the entire sea area of East Sea except Hupo, Wando in the South Sea, Mokpo and Heuksando in the West Sea. In other areas, tidal patterns in the form of semidiurnal tides were exhibited. (3) As a result of analyzing the correlation between tidal level and observed current velocity, both spring tide and mean sea level showed a larger coefficient of determination when analyzed with mean velocity than maximum current velocity. In addition, compared to the surface, which is relatively affected by external factors such as wind, the tidal form factor was found to be larger at the bottom. Seasonally, the value was greater in winter than in summer. In addition, in the analysis of the correlation between the tidal level and the tidal current harmonic constant, the coefficient of determination was not significantly different from that of the tidal level and the observed current velocity. (4) As a result of determining the correlation between tidal level and observed current velocity by sea area and season, the correlation equation was y=0.0448x+0.1472 and the coefficient of determination was 0.3843 for mean sea level and mean current velocity on the sea surface during the entire observation period. In addition, in the case of bottom, the correlation equation was y=0.0472x+0.0998, and the coefficient of determination was 0.4775, which showed a relatively large value. The largest coefficient of determination was the relationship between the spring tide and the mean velocity, with a correlation of y=0.0287x+0.0896 and a coefficient of determination of 0.5503.