• Article

    Estimation of Extreme Wind Speeds in the Western North Pacific Using Reanalysis Data Synthesized with Empirical Typhoon Vortex Model

    모조 태풍 합성 재분석 바람장을 이용한 북서태평양 극치 해상풍 추정

    Hye-In Kim and Il-Ju Moon

    김혜인, 문일주

    In this study, extreme wind speeds in the Western North Pacific (WNP) were estimated using reanalysis wind fields synthesized with an empirical ... + READ MORE
    In this study, extreme wind speeds in the Western North Pacific (WNP) were estimated using reanalysis wind fields synthesized with an empirical typhoon vortex model. Reanalysis wind data used is the Fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5) data, which was deemed to be the most suitable for extreme value analysis in this study. The empirical typhoon vortex model used has the advantage of being able to realistically reproduce the asymmetric winds of a typhoon by using the gale/storm-forced wind radii information in the 4 quadrants of a typhoon. Using a total of 39 years of the synthesized reanalysis wind fields in the WNP, extreme value analysis is applied to the General Pareto Distribution (GPD) model based on the Peak-Over-Threshold (POT) method, which can be used effectively in case of insufficient data. The results showed that the extreme analysis using the synthesized wind data significantly improved the tendency to underestimate the extreme wind speeds compared to using only reanalysis wind data. Considering the difficulty of obtaining long-term observational wind data at sea, the result of the synthesized wind field and extreme value analysis developed in this study can be used as basic data for the design of offshore structures. - COLLAPSE
    March 2021
  • Article

    Correlation Analysis Between the Variation of Net Surface Heat Flux Around the East Asian Seas and the Air Temperature and Precipitation Over the Korean Peninsula

    동아시아 해역의 표층 순열속 변동과 한반도 기온 및 강수량 변동의 상관성 분석

    Seok-Joon Lee and You-Soon Chang

    이석준, 장유순

    In this study, using 16 ORA-IP (Ocean Reanalysis Intercomparison Project) data, we investigated spatial and temporal changes of net surface heat flux ... + READ MORE
    In this study, using 16 ORA-IP (Ocean Reanalysis Intercomparison Project) data, we investigated spatial and temporal changes of net surface heat flux in the East Asian seas and presented a new ensemble net surface heat flux index. The ensemble net surface heat flux index is produced considering the data distribution and the standard deviation of each ORA-IP. From the correlation analysis with air temperature averaged over the Korean Peninsula, ensemble net heat flux around the Korea Strait shows the highest correlation (0.731) with a 3 month time lag. For the correlation study regarding precipitation over the Korean Peninsula, it also shows significant correlation especially in winter and spring seasons. Similar results are also found in comparison with climate indices (AO, PDO, and NINO3.4), but ensemble net surface heat flux data in winter season reveals the strongest correlation patterns especially with winter temperature and spring precipitation. - COLLAPSE
    March 2021
  • Article

    Weekly Variation of Prokaryotic Growth and Diversity in the Inner Bay of Yeong-do, Busan

    부산 영도 내만에서 원핵생물 성장 및 다양성의 주간 변동 특성

    Wonseok Yang, Jae Hoon Noh, Howon Lee, Yeonjung Lee, and Dong Han Choi

    양원석, 노재훈, 이호원, 이연정, 최동한

    To understand the temporal variation of prokaryotic communities in a temperate coastal area, prokaryotic abundance, activity, and community composition were investigated every ... + READ MORE
    To understand the temporal variation of prokaryotic communities in a temperate coastal area, prokaryotic abundance, activity, and community composition were investigated every week for over a year at a coastal monitoring station of Yeong-do, Busan. The prokaryotic abundances fluctuated about 10 times, ranging from 2.0 to 20.1 × 105 cells mL-1 and tended to be high in spring when phytoplankton bloom occurred. The prokaryotic thymidine incorporation rates (TTI) varied in a low range between 0.2 and 11.5 pmol L-1 h-1 in winter. However, in summer, TTI were increased up to a range of 8.3 to 17.4 pmol L-1 h-1, showing an increasing pattern in summer. During the study period, Alphaproteobacteria was the most dominant class for most of the year, followed by Flavobacteria. While the seasonal variation of prokaryotic composition was not apparent at the class level, many prokaryotic species showed a distinct temporal or seasonal variation for the year. In the coastal site, prokaryotic biomass and activity did not show significant correlations with temperature and chlorophyll-a, which are well known to regulate prokaryotic growth in marine environments, suggesting that the study area may be affected by diverse sources of organic matter for their growth. - COLLAPSE
    March 2021
  • Note

    Comparison of Morphological Analysis and DNA Metabarcoding of Crustacean Mesozooplankton in the Yellow Sea

    황해 갑각 중형동물플랑크톤의 형태 분석과 DNA 메타바코딩 비교

    Garam Kim, Hyung-Ku Kang, Choong-Gon Kim, Jae Ho Choi, and Sung Kim

    김가람, 강형구, 김충곤, 최재호, 김성

    Studies on marine zooplankton diversity and ecology are important for understanding marine ecosystem, as well as environmental conservation and fisheries management. DNA ... + READ MORE
    Studies on marine zooplankton diversity and ecology are important for understanding marine ecosystem, as well as environmental conservation and fisheries management. DNA metabarcoding is known as a useful tool to reveal and understand diversity among animals, but a comparative evaluation with classical microscopy is still required in order to properly use it for marine zooplankton research. This study compared crustacean mesozooplankton taxa revealed by morphological analysis and metabarcoding of the cytochrome oxidase I (COI). A total of 17 crustacean species were identified by morphological analysis, and 18 species by metabarcoding. Copepods made up the highest proportion of taxa, accounting for more than 50% of the total number of species delineated by both methods. Cladocerans were not found by morphological analysis, whereas amphipods and mysids were not detected by metabarcoding. Unlike morphological analysis, metabarcoding was able to identify decapods down to the species level. There were some discrepancies in copepod species, which could be due to a lack of genetic database, or biases during DNA extraction, amplification, pooling and bioinformatics. Morphological analysis will be useful for ecological studies as it can classify and quantify the life history stages of marine zooplankton that metabarcoding cannot detect. Metabarcoding can be a powerful tool for determining marine zooplankton diversity, if its methods or database are further supplemented. - COLLAPSE
    March 2021