https://repository.kopri.re.kr/handle/201206/5517 2026-04-19T16:20:54Z 2026-04-19T16:20:54Z Kim, Hyun-cheol Lee, Tongsup Yoon, Joo-Eun Kim, Ju-Hyoung Park, Ki-Tae Alison M. Macdonald Kim, Il-Nam https://repository.kopri.re.kr/handle/201206/5620 2022-03-24T07:11:50Z 2017-01-01T00:00:00Z

Title: Estimating Remineralized Phosphate and Its Remineralization Rate in the Northern East China Sea During Summer 1997: A Snapshot Study Before Three-Gorges Dam Construction Authors: Kim, Hyun-cheol; Lee, Tongsup; Yoon, Joo-Eun; Kim, Ju-Hyoung; Park, Ki-Tae; Alison M. Macdonald; Kim, Il-Nam Abstract: The northern East China Sea (a.k.a., "The South Sea") is a dynamic zone in which there have been a variety of effects on the marine ecosystem due to the construction of the Three-Gorges Dam. As the northern East China Sea region is vulnerable to climate forcing and anthropogenic impacts it is important to investigate how the remineralization rate in the northern East China Sea has changed in response to such external forcing. To obtain a baseline for future comparison, we use an historical hydrographic dataset from August 1997. We estimate the amount of remineralized phosphate by decomposing the effects of physical mixing and biogeochemical processes from measurements (temperature, salinity, and phosphate) of the water column. The estimated column inventory of remineralized phosphate ranged from 0.8 to 42.4 mmol P m-2 (mean value of 15.2 ± 12.0 mmol P m-2). Our results suggest that the Tsushima Warm Current was a strong contributor to primary production during the summer 1997 in the study area. The estimated summer (June？August) remineralization rate in the region before construction of the Three-Gorges Dam was 18 ± 14 mmol C m-2 d-1.

2017-01-01T00:00:00Z Jo, Young-Heon Dohoon Kim Seunghyun Son Kim, Hyun-cheol https://repository.kopri.re.kr/handle/201206/5717 2022-03-24T07:12:44Z 2016-01-01T00:00:00Z

Title: Analysis of the timing of phase changes in the chlorophyll concentration in the East/Japan Sea Authors: Jo, Young-Heon; Dohoon Kim; Seunghyun Son; Kim, Hyun-cheol Abstract: Geographically heterogeneous linear and non-linear chlorophyll-a (CHL) trends in the East Sea/Japan Sea (EJS) region were analyzed based on monthly mean Moderate Resolution Imaging Spectroradiometer (MODIS) CHL data from January 2003 to December 2012. The non-linear trends were derived from the residuals of decomposed CHL time series using ensemble empirical mode decomposition (EEMD). To understand the general spatial and temporal variability of the non-linear CHL trends, a complex empirical orthogonal function (CEOF) was employed. The first two CEOF modes indicate that an upward CHL trend occurred in 2007 with 95.6% variance, whereas a downward CHL trend occurred in 2009 with 4.1% variance. Furthermore, the specific timing of the phase changes in CHL was calculated based on upward or downward non-linear trends of CHL for six major regions of interests. To examine the dominant forces in phase changes in CHL, the Multivariate El Nino-Southern Oscillation (ENSO) Index (MEI) was used. We determined that the local turning patterns of CHL over the last ten years were closely related to changes in ENSO events, which were also associated with changes in the total amount of fish catches off the east coast of the Korean Peninsula. These results also suggest that the short-term total amount of fish catches may be predictable based on the remotely sensed non-linear CHL observations.

2016-01-01T00:00:00Z Park, Jeong-Won Lee, Sang-Hwan Park, Kyungseok Kim, Hyun-cheol https://repository.kopri.re.kr/handle/201206/5917 2022-03-24T07:12:13Z 2015-01-01T00:00:00Z

Title: A Study on Extending Successive Observation Coverage of MODIS Ocean Color Product Authors: Park, Jeong-Won; Lee, Sang-Hwan; Park, Kyungseok; Kim, Hyun-cheol Abstract: In the processing of ocean color remote sensing data, spatio-temporal binning is crucial for securing effective observation area. The validity determination for given source data refers to the information in Level-2 flag. For minimizing the stray light contamination, NASA OBPG's standard algorithm suggests the use of large filtering window but it results in the loss of effective observation area. This study is aimed for quality improvement of ocean color remote sensing data by recovering/extending the portion of effective observation area. We analyzed the difference between MODIS/Aqua standard and modified product in terms of chlorophyll-a concentration, spatial and temporal coverage. The recovery fractions in Level-2 swath product, Level-3 daily composite product, 8-day composite product, and monthly composite product were 13.2(±5.2)%, 30.8(±16.3)%, 15.8(±9.2)%, and 6.0(±5.6)%, respectively. The mean difference between chlorophyll-a concentrations of two products was only 0.012%, which is smaller than the nominal precision of the geophysical parameter estimation. Increase in areal coverage also results in the increase in temporal density of multi-temporal dataset, and this processing gain was most effective in 8-day composite data. The proposed method can contribute for the quality enhancement of ocean color remote sensing data by improving not only the data productivity but also statistical stability from increased number of samples.

2015-01-01T00:00:00Z Kim, Hyun-cheol https://repository.kopri.re.kr/handle/201206/8897 2022-03-24T07:12:59Z 2015-01-01T00:00:00Z

Title: A study Oceanic Environmental Change using Ocean Color Remote Sensing Data Authors: Kim, Hyun-cheol

2015-01-01T00:00:00Z