Variations in phytoplankton concentrations result from changes of the ocean color caused by phytoplankton pigments. Thus, ocean spectral reflectance for low chlorophyll waters are blue and high chlorophyll waters tend to have green reflectance. In the Korea region, clear waters and the open sea in the Kuroshio regions of the East China Sea have low chlorophyll. As one moves even closer to the northwestern part of the East China Sea, the situation becomes much more optically complicated, with contributions not only from higher concentrations of phytoplankton, but also from sediments and dissolved materials from terrestrial and sea bottom sources. The color often approaches yellow-brown in the turbidity waters (Case Ⅱ waters). To verify satellite ocean color retrievals, or to develop new algorithms for complex case Ⅱ regions requires ship-based studies. In this study, we compared the chlorophyll retrievals from NASA's SeaWiFS sensor with chlorophyll values determined with standard fluorometric methods during two cruises on Korean NFRDI ships. For the SeaWiFS data, we used the standard NASA SeaWiFS algorithm to estimate the chlorophyll a distribution around the Korean waters using Orbview/ SeaWiFS satellite data acquired by our HPRT station at NFRDI. We studied to find out the relationship between the measured chlorophyll a from the ship and the estimated chlorophyll a from the SeaWiFS satellite data around the northern part of the East China Sea, in February, and May, 2000. The relationship between the measured chlorophyll_a and the SeaWiFS chlorophyll_a shows following the equations (1) in the northern part of the East China Sea.
Chlorophyll_a=0.121Ln(X) + 0.504, R2 = 0.73 (1)
We also determined total suspended sediment mass (SS) and compared it with SeaWiFS spectral band ratio. A suspended solid algorithm was composed of in-situ data and the ratio (LWN(490 nm)/LWN(555 nm)) of the SeaWiFS wavelength bands. The relationship between the measured suspended solid and the SeaWiFS band ratio shows following the equation (2) in the northern part of the East China Sea.
SS=-0.703 Ln(X) + 2.237, R2 = 0.62 (2)
In the near future, NFRDI will develop algorithms for quantifying the ocean color properties around the Korean waters, with the data from regular ocean observations using its own research vessels and from three satellites, KOMPSAT/OSMI, Terra/MODIS and Orbview/SeaWiFS.
Satellite data, with sea surface temperature(SST) by NOAA and sea level(SL) by Topex/poseidon, are used to estimate characteristics on the variations and correlations of SST and SL in the East Asian Seas from January 1993 through May 1998. We found that there are two climatic characteristics in the East Asian seas: the oceanic climate, the eastern sea of Japan, and the continental climate, the eastern sea of China, respectively. In the oceanic climate, the variations of SL have the high values in the main current of Kuroshio and the variations of SST have not the remarkable seasonal variations because of the continuos compensation of warm current by Kuroshio. In the continental climate, SL has high variations in the estuaries(the Yellow River, the Yangtze River) with the mixing the fresh water and the saline water in the coasts of continent and SST has highly the seasonal variations due to the climatic effect of continents. In the steric variations of summer, the eastern sea of Japan, the East China Sea and the western sea of Korea is increased the sea level about 10∼20㎝. But the Bohai bay in China have relatively the high values about 20∼30㎝ due to the continental climate. Generally the trends of SST and SL increased during all periods. That is say, the slopes of SST and SL is presented 0.29℃/year and 0.84㎝/year, respectively. The annual and semi-annual amplitudes have a remarkable variations in the western sea of Korea and the eastern sea of Japan. In the case of the annual peaks, there appeared mainly in the western sea of Korea and the eastern sea of Japan because of the remarkable variations of SL associated with Kuroshio. But in the case of the semi-annual peaks, there appeared in the eastern sea of Japan by the influence of current, and in the western sea of Korea by the influence of seasonal temperature, respectively. From our results, it should be believed that SST and SL gradually increase in the East Asian seas concerning to the global warming. So that, it should be requested to the international co-operation against to the change of the abnormal climate.
침식률 측정장치인 SEDFLYME을 사용하여 직접 측정한 침식률 자료를 이용하는 퇴적물 수송에 관한 2차원 모형이 개발되었다. 개발된 모형은 현장 적용성을 높이기 위하여 경계밀착좌표계를 수평방향에 대해 사용하며, 퇴적물 이동 모의시 침식률 산정에서 불확실성을 줄이기 위해 침식률 측정자료를 직접 사용한다. 개발된 모형은 부유사와 소유사 이동을 모두 고려한다. 모형의 정확성을 검토하기 위하여 1차원 수로에서 장갑화 현상을 모의하고 실험자료와 비교하였다. 비
실험 또는 계측에 의해 관측된 관측치들은 종종 어떤 기준치 이하의 작은 값들이 기록되는데, 이들 기준치 이하의 값들이 크기는 미소할지라도 평균이나 분산 추정시 왜곡된 결과를 줄 수 있다. 그러나 우리 나라에서는 관측오차로 간주하여 N.D.(Not Detected)로 처리하는 것을 관례로 하고 있어 미소치들이 기록되지 않고 있다. EK라서 본 연구에서는 부여 취수장의 암모니아성 질소(NH-N)자료가 크기에 따라 분표형이 다름을 조사하고 그 분포를 구별할
본 연구에서는 한강유역의 1일, 2일, 3일 연최대강우자료를 대상으로 L-모멘트법을 이용한 지점 빈도해석과 지역 빈도해석을 실시하여 그 결과를 비교하였다. 지역빈도해석을 실시하기 위하여 한강유역을 남한강, 북한강, 한강하류부 유역의 3개 소유역으로 분할하고, 각 유역에 대한 자료의 이산도 및 동질성을 검토하였으며, 각 소유역에 대하여 여러 분포형을 적용한 결과, 남한강유역과 한강하류부 유역은 lognormal 분포형, 북한강 유역은 gamma-3 분포형