적조 원격탐사 활용을 위한 적조생물 종 고유광특성 연구

Abstract

적조 종에 따라 해색이 다르다는 점에 착안해 해색 모델로부터 적조 종을 역 추정하는 기술을 개발하는데 있어 기본 입력 변수가 되는 적조 생물에 관한 광학적 특성(흡수, 역산란 특성)을 연구하였다. 실험실 수준에서의 적조 생물의 광특성을 조사하기 위해서 남해에서 채취 된 21종의 적조 생물을 배양하고 pectrophotometer를 이용해 광합성 색소에 의한 흡수계수(absorption coefficient, a)와 역산란계수(backscattering coefficient, bb)를 측정하였다. 또한 spectrophotometer를 이용해 측정 된 흡수 및 역산란 계수와 클로로필 농도를 이용하여 비 흡광계수(a*)와 비 역산란계수(bb*)를 계산하였으며 이들 스펙트럼의 모양과 값을 비교하였다. 적조 생물 종에 따른 a*은 파장대 440nm에서 0.005 - 0.06 m2/mg의 값을 가지며, bb*의 범위는 10-2~10-4 m2/mg로 종간 약 100배의 차이가 있었다. 이와 같이 적조생물 종에 따라 스펙트럼의 모양이 다르게 나타나 해색 스펙트럼으로 종의 식별이 가능하였다. 이 결과는 적조 원격탐사기술 활용을 위한 기초 자료로 이용가능하며 해색모델 개발의 입력변수로 활용될 수 있다.

Red tide occurs every year in coastal area. Its spatial-temporal scale is getting larger and days of duration is getting longer than ever. Therefore, the economical loss of aquaculture is increasing each year. Red tide algae are estimated 150 different species all around the world, among these, 40 species are appeared in Korean coastal sea and danoflagellate is the main species which causes red tide. Remote sensing technology is conducted to detect red tide but it is still in sufficient. Firstly, spatial resolution of ocean color satellite is 1km, as this reason, it can only detect large scale of red tide. Secondly, coastal area, which occurs red tide, is often area with high density of suspended particulate. Therefore it is difficult to recognize between red tide and suspended particles. Recently, ocean color depends on the species of red tide and it discovers that ocean color is different with different types of algae. For the research of optical properties of red tide algae, phytoplankton was cultivated, measured the absorption and backscattering coefficient properties. Based on this, differences of optical properties between red tide algae are researched. Optical property differences based on the red tide species are gained from the shape and value of spectrum. Main absorption band was 430 - 440 nm and 680 nm and accessory absorption band was shown according to other red tide species. Absorption spectrums according to species are appeared diversely from 0.005 to 0.06 m2/mg. The range of specific backscattering coefficient was 10-2~10-4 m2/mg, it showed 100 times differences according to the different species of red tide algae and spectrum shape was also quite different. It is estimated that accessory absorption band, absorption difference in the same band, backscattering spectrum shape strength difference will be the main factor for classifying the red tide species. For more accurate remote sensing detect for red tide, optical character gained from red tide algae species are needed to store as data base, and also inverse model should be developed to analyze the species and amount of red tide from ocean color.