Cal/Val of ocean color algorithms in Korean Waters

Abstract

Our research in the past years has shown that the bio-optical properties of most Korean coastal waters belong to Case 2. Even the Korean coastal waters of the East/Japan Sea deviate from Case 1, not to mention the Yellow Sea. Probably only the Tsushima Warm Current region in the East China Sea would belong to Case 1. Thus the major standard ocean color products, i.e., chlorophyll concentration by empirical Case 1 algorithm, are not accurate in most Korean coastal waters, although they still might carry useful qualitative information. Their utility has not met our expectations yet.In coming years, there will be more ocean color data available than can be utilized. In spite of unprecedented wealth of data, utility of ocean color data in coastal waters will be severely limited by lack of operational algorithms for some time. By “operational algorithms”, I mean algorithms that are reasonably validated and can be used on a routine basis with certain degree of reliability in accuracy. To have operational ocean color algorithms in Korean waters, we are in want of good-quality datasets of fundamental variables and parameters: 1) Quality control of measurement. Protocols of measuring fundamental variables, such as suspended sediments, should be established. It seems difficult to compare or use the suspended sediments data from various researchers, most of which are poorly quality-controlled. Another example is chlorophyll concentration. We found acidification-fluorometric method underestimates HPLC chlorophyll values up to 50% in the Ulleung Basin, East/Japan Sea. 2) Good datasets of fundamental parameters. Simulation of reflectance showed that reflectance values are most sensitive to the absorption and backscattering coefficient of suspended sediments in the case of the Yellow Sea. However, there are few such data of good quality in the Yellow Sea. Such data are required for proper parameterization and calibration of algorithms. When I quality