Near-real Time Monitoring of Coastal Lagoon Turbidity Distribution Using Modis Data

We have been studying the turbidity estimation for Lakes Shinji and Nakaumi, Shimane Prefecture Japan using satellite sensors. Recently, we have developed a turbidity monitoring system for this area using near-real-time MODIS 250-m resolution band reflectance data which have been provided from Japan Aerospace Exploration Agency (JAXA). MODIS sensors on-board the Terra and Aqua satellites visit this area almost once or twice a day, so the limitation of sparse visit is solved to some extent (the limitation of cloud cover still remains). Since thin cloud and occasionally sand storm cover the ocean and/or lake areas, some threshold techniques are applied to remove the data or to issue warning flags. Empirical formulas adjusted for each lake (Lakes Shinji and Nakaumi) are used to estimate the turbidity from the Band 1 reflectance. The resulting turbidity distribution map is now published on our web site for general users. In this presentation, an outline of this system will be introduced.