Laguna : 汽水域研究

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Laguna : 汽水域研究 14
2007-12 発行

MODIS による宍道湖・中海の濁度分布推定

Estimation of Turbidity in Lakes Shinji and Nakaumi from MODIS
山本 周一郎
古津 年章
野々原 伸吾
作野 裕司
MODIS is a medium-resolution satellite imaging sensor that has a observation interval of once or twice a day, although the spatial resolution is marginal(250 m). Because of the high observation frequency, it should be suitable for operational monitoring of water quality of Lakes Shinji and Nakaumi. A preliminary study was undertaken to test the utility of MODIS channels 1 and 2(red and near-IR bands)for turbidity mapping. Two test data sets, May 2 2002 and August 23 2003, are used for this study. Data from a high spatial resolution satellite sensor ASTER are also used for comparison. For May 2 2002, turbidity is thought to be dominated by inorganic materials and MODIS Band 1(red)appears to produce a reasonable turbidity map. On the other hand, on August 23 2003, both organic and inorganic materials contributed to total turbidity. This caused signifi cant differences in turbidity maps created from MODIS Band 1, MODIS Band 2, and ASTER Band 1(green). Therefore we suggest that combined use of MODIS Bands 1 and 2 may produce more reliable turbidity estimates. Further information may be available from MODIS Band 4(green)although this channel has a coarser resolution of 500 m.