Satellite ocean color observation with 250 m spatial resolution using ADEOS-II GLI

摘要

Ocean color products (aerosol, normalized water-leaving radiance, and chlorophyll-a concentration) were produced using 250-m resolution data (center wavelengths at 462, 543, 661, 824, 1645, and 2194nm) of Global Imager (GLI) on ADEOS-II by GLI standard ocean atmospheric correction algorithms (i.e., basically same as the 1-km algorithm). The 250-m ocean color products can show finer spatial structures than standard 1km products, but we found some problems; (a) there is large noise because GLI 250-m channels were designed originally for bright area (land vegetation), (b) we have to use channels which are not optimized for the atmospheric correction (wide bandwidth, large noise, and including slight water-vapor absorption), and (c) we need more consideration about cloud shadow, sea-surface reflectance (sunglint and white cap), and shallow bottom. Sea surface reflectance has fine spatial structures in the actual ocean due to fine structure of surface winds influenced by the coastal topography, and we often cannot distinguish the surface reflection from aerosol scattering above the sea surface. JAXA is planning a new mission, "Second generation GLI (SGLI) on GCOM satellites", which has visible and near-infrared channels with 250-m spatial resolution improving noise level and bandwidth applicable to the coastal ocean-color observations.