Classification of Case-Ⅱ waters using Hyperspectral (HICO) Data over North Indian Ocean

摘要

State of the art Ocean color algorithms are proven for retrieving the ocean constituents (chlorophyll-a, CDOM and Suspended Sediments) in case-Ⅰ waters. However, these algorithms could not perform well at case-Ⅱ waters because of the optical complexity. Hyperspectral data is found to be promising to classify the case-Ⅱ waters. The aim of this study is to propose the spectral bands for future Ocean color sensors to classify the case-Ⅱ waters. Study has been performed with Rrs's of HICO at estuaries of the river Indus and GBM of North Indian Ocean. Appropriate field samples are not available to validate and propose empirical models to retrieve concentrations. The sensor HICO is not currently operational to plan validation exercise. Aqua MODIS data at case-Ⅰ and Case-Ⅱ waters are used as complementary to in-situ. Analysis of Spectral reflectance curves suggests the band ratios of Rrs 484 nm and Rrs 581 nm, Rrs 490 nm and Rrs 426 nm to classify the Chlorophyll -a and CDOM respectively. Rrs 610 nm gives the best scope for suspended sediment retrieval. The work suggests the need for ocean color sensors with central wavelength's of 426, 484, 490, 581 & 610 nm to estimate the concentrations of Chl-a, Suspended Sediments and CDOM in case-Ⅱ waters.