Estimation of Estuary Phytoplankton using a Web-based Tool for Visualization of Hyper-spectral Images

The development of Web-based tools for visualization and processing of hyper-spectral images has been slow. Memory and processing capabilities of personal computers may have precluded the development of Web-based tools. However, fast access to remote databases, increasing microprocessors' speed, and grid portals that provide interconnection between remote nodes sharing data and computing resources, make possible remote exploration and analysis of hyper-spectral data cubes. This paper presents a Web-based visualization tool for exploring moderate resolution imaging spectroradiometer (MODIS) data cubes. It provides capabilities for individual pixel's reflectance-spectra visualization, on-the-fly per-pixel calculation and visualization of chlorophyll-a andphytoplankton-carbon concentration values. The Web-based interface also generates normalized difference vegetation index images from the multi-spectral information contained in MODIS datasets. The tool is applied to estimate phytoplankton concentrations in the Saint Louis Bay estuary (Mississippi). Chlorophyll-a estimations produced by the Web-based tool compare well with in-situ measurements from a field survey performed during August 2001. Phytoplankton concentrations are calculated using those estimations of chlorophyll-a concentrations generated by the Web-based tool. The higher spatial resolution provided by the interface allowed estimating constituents concentrations at geographical locations near the coast.