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.