1378 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 41, NO. 6, JUNE 2003 Satellite Hyperspectral Remote Sensing for Estimating Estuarine and Coastal Water Quality Vittorio E. Brando and Arnold G. Dekker Abstract—The successful launch of Hyperion in November 2000 bridged the gap between the high-resolution (spatial and spectral) airborne remote sensing and the lower resolution satellite remote sensing. Although designed as a technical demonstration for land applications, Hyperion was tested for its capabilities over a range of water targets in Eastern Australia, including Moreton Bay in southern Queensland. Moreton Bay was the only Australian Earth Observing 1 (EO-1) Hyperion coastal site used for calibration/validation activities. This region was selected due to its spatial gradients in optical depth, water quality, bathymetry, and substrate composition. A combination of turbid and humic river inputs, as well as the open ocean flushing, determines the water quality of the bay. The field campaigns were coincident with Hyperion overpasses, retrieved inherent optical properties, apparent optical properties, substrate reflectance spectra, and water quality parameters. Environmental noise calculations demonstrate that Hyperion has sufficient sensitivity to detect optical water quality concentrations of colored dissolved organic matter, chlorophyll, and suspended matter in the complex waters of Moreton Bay. A methodology was developed integrating atmospheric and hydrooptical radiative transfer models (MOD- TRAN-4, Hydrolight) to estimate the underwater light field. A matrix inversion method was applied to retrieve concentrations of chlorophyll, colored dissolved organic matter, and suspended matter, which were comparable to those estimated in the field on the days of the overpass. Index Terms—Coastal waters, imaging spectrometry, numerical radiative transfer modeling, remote sensing. I. INTRODUCTION T HE EARTH Observing One (EO-1) satellite is the first earth-observing platform of the National Aeronautics and Space Administration’s (NASA) New Millennium Program (NMP) designed for new technologies and strategies for improving the quality of observations for NASA’s future plan- etary and earth missions. The Hyperion Imaging Spectrometer is the first high spatial resolution imaging spectrometer to successfully orbit the earth [1]. The EO-1 orbit is almost synchronous with the Landsat-7 and the Terra platform. The results presented here form part of the Australian contribution to the Hyperion Science Validation Team (SVT) Southern Manuscript received July 1, 2002; revised January 8, 2003. This work was supported in part by the Commonwealth Scientific and Industrial Research Or- ganization Earth Observation Center and by the Cooperative Research Center for Coastal Zone, Estuary and Waterways Management. The authors are with the Commonwealth Scientific and Industrial Research Organization Land and Water, Canberra, ACT 2601, Australia (e-mail vittorio.brando@csiro.au; arnold.dekker@csiro.au). Digital Object Identifier 10.1109/TGRS.2003.812907 Hemisphere campaign. The coastal site of Moreton Bay in southeast Queensland, Australia, was chosen, as it has been studied extensively and has a number of major active coastal water quality monitoring and management projects. Moreton Bay (Fig. 1) serves as a multiuse resource for a large population in the Brisbane and southeast Queensland urban area and requires regular monitoring information to ensure this resource is being sustained. Research groups from the University of Queensland (UQ) and the Commonwealth Scientific and Industrial Research Organization (CSIRO) are cooperatively developing remote sensing solutions to environmental moni- toring [2]. During the SVT Southern Hemisphere campaign, Moreton Bay imagery was acquired six times from December 2000 to July 2001. A summer, autumn, and winter image are cloud free for Deception Bay (January 12, 2001, April 2, 2001, July 7, 2001). During each Hyperion overpass, a limited set of spec- troradiometric measurements and in situ sampling was carried out by the UQ in Deception Bay. Two extensive joint field cam- paigns were carried out in February 2001 and June 2001 to pa- rameterize a biooptical model for Moreton Bay in both opti- cally deep and shallow waters. The field campaign collected in- herent and apparent optical properties, as well as concentrations of water constituents and substrate reflectances. Using these data as input to an analytical optical model, it was possible to simulate the effect on subsurface irradiance reflectance at any range of water quality variable concentrations, such as colored dissolved organic matter, chlorophyll, and suspended matter present at the time of a Hyperion overpass (provided the specific inherent optical properties do not vary significantly). By inverting this analytical model, it becomes possible to de- termine the capacity of Hyperion to estimate concentrations of water quality variables with a known degree of precision and accuracy. The precision and accuracy of these estimates are a function of the sensitivity of Hyperion, of the preprocessing, and of the (inversion of the) analytical model. The resulting ap- proaches demonstrate the potential of hyperspectral data and se- lected bandwidths for water quality monitoring. II. IMAGE PREPROCESSING A. Radiometric Calibration During the first year of the science validation, we received Hyperion imagery at an “interim level of radiometric calibra- tion” Level 1A_2. The most recent radiometric calibration dis- tribution is at Level 1B_1, incorporating the knowledge gained 0196-2892/03$17.00 © 2003 IEEE