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MERIS Retrieval of Water Quality Components in the Turbid Albemarle-Pamlico Sound Estuary, USA
Citation:
Sokoletsky, L. G., R. S. LUNETTA, M. S. Wetz, AND H. W. Paerl. MERIS Retrieval of Water Quality Components in the Turbid Albemarle-Pamlico Sound Estuary, USA. Remote Sensing. MDPI, Basel, Switzerland, 3(4):684-707, (2011).
Impact/Purpose:
Ocean color was first measured from space in 1979 and has since provided a synoptic view of near-surface water quality components (WQCs) like chlorophyll a (Chl), volatile suspended solids (VSS), fixed suspended solids (FSS), total suspended solids (TSS), and absorption of chromophoric dissolved organic matter (aCDOM). Subsequently, a number of ocean color satellite missions have been used to monitor phytoplankton biomass and other biogeochemical variables across temporal (daily to annual) and spatial (kilometers to ocean basin) scales (Boss et al. 2008). Numerous satellite remote-sensing empirical and semi-empirical algorithms for water color retrieval (especially for oceanic phytoplankton) have been created during this time (Campbell and Esaias 1983; O’Reilly et al. 1998; Dall’Olmo and Gitelson 2005).
Description:
Two remote-sensing optical algorithms for the retrieval of the water quality components (WQCs) in the Albemarle-Pamlico Estuarine System (APES) have been developed and validated for chlorophyll a (Chl) concentration. Both algorithms are semiempirical because they incorporate some models of optical processes in the atmosphere, water, and air/water interface. One incorporated a very simple atmospheric correction and modified quasi-single-scattering approximation (QSSA) for estimating the spectral Gordon’s parameter and WQCs, while the second estimated WQCs directly from the top of atmosphere (TOA) satellite radiance. A modified version of Global Meteorological Database for Solar Energy and Applied Meteorology (METEONORM) was used to estimate atmospheric transmittance along the sun to water path; while the atmospheric transmittance along the target to satellite path was estimated using the reciprocity principle for atmospheric transmittance. Two databases, the Ferry-Based Monitoring (FerryMon) Chl data collected in the NRE (n = 631) and Pamlico Sound (n = 362), and Medium Resolution Imaging Spectrometer (MERIS) satellite imagery collected in 2006–2009 across the Neuse River Estuary (NRE), provided quasi-coinciding samples for Chl algorithms development. Results indicated a coefficient of determination (R2) of 0.68 and mean-normalized root-mean-squares errors of 54% in the NRE — without atmospheric corrections. The simple atmospheric correction tested provided no performance improvements. Algorithm performance demonstrated the applicability of the algorithms to potentially support long-term operational WQCs satellite monitoring in the APES.