• PDF / 362,833 Bytes
• 8 Pages / 595.276 x 790.866 pts Page_size
• 12 Downloads / 168 Views

DOWNLOAD

REPORT

---

RESEARCH ARTICLE

A Simple Semi-Analytical Model for Estimating Absorption Coefficients of Optically Active Constituents in the West Florida Shelf Dacheng Wang & Ling Peng & Tianhe Chi & Xiaojing Yao

Received: 22 August 2014 / Accepted: 17 November 2014 / Published online: 10 February 2015 # Indian Society of Remote Sensing 2015

Abstract The objectives of this paper are to validate the applicability of a multi-band quasi-analytical algorithm (QAA) in retrieval absorption coefficients of optically active constituents in turbid coastal waters, and to further improve the model using a proposed semi-analytical model (SAA). The ap(531) and ag(531) semi-analytically derived using SAA model are quite different from the retrievals procedures of QAA model that ap(531) and ag(531) are semi-analytically derived from the empirical retrievals results of a(531) and a(551). The two models are calibrated and evaluated against datasets taken from 19 independent cruises in West Florida Shelf in 1999–2003, provided by SeaBASS. The results indicate that the SAA model produces a superior performance to QAA model in absorption retrieval. Using of the SAA model in retrieving absorption coefficients of optically active constituents from West Florida Shelf decreases the random uncertainty of estimation by >23.05 % from the QAA model. This study demonstrates the potential of the SAA model in absorption coefficients of optically active constituents estimating even in turbid coastal waters. Keywords Remote sensing . Coastal water . Absorption coefficient . Semi-analytical model

Introduction Absorption coefficient is an inherent optical property. It has long been known that the visible radiation upwelling from a natural water body is partially dictated by the absorption coefficients of the optically active constituents residing within D. Wang : L. Peng (*) : T. Chi : X. Yao Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing, China e-mail: [email protected]

that water body, while the water is depth enough so that the data is free from bottom influence. Therefore, reliable interpretation of satellite measurements of water color (i.e., extracting the co-extant concentration of the optically active constituents responsible for the record colour) is dependent upon a thorough understanding of the absorption coefficients pertinent to the water body under consideration (Binding et al. 2008; Chen et al. 2014a). Morel and Prieur (1977) indicated that the nature waters could be divided into Case I and Case II types. Initially the determination of absorption coefficients focused almost entirely on Case I waters. However, due to the additional number of organic and inorganic optically active constituents present in Case II waters and the potentially large variability in the inherent optical properties of each of these optically active constituents, models based solely upon chlorophyll-bearing biota are invalid when applied to Case II waters (Carder et al. 2003; Matthews 2011). Methods to accurately retrieve absorptio