A five channel chlorophyll concentration algorithm applied to SeaWiFS data processed by SeaDAS in coastal waters

Chlorophyll-a concentration derived from the Sea-viewing Wide Fieldof-view Sensor (SeaWiFS) after applying the current SeaWiFS Data Analysis System (SeaDAS) processing tools appears to be higher than reality in coastal areas, particularly from late summer to early spring when optical properties of water are dominated by yellow substances and suspended matter. As a complement to the SeaWiFS standard procedure addressing clear water, empirical algorithms can bring immediate progress for observing the coastal domain. This paper proposes to modify the SeaWiFS Ocean Colour 4 band algorithm (OC4) by including the 412 and 555 channels. The effect of the suspended matter on the ratios used as inputs in OC4 is revealed by the 555 channel whereas the atmospheric over-correction and the absorption by yellow substances are related to the 412 channel. Based on a dataset located in the English Channel and on the continental shelf of the Bay of Biscay, a parametrization of the relationship between the OC4 ratio and the 412 and 555 bands has been empirically proposed for different chlorophyll concentrations. Application of a lookup table, relating triplets (OC4 band ratio, 412 and 555 bands) to chlorophyll-a concentration, provides realistic concentration maps likely to satisfy the needs of researchers involved in environmental surveying or fishery management.

[1]  S. Maritorena,et al.  Atmospheric correction of satellite ocean color imagery: the black pixel assumption. , 2000, Applied optics.

[2]  P. Tréguer,et al.  Impacts of high-nitrate freshwater inputs on macrotidal ecosystems. II. Specific role of the silicic acid pump in the year-round dominance of diatoms in the Bay of Brest (France) , 1997 .

[3]  Mar Ecol Prog,et al.  Improved HPLC method for the analysis of chlorophylls and carotenoids from marine phytoplankton , 2022 .

[4]  K. Carder,et al.  Semianalytic Moderate‐Resolution Imaging Spectrometer algorithms for chlorophyll a and absorption with bio‐optical domains based on nitrate‐depletion temperatures , 1999 .

[5]  Prieur,et al.  Analysis of variations in ocean color’ , 2000 .

[6]  M. Kahru,et al.  Ocean Color Chlorophyll Algorithms for SEAWIFS , 1998 .

[7]  K. Carder,et al.  Reflectance Model for Quantifying Chlorophyll- a in the Presence of Productivity Degradation Products , 1991 .

[8]  A. Bricaud,et al.  Theoretical results concerning light absorption in a discrete medium, and application to specific absorption of phytoplankton , 1981 .

[9]  Kenneth J. Voss,et al.  MODIS Normalized Water-leaving Radiance Algorithm Theoretical Basis Document ( MOD 18 ) Version 4 Submitted by Howard , 1999 .

[10]  H. Gordon,et al.  Clear water radiances for atmospheric correction of coastal zone color scanner imagery. , 1981, Applied optics.

[11]  André Morel,et al.  A multiple scattering algorithm for atmospheric correction of remotely sensed ocean colour (MERIS instrument): Principle and implementation for atmospheres carrying various aerosols including absorbing ones , 1999 .

[12]  F. Muller‐Karger,et al.  AVIRIS calibration and application in coastal oceanic environments - Tracers of soluble and particulate constituents of the Tampa Bay coastal plume , 1993 .

[13]  J. Froidefond,et al.  SeaWiFS data interpretation in a coastal area in the Bay of Biscay , 2002 .

[14]  L. Prieur,et al.  Analysis of variations in ocean color1 , 1977 .

[15]  Menghua Wang,et al.  Retrieval of water-leaving radiance and aerosol optical thickness over the oceans with SeaWiFS: a preliminary algorithm. , 1994, Applied optics.

[16]  Jim Aiken,et al.  The atmospheric correction of water colour and the quantitative retrieval of suspended particulate matter in Case II waters: Application to MERIS , 1999 .

[17]  T. Platt,et al.  Analytic model of ocean color. , 1997, Applied optics.

[18]  S. Hooker.  An overview of SeaWiFS and ocean color , 1992 .

[19]  C. Lorenzen,et al.  DETERMINATION OF CHLOROPHYLL AND PHEO‐PIGMENTS: SPECTROPHOTOMETRIC EQUATIONS1 , 1967 .