Physical, Bio-Optical State and Correlations in North–Western European Shelf Seas

Shungudzemwoyo Garaba,Oliver Zielinski,Daniela Voß

doi:10.3390/rs6065042

Shungudzemwoyo Garaba, Oliver Zielinski + Show 1 more

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https://doi.org/10.3390/rs6065042

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Journal: Remote sensing	Publication Date: May 30, 2014
Citations: 26	License type: CC BY 3.0

Affiliation: Carl von Ossietzky University of Oldenburg

Abstract

Color of seawater has become an integral tool in understanding surface marine ecosystems and processes. In this paper we seek to assess the correlations and consequently the potential of using shipborne remote sensing products to infer marine environmental parameters. Typical seawater parameters are chlorophyll–a (chl–a), colored dissolved organic material (CDOM), suspended particulate material (SPM), Secchi–disk depth (SDD), temperature, and salinity. These parameters and radiometric quantities were observed from a total of 60 stations covering German Bight, North Sea, Inner Seas, Irish Sea, and Celtic Sea. Bio-optical models developed in this study were used to predict the in situ measured parameters, with low mean unbiased percent differences and absolute percent difference less than 35%. Our investigations show that the use of ocean color products namely the Forel–Ule Index to infer seawater parameters is encouraging. The constrained spatial and temporal span of measured in situ parameters does limit the accuracy of our models. Absorption coefficients of the main color producing agents CDOM, chl–a, and inorganic fraction of SPM (iSPM) were determined to estimate absorption budgets. During the field campaign, iSPM was the primary light absorber over the spectral range (400–700 nm) although variabilities were observed in the regional seas.

Highlights

Active seawater constituents interact with sunlight depending on their inherent optical properties (IOPs), i.e., ability to absorb, attenuate, re-emit, reflect, or scatter light
It is presumed that perceived color of seawater in the northwest European shelf seas (NWES) is strongly driven by colored dissolved organic material (CDOM) and suspended particulate material (SPM) chl–a plays a seasonal and local role for example in the Central North Sea [32,33,34,35]
A summary of the in situ measurements collected during the R/V Heincke cruise HE302 is given in

Summary

Introduction

Active seawater constituents interact with sunlight depending on their inherent optical properties (IOPs), i.e., ability to absorb, attenuate, re-emit, reflect, or scatter light. Typical optically active seawater constituents responsible for color of seawater are colored dissolved organic matter (CDOM), chlorophyll–a (chl–a) a common pigment in phytoplankton, and suspended particulate material (SPM). These seawater constituents are known as color producing agents (CPAs). As CPAs are optically active seawater constituents their IOPs can be correlated to or influenced by seawater physical properties, such as salinity, temperature, and water transparency [1,2,3]. Its light absorption coefficient decays almost exponentially, from high absorption coefficients in the ultra–violet to close to zero towards red spectral range [5,6]

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