Remote sensing of inherent and apparent optical properties in optically complex shelf seas

  • Catherine Mitchell

Student thesis: Doctoral Thesis


Variability in the patterns of ocean colour is frequently observed in shelf seas, where a combination of phytoplankton cells, mineral particles and coloured dissolved organic matter are driving the optical properties of the water column. Understanding the contributions of each material to the total optical properties is essential for understanding and monitoring the processes which affect shelf sea ecosystems. Lee et al. (2002, 2005b, 2007, 2009, 2013) developed a method for the recovery of the absorption, backscattering and mean diffuse attenuation co-efficients and the euphotic depth from the remote sensing reflectance. Using the Irish Sea as a study site, the procedure of Lee et al. and two empirical methods for recovering the euphotic depth (Cunningham et al., 2013 and Zhao et al., 2013), were evaluated. The methods were initially adjusted based on a regional bio-optical model, then validated against field data with excellent recoveries of all parameters. By considering the backscattering to absorption ratios of phytoplankton and mineral particles, a new method for separating the total absorption coefficient recovered by the quasi-analytical algorithm into the phytoplankton and mineral components was developed. Application of this method to the bio-optical model created for the Irish Sea recovered phytoplankton and mineral absorption coefficients which were well correlated with the modelled values. The sensitivity of the absorption partitioning procedure to the assumption made about CDOM variability was evaluated, demonstrating the phytoplankton and mineral absorption coefficients could be recovered within the Irish Sea with root mean square errors of 0.02 m⁻¹ and 0.009⁻¹ respectively. The inversion methods developed and validated were applied to eight years of MODIS data. This showed both spatial and temporal variability for all parameters, which corresponded to different mixing regimes and were explained in terms of phytoplankton cells and mineral particles. The results obtained from the satellite imagery have demonstrated that optical remote sensing can be used to provide an insight into shelf sea ecosystems.
Date of Award22 Apr 2015
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsNERC (Natural Environment Research Council)

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