Application of Polarimetry in Ocean Color Sensing

Phytoplankton constitute the base the of the aquatic food web and are a primary driver of biogeochemical processes in the ocean. The concentration of chlorophyll-α ([Chl-α]) were being used as a proxy to quantify phytoplankton activity in ocean. Its concentration in ocean can be obtained through analysis spectral bands variance in remote sensing reflectance measurement(e.g. SeaWIFS Chl-α algorithm), which was widely used for being the most efficient and cost effective method thanks to its ability to synoptic sampling in large area with high revisit frequency.¹

Remote sensing of [Chl-α] has been difficult in coastal waters due to present of high concentration of terrestrial substances (e.g. mineral particles and humus). These substances contribute significantly to light absorption and scattering in water, but their concentration does not covary with Chl-α.² Recent theoretical and empirical studies have shown polarimetry as an effective means to solving this problem by improving the understanding of optical property of costal water. ^3,4

Citation:

1. Zheng, G. & DiGiacomo, P. M. Remote sensing of chlorophyll-a in coastal waters based on the light absorption coefficient of phytoplankton. Remote Sens. Environ. 201, 331–341 (2017).

2. Jamet, C. et al. Going Beyond Standard Ocean Color Observations: Lidar and Polarimetry. Front. Mar. Sci. 6, (2019).

3. Chami, M. & Platel, M. D. Sensitivity of the retrieval of the inherent optical properties of marine particles in coastal waters to the directional variations and the polarization of the reflectance. J. Geophys. Res. Ocean. 112, 9494–9509 (2007).

4. Ibrahim, A., Gilerson, A., Chowdhary, J. & Ahmed, S. Retrieval of macro- and micro-physical properties of oceanic hydrosols from polarimetric observations. Remote Sens. Environ. 186, 548–566 (2016).