An Improved Bio-Optical Model for Remote Sensing of Phytoplankton Absorption Coefficient in Global Waters

A new empirical model has been developed and validated for determining phytoplankton absorption coefficient a
ph
(λ) in global waters using high-quality in-situ hyperspectral remote sensing reflectance R
rs
(λ) and MODIS-Aqua data. The strong correlation between the a
ph
(λ) and the ratio of R
rs
(λ) at 490 and 665 nm has been exploited to model the data. An extensive in-situ data set that has 1290 independent stations with co-existing R
rs
(λ) and a
ph
(λ) values that spans global oceans is utilized for the training and validation of the model. The developed model delivers acceptable results in terms of statistical measures. The model gives a maximum mean absolute percent error of 0.22, R
²
value not less than 0.72, and slope estimates very close to 1 for all visible spectral bands. The model has been further extended to analyze the variability of a
ph
(443) and a
ph
(665) over the global oceans using MODIS-Aqua images acquired from the NASA Ocean Color repository.