This paper aims to describe the variability of
particulate absorption properties using a unique hyperspectral dataset collected in the Red Sea as part of the TARA Oceans
expedition. The absorption contributions by
phytoplankton (aph) and non-algal particles (aNAP) to the total particulate
absorption coefficients are determined using a numerical decomposition method (NDM). The NDM is validated by comparing the NDM derived values of aph and aNAP with simulated values of aph and aNAP are found to be in excellent agreement for the selected
wavelengths (i.e., 443, 490, 555, and 676 nm) with high
correlation coefficient (R2), low
root mean square error (RMSE), mean relative error (MRE), and with a slope close to unity. Further analyses showed that the total particulate absorption coefficients (i.e., ap(443)average = 0.01995 m−1) were dominated by phytoplankton absorption (i.e., aph(443)average = 0.01743 m−1) with a smaller contribution by non-algal particles absorption (i.e., aNAP(443)average = 0.002524 m−1). The
chlorophyll a is computed using the absorption based Line Height Method (LHM). The derived chlorophyll-specific absorption ((a*ph = aph(λ)/ChlLH)) showed more variability in the blue part of spectrum as compared to the red part of spectrum representative of the
package effect and changes in
pigmentcomposition. A new parametrization proposed also enabled the reconstruction of a*ph(λ) for the Red Sea. Comparison of derived spectral constants with the spectral constants of existing models showed that our study A(λ) values are consistent with the existing values, despite there is a
divergence with the B(λ) values. This study provides valuable information derived from the particulate absorption properties and its spectral variability and this would help us to determine the relationship between the phytoplankton absorption coefficients and chlorophyll a and its host of variables for the Red Sea.