Colored dissolved organic matter absorption at global scale from ocean color radiometry observation: Spatio-temporal variability and contribution to the absorption budget
Résumé
A semi-analytical model (CDOM-KD2) based on the light vertical attenuation coefficient (Kd(λ)) has been
developed for estimating the absorption by colored dissolved organic matter, acdom(443), from ocean color
remote sensing at global scale. The performance of this new inversion model together with that of former models
by Shanmugam (2011) (S2011), Chen et al. (2017) (C2017) and Aurin et al. (2018) (A2018) was evaluated from
in situ and matchup validation data sets gathering worldwide distributed samples. An overall consistency in the
acdom(443) estimated from S2011, C2017 and CDOM-KD2 models with a slightly better performance of the latter
method was observed (MAPD of 27.42% and 30.85% for open ocean with in situ and satellite data, respectively),
emphasizing the possible specific assessment of acdom(443) dynamics from satellite remote sensing over the
global ocean including the most oligotrophic waters. At 443 nm the global average relative contribution of
acdom(443) to the absorption by colored detrital matter, acdm(443) is of 61% ± 14%, while the contribution of
acdom(443) to the non-water absorption, anw(443), is of 35% ± 26%. Strong spatial disparities are however
observed for both acdom(443) temporal dynamics and relative contribution in the absorption budget. A decou-
pling is observed between acdom(443) and particulate detrital (i.e. non-living) matter and phytoplankton in the
gyre areas where a low temporal variability is globally observed. This is contrasting with water masses influ-
enced by terrestrial inputs as well as in equatorial and subtropical areas impacted by main oceanic currents
where CDOM loads and acdom(443) contribution in the water absorption budget are more variable.
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