Colored Dissolved Organic Matter Absorption At Global Scale From Ocean Color Radiometry Observation: Spatio-Temporal Variability And Contribution To The Absorption Budget

A semi-analytical model (CDOM-KD2) based on the light vertical attenuation coefficient (K-d(lambda)) has been developed for estimating the absorption by colored dissolved organic matter, a(cdom)(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 a(cdom)(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 a(cdom)(443) dynamics from satellite remote sensing over the global ocean including the most oligotrophic waters. At 443 nm the global average relative contribution of a(cdom)(443) to the absorption by colored detrital matter, a(cdm)(443) is of 61% +/- 14%, while the contribution of a(cdom)(443) to the non-water absorption, anw(443), is of 35% +/- 26%. Strong spatial disparities are however observed for both a(cdom)(443) temporal dynamics and relative contribution in the absorption budget. A decoupling 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 influenced by terrestrial inputs as well as in equatorial and subtropical areas impacted by main oceanic currents where CDOM loads and a(cdom)(443) contribution in the water absorption budget are more variable.