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A Spectrally Selective Attenuation Mechanism‐Based K par Algorithm for Biomass Heating Effect Simulation in the Open Ocean
Author(s) -
Chen Jun,
Zhang Xiangguang,
Xing Xiaogang,
Ishizaka Joji,
Yu Zhifeng
Publication year - 2017
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2017jc013101
Subject(s) - attenuation , photosynthetically active radiation , biomass (ecology) , photic zone , satellite , residual , attenuation coefficient , radiation , environmental science , algorithm , wavelength , remote sensing , ocean color , atmospheric sciences , meteorology , mathematics , optics , geology , photosynthesis , physics , chemistry , oceanography , phytoplankton , biochemistry , organic chemistry , astronomy , nutrient
Quantifying the diffuse attenuation coefficient of the photosynthetically available radiation ( K par ) can improve our knowledge of euphotic depth ( Z eu ) and biomass heating effects in the upper layers of oceans. An algorithm to semianalytically derive K par from remote sensing reflectance ( R rs ) is developed for the global open oceans. This algorithm includes the following two portions: (1) a neural network model for deriving the diffuse attention coefficients ( K d ) that considers the residual error in satellite R rs , and (2) a three band depth‐dependent K par algorithm (TDKA) for describing the spectrally selective attenuation mechanism of underwater solar radiation in the open oceans. This algorithm is evaluated with both in situ PAR profile data and satellite images, and the results show that it can produce acceptable PAR profile estimations while clearly removing the impacts of satellite residual errors on K par estimations. Furthermore, the performance of the TDKA algorithm is evaluated by its applicability in Z eu derivation and mean temperature within a mixed layer depth ( T ML ) simulation, and the results show that it can significantly decrease the uncertainty in both compared with the classical chlorophyll‐a concentration‐based K par algorithm. Finally, the TDKA algorithm is applied in simulating biomass heating effects in the Sargasso Sea near Bermuda, with new K par data it is found that the biomass heating effects can lead to a 3.4°C maximum positive difference in temperature in the upper layers but could result in a 0.67°C maximum negative difference in temperature in the deep layers.