Semi-empirical correction algorithm for AC-9 measurements in a coccolithophore bloom.

Area of Science:

• Ocean optics
• Biogeochemistry
• Remote sensing

Background:

• AC-9 measurements of absorption and attenuation coefficients in coccolithophore blooms are insufficient for accurate radiance transfer modeling.
• Standard scattering correction algorithms do not account for wavelength-dependent scattering phase functions.

Purpose of the Study:

• To modify the standard AC-9 scattering correction algorithm to include wavelength dependence.
• To improve the accuracy of radiance transfer models for coccolithophore blooms.

Main Methods:

• Introduced an extra term, F(lambda, lambda(r)), into the AC-9 scattering correction algorithm.
• Adjusted absorption and scattering values within Hydrolight radiance transfer calculations to match in situ measurements of downward irradiance (E(d)) and upward radiance (L(u)).
• Validated the modified algorithm using data from an Emiliania huxleyi bloom in the western English Channel.

Main Results:

• A single value of F(lambda, lambda(r)) = 1.4 provided satisfactory agreement between modeled and observed profiles at 488 nm.
• The modified algorithm successfully constrained radiance transfer models with in situ data.
• Significant wavelength dependence was observed in the ratio of backscattering (b(b)) to total scattering (b).

Conclusions:

• The modified AC-9 scattering correction algorithm improves radiance transfer model accuracy for coccolithophore blooms.
• Accounting for wavelength-dependent scattering is crucial for accurate optical modeling in these environments.
• Further research is needed to fully understand the implications of wavelength-dependent scattering in marine optical properties.