Scattering error corrections for in situ absorption and attenuation measurements

Area of Science:

• Ocean optics
• In-situ measurements
• Light scattering

Background:

• The WETLabs AC-9 instrument is widely used for measuring ocean water properties.
• Accurate absorption and attenuation measurements are crucial for understanding aquatic ecosystems.
• Existing scattering error correction methods have limitations, particularly in complex water conditions.

Purpose of the Study:

• To develop a novel scattering error correction procedure for the WETLabs AC-9 absorption and attenuation sensors.
• To improve the accuracy of optical measurements by accounting for angular scattering artifacts.
• To provide a more robust method applicable to diverse oceanic and coastal waters.

Main Methods:

• Monte Carlo simulations were employed to derive weighting functions for angular scattering.
• A new iterative approach was developed, utilizing particulate backscattering ratio and Fournier-Forand phase functions.
• The method was validated using in situ data from clear, moderately turbid, and highly turbid coastal waters.

Main Results:

• The new correction procedure accurately models scattering effects for both absorption and attenuation measurements.
• Significantly higher absorption and attenuation values were observed compared to previous methods.
• Differences in spectral distribution of scattering signals were noted between the new and existing procedures.

Conclusions:

• The developed scattering error correction method offers improved accuracy for AC-9 optical measurements.
• This advancement is particularly beneficial for characterizing optical properties in turbid coastal waters.
• The new procedure provides more reliable data for ecological and biogeochemical studies.