Retrieval of diffuse attenuation coefficient in the China seas from surface reflectance

Area of Science:

• Oceanography
• Remote Sensing
• Marine Optics

Background:

• Accurate diffuse attenuation coefficient (Kd(490)) estimation is vital for China seas ecosystem health.
• Previous Kd(490) models showed poor retrieval quality in this region.
• In situ Kd(490) data varied widely (0.029–10.3 m⁻¹).

Purpose of the Study:

• Evaluate existing Kd(490) models in China seas coastal waters.
• Develop and validate new, accurate Kd(490) algorithms for the region.
• Improve retrieval of underwater light availability for marine ecosystems.

Main Methods:

• Evaluated three typical Kd(490) models using 306 in situ optical data sites.
• Developed new Kd(490) algorithms based on semi-analytical retrieval of absorption and backscattering coefficients.
• Utilized reflectance data from MODIS and MERIS sensors.

Main Results:

• Existing empirical and semi-analytical models significantly underestimated Kd(490).
• New algorithms achieved a mean ratio of 1.05 and 4.6% relative difference.
• Estimates from new algorithms were reliable within a factor of 1.9 (95% CI).

Conclusions:

• Existing Kd(490) algorithms require regional fine-tuning for China seas.
• Proposed new algorithms demonstrate significant improvement for accurate Kd(490) retrieval.
• Enhanced Kd(490) estimation supports better understanding of China seas marine ecosystems.