IOP meanings from C2RCC

After running C2RCC, I have IOP estimates (apig, adet, bpart, bwit). The description for bpart is “Scattering coefficient of marine paticles at 443 nm” and bwit is “Scattering coefficient of white particles at 443 nm”. Is this truly a scattering coefficient, or a backscattering coefficient? The ATBD makes me think it is a backscattering coefficient, since it is derived using bb measurements from the NOMAD dataset. Any clarification would be helpful. Thanks!

C2RCC Processor

The Case 2 Regional CoastColour (C2RCC) atmospheric correction is a full spectrum version using a set of neural networks which are trained on simulated top-of-atmosphere reflectance. The raditiave transfer simulations include the full ocean and atmosphere system, i.e. a specific water model is included in the simulations. C2RCC is used to generate the Case 2 water products in Sentinel 3 OLCI standard ESA products, as well as in the upcoming MERIS 4th Reprocessing.

…marine particles… …white particles…
What is conceptual difference between these two types of particles?
In particular, what kind of phenomena “white particles” could mean in real life?

Thank you for possible opinions!