Question about the atmosphric correction of L2 WFR products


I have downloaded the L2 WFR products for deriving the water quality parameters, however, I found that
the reflectances of many pixels are negative. I supposed that this problem was caused by improper atmospheric correction (AC), and I want to change the AC method to the AAC method.

So I downloaded the corresponding L1 EFR products and performed AC using the C2RCC toolbox, I want to make sure that whether the AC method used in C2RCC is the AAC rather than BAC.

In addtion, I found that the C2RCC tbx can output the remote sensing reflectance, but it is denoted by “rrs”, as far as I know, the remote sensing reflectance (above-surface ) is usually represented by the “Rrs”, while the “rrs” denotes the below-surface remote sensing reflectance. Thus, whether the output remote sensing result is the below-surface remote sensing reflectance?

Thank you!

With C2RCC you can also obtain rhow, in fact rrs is optional (you have to select it in the function). C2RCC is similar to the ACC of the ESA standard products, but not exactly the same. ACC is v1 and C2RCC in SNAP is v2, that means the min/max ranges of the C2 water types were enlarged for v2.