Help! How can i find published signal to noise ratio information?

I wonder if anyone can point me to where I might be able to find this information?

I'm particualrly interested in where I can find SNR details for both S2 and L8/9.

I am currently doing a seagrass classsification project and often i see reflection values of 0.05. Hence I imagine a low SNR will greatly improve my results especially when classifying benthos at depth.

Thanks in advance.