Calculating the Signal to Noise Ratio in Sentinel-1 GRD

Hi there,

I was wondering if it is possible to calculate the SNR in Sentinel-1 GRD products in the SNAP toolbox? I am using Sentinel-1 GRD products to create glacial velocity maps using offset tracking. I would like to obtain the SNR value of the final velocity output to calculate a spatial variable error (e.g divide velocity by SNR). I have been unable to find the SNR value in the products metadata.

Many thanks,