SLC-IW data shows sudden change in spectrum

Dear researchers,
I am using TOPS SLC-IW data, problem is with sudden change in spectrum. I need to extract ocean circulation parameters from one swath of SLC-IW. i.e., in azimuth at pixel 2000 we can see, values are changing very sudden, whcih is impractical.
is this a problem with doppler centroid?
please guide me on it. Many thanks in advanceRVS_mask