Rrs values are varied a lot in different dates

Hello, I’m using latest version of SNAP for windows. I want to get Rrs values for a relatively small reservoir. I used Sentinel2 L1-C images and I got subset and resample for each image individually and used C2RCC processor to retrieve Rrs values. (I did all of this manually without using gpt). In the parameter windows for C2RCC processor I changed temperature, salinity and elevation according to my study area and didn’t change anything else. So far I retrieved Rrs for two images with the mentioned method. But I noticed the Rrs values are very different in those dates. Here is the result for 4 points,

First image:
2023-08-19 22_37_26-Window

Second image:

2023-08-19 22_37_36-Window

I’m wondering why this happens and how to fix the issue?


Sorry I hadn’t a good progression, in fact I faced another issue: For the first image I zoomed out the subset and as the result, all processes took more time (especially resampling). Strangely, some of the Rrs values had changed! Does it happen because the reservoir is small with respect to the satellite image? Why would the subset size affect Rrs and how to fix this issue too? Here is the new Rrs values: