How to export the value of con_chl from S3 after C2RCC

Hi there,
I try to in situ data to compare with the con_chl after C2RCC, however, I could not fully export the value of it. I think I might used wrong approch to do it.

After I convert con_chl into a band, shall I just export con_chl band then load into ArcGIS to export it into csv file? or Can I export it into CSV file in SNAP?
Thanks

I think you don’t want to export all values of the chl_conc raster. Only export those you have in-situ data for. You can set Pins by geo-location and then export the values at those Pins.
See the help for the Pin Manager.
You can also define a mask for a certain region if you are interested.
Either draw a geometry on the image or import a shapefile or specify the WKT (Right click on image → “Geometry from WKT”). You can even use an expression to define a mask. Use as expression ‘true’ to mask the whole image.
Then select this mask and right click on the image and select “Export Mask Pixels”.
You can store the data either to the clipboard or to a file (file is preferred if the number of pixels gets bigger).

Is it possible to compare the insitu data with con_chl in SNAP for certain area?
Could I load raster point (from ArcGIS) into the SNAP and to find out the relationship between them?

Yes, this is possible. You can use the Correlative Plot or the Profile Plot.

You need to import a CSV file an ESRI shapefile which contains your in-situ data.
After importing the data, it becomes selectable in the dialog.

There is also a YouTube video about validation which shows the usage of both plots.
In the video description you find a link to a zip file. It contains an example of in-situ CSV file.

The CSV format is also explained in the help. Follow the highlighted link.