Hello to all respectable team
I am using SNAP V8.0 and I want to validate the atmospheric correction using C2RCC for S3 OLCI.
I’ve got a graph process that does the following:
1- Downloaded the required data from AURAOMI and NCEP and added the .hdf files in folder, making the the path, D:\C2RCC\c2rcc_ancillary\2020\324 and added this path in the atmospheric aux data path.
2- For salinity I changed it to 0.182234 as this is salinity of my lake.
3- For temperature I changed it from 15 to 16.
4- Run c2rcc and export the values of rrs and compared these values with my in situs spectra
5- I do reprojection to the c2rcc and again export the data and compare it with in situ spectra
6- added all rrs in one Colum start from ( B1 -B12) and added the In situ data in the second Colum and the third column for ID as in the attached, then I draw the data.
My questions are:
1- Is these process are correct or i need to calculate the real values of TSM and CHL of my lake?
2- Why the scale of grave is not same?
Thank you so much
Well, the relationship does not look bad…
Do you know if you are comparing the same kind of units? Satellite Rrs is in sr-1.Is your in situ data also measured in sr-1 or is maybe water leaving radiance? In any case, your “Rrs” is too high for water measurements.
Thank you Abruescas for your reply
I will check the unit of the measures data.
But I wonder as I already made this comparison also with a colite processor and GF1 data ( China satellite) and the scale was same , pls see the attachment.GF data is only four bands.
I do not know how to help here. Please review the bands your are selecting for C2RCC (rhow or rrs), run one test with default parameters to check if the data your are introducing is changing things or not. You can also download the standard L2 data and compare with ACOLITE and C2RCC.
I have checked the range of the output Rrs , the valuse are very high comparing to the in situ measurements, is there any recommendations to change any parameters in C2rcc or what could be the reasons for that. Here i attached the in situ data figure and range of out put Rrs.
Thank you in Advance
Uploading: insitu - observed .png…
I think you must be comparing the wrong units. Probably you have Lw (water leaving radiances) in your in situ, and Rrs (remote sensing reflectance) in C2RCC. Have you check to use the rhow or rhown values in the comparison instead of Rrs?