I am new to SNAP and currently looking for a way to perform atmospheric correction to MODIS L1C data generated from MODIS L1A data.
My intended steps are:
- Generate L1B data using modis_GEO and modis_L1B from SeaDAS-OCSSW.
- Generate L1C data using l2gen from SeaDAS-OCSSW with recommended settings:
*l2prod=latitude longitude polcor_iii polcor_vvv rhot_iii rhot_vvv sena senz sola solz
*# PROCESSING OPTIONS
*# ANCILLARY INPUTS Default = climatology (select ‘Get Ancillary’ to download ancillary files)
- Perform atmospheric correction using C2RCC.
The problem I encountered here is that if I directly use L1C data in C2RCC, it pops out an error message “invalid source product, band ‘rhot_412’ not found”.
By inspecting the band names, I found that the supposed rhot_412 band is named as ‘rhot_412_geophysical_data’. So I renamed it as ‘rhot_412’, and the error message changed to “invalid source product, band ‘rhot_443’ not found”.
Knowing that band names may be causing the problem, I used a band rename method (Rename/delete bands from product using a GRAPH-file) using BandMaths and BandMerge in the Graph builder to cut the ‘_geophysical_data’ string from all bands, but now the program is giving another error message: “Could not retrieve time information from source product”.
I wonder what measure should I take to solve this problem. Thanks a lot for any suggestions!