Hello,
I am using the Biophysical Processor in SNAP v.5.0 to calculate chlorophyll content. When I examine the output raster in SNAP I can see that the units are g/cm2. The same is also stated in the ATBD and there one can also find that the valid range is 0-600 g/cm2. From the ATBD it is clear that the calculated parameter is actually canopy chlorophyll content (CCC, or the product of LAI and the chlorophyll concentration per unit leaf area).
Maybe I am wrong but CCC values of several hundred grams per square cm (of the ground surface?) are too high. So, I was wondering if there is a mistake in the documentation regarding the units. For me, micro gram / cm2 seem to be more realistic unit for CCC output of SNAP. I would be grateful if someone could help me in interpreting the CCC values produced by the Biophysical Processor. Thanks in advance.
Regards,
Petar
I have the same question. Could you find an answer in the meantime? Thanks.
No, I couldn’t.
Did anyone find out the answer in the meantime?
Hello everyone!
I am using Snap 6.0.
Unfortunately I have the same questions. I have checked with the ATBD (http://step.esa.int/docs/extra/ATBD_S2ToolBox_L2B_V1.1.pdf) as well.
I would also like to note the fact that when someone uses the Biophysical processor in SNAP the index is named Cab and not CCC. After you produce it, it appears as lai-cab and it is measured in g/cm2 . My values are up to 700 g/cm2 with a mean value of 150 g/cm2 which can’t be valid.
I can see in the relevant guide page 21 that the units for Cab Leaf Chlorophyll (Cab) content is µg/cm 2 .
Here it also presents Cab as the index calculated by SNAP Biophysical Processor.
In this research with regard to Cab and CCC in the Himalayan Forests it says that for the specific study area “Leaf level chlorophyll (Cab) estimates ranged from 1.72 µg/ cm2 to 68.08 µg /cm2, whereas canopy level chlorophyll (CCC) estimates were ranging from 0.04 g/ m 2 to 2.63g/ m 2 . ”
Thank you for your time!
I am also having a similar issue with one of the biophysical parameters. I am not sure what is the unit for CWC (canopy water content). I was also referring to the ATBD, but the unit changes as I kept reading the article.