I have a question about the MOD35 product, more specifically the Cloud Flag - 3.9-11 μm test. How can I find out if the test was performed and therefore the result is 0, or because low clouds were detected?
In the MODIS Cloud Mask User's Guide, in Table 3 (Bit Description of MODIS Cloud Mask Quality Assurance SDS), I did not find this test, but only the 3.7-11μm test.
The aim of my analysis is to investigate the occurrence of low clouds, for which I would first like to filter out the low clouds.
An answer would be very helpful.
Many thanks in advance.
With kind regards
Samira
MOD35 Cloud Flag - 3.9-11 μm Quality Assurance
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Re: MOD35 Cloud Flag - 3.9-11 μm Quality Assurance
Dear Samira Zander:
Yes, you are looking at the right table/values, but most likely at an old document.
The most recent QA documentation (https://atmosphere-imager.gsfc.nasa.gov/sites/default/files/ModAtmo/documents/QA_Plan_C61_Master_2021_09_22.pdf) correctly reports the 3.9-11um test in the table at page 37-39.
Additionally, the 3.7um channel is not used to perform any test in the MOD35 code, so it is safe to assume 3.9um wherever the documentation mentions 3.7um.
Yes, you are looking at the right table/values, but most likely at an old document.
The most recent QA documentation (https://atmosphere-imager.gsfc.nasa.gov/sites/default/files/ModAtmo/documents/QA_Plan_C61_Master_2021_09_22.pdf) correctly reports the 3.9-11um test in the table at page 37-39.
Additionally, the 3.7um channel is not used to perform any test in the MOD35 code, so it is safe to assume 3.9um wherever the documentation mentions 3.7um.
Regards,
LAADS User Services
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