"As an aside, the file in question does not have any valid SST retrievals over
the lake. The qual_sst flag indicates the data are all cloud covered."
I'd like to ask several questions.
1. SST data has already some null value in the Ocean area.
We first consider these areas are covered by cloud.
Will you inform me what is the definition of the null SST area?
2. We checked the "qual_sst", and the value of Suwa Lake is 3.
So it means "Bad Cloud/ice/or atmospheric correction failed",
according to table 1 of the following site.
We need to separate "cloud" and "ice", so we would use the "flags_sst".
Will you kindly inform me to separate the cloud pixel.
If the bit description is following, the pixels with more than 2^15 (=32768)
We checked the range of value.
"flags_sst" has two bands, the range of band 1 is from 0 to 537,920,320
(What does this value mean?), and band 2 is from -32,736 to 18,464.
Which band should we use?
2. I don't believe our products distinguish between cloud and ice. But yes, since CLOUD is flagged in bit 15, and 15 is the highest bit, any value >= 2^15 means a cloud pixel.
3. There is only one flags_sst dataset, with no band dimension.
short flags_sst(number_of_lines, pixels_per_line) ;
Perhaps the first "band" you mentioned is actually l2_flags?
int l2_flags(number_of_lines, pixels_per_line) ;
Decode those values using l2_flags:flag_meanings, or the table at https://oceancolor.gsfc.nasa.gov/atbd/ocl2flags/
537920320 = 2^29 + 2^20 + 2^9 + 2^8 + 2^6, indicating that the flags HIPOL, MODGLINT, CLDICE, STRAYLIGHT, and COASTZ are set.
Our land/water mask flags only the largest inland water bodies. At 15 sq km, Lake Suwa is probably flagged as land.
Our standard products do not attempt to process chlorophyll or SST over land. Your best bet is to generate l2 products yourself, using the "proc_land=1" flag.
Bit 15 of SST Quality Flags.
>Lake Suwa is probably flagged as land.
OK, but I confirmed the value of SST, it had some pixels of water temperature.
We wonder whether we can use it, or not.
>Your best bet is to generate l2 products yourself, using the "proc_land=1" flag.
Will you kindly inform me how to generate l2 product by myself?
You mean that we should use level 1 calibrate radiance data, and calculate SST value?
The attachment of the file is possible?
And I mean SST (not SST_CLOUD) is set in Suwa Lake, though you mentioned that the small lake is
dealt as land.
>Our land/water mask flags only the largest inland water bodies. At 15 sq km, Lake Suwa is probably flagged >as land. Our standard products do not attempt to process chlorophyll or SST over land.