Cloud mask for CZCS

[x3033x]

Dear Support,

I wonder how to set cloud_wave and cloud_thresh for CZCS processing in l2gen. I downloaded a CZCS L2 file (C1984006123815.L2_MLAC_OC.nc) from OB.DAAC, and its input_parameters recorded cloud_wave=865 and cloud_thresh=0.027, but I assumed the recorded values were not correct for CZCS.

Thanks,
Cheng

[OB.DAACx - SeanBailey]

I can see how that would be confusing, since CZCS doesn't have an 865band
The value listed for cloud_wave is the "requested" value (what was input to the code). The code finds the closest wavelength to the requested value. If you run l2gen on the parent L1A file, you would see this reported in the log output:

Using 670.0 nm channel for cloud flagging over water.
Using 443.0 nm channel for cloud flagging over land.

Sean

[x3033x]

Thank you Sean for the answer. I can understand 670 nm is the real band used in the code. Then, I wonder what value of the cloud threshold is used for 670 nm. I checked the info stored in CZCS L2 data but saw cloud_thres=0.027.

Best,
Cheng

[OB.DAACx - SeanBailey]

The threshold is 0.027 as stated.

Sean