Earthdata Forum

Hello,

I read the cloud optical properties (ATBD) at https://oceancolor.gsfc.nasa.gov/resources/atbd/atmospheric/cop/.

" The algorithm is an implementation of the optical properties component (Platnick et al., 2003, 2017) of the CHIMAERA retrieval code (Wind et al., 2020), which has been applied widely to retrieve cloud optical properties from multispectral satellite measurements. The current implementation is to MODIS measurements as a proxy for the PACE OCI. "

I have some questions:

Take the "PACE_OCI.20241110T001719.L2.CLD.V2_0.NRT.nc" as an example.

(1) Does PACE OCI cloud cloud optical properties follow the algorithms at https://oceancolor.gsfc.nasa.gov/resources/atbd/atmospheric/cop/ ?

(2) "cot_16" : Cloud Column Water Path two-channel retrieval using the 1.6 um band and either the 0.65 um, 0.86 um, or 1.2 um band (specified in cld_non_abs_band)
"cot_16_21": Cloud Optical Thickness two-channel retrieval using the 1.6 um and 2.1 um bands
"cot_21": Cloud Optical Thickness two-channel retrieval using the 2.1 um band and either the 0.65 um, 0.86 um, or 1.2 um band (specified in cld_non_abs_band)
"cot_22": Cloud Optical Thickness two-channel retrieval using the 2.2 um band and either the 0.65 um, 0.86 um, or 1.2 um band (specified in cld_non_abs_band)

For MODIS cloud product, "cot" has been scaled to MODIS band 1 (0.66um). Do the ''cot_**" in PACE OCI cloud products do the same thing? or being scaled to another wavelength ?

Thank you.

Hi, sorry for the delayed response - I thought I had notifications on but apparently not, have fixed that now. We don't have a lot of documentation about the cloud products now as they are still "test" status but are expecting it will be more complete in the next reprocessing as we move toward "provisional" status. To answer your questions:

1. Yes, it's CHIMAERA as described at that link and papers. Note we are providing both MODIS-like 2.1 um and VIIRS-like 2.2 um retrievals.

2. Yes, it's representative of mid-visible COT (around 0.65 um).