PACE L2 OCI wavelength bands

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lucas.barbedo
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PACE L2 OCI wavelength bands

by lucas.barbedo » Thu May 30, 2024 11:03 am America/New_York

PACE L2 OCI data from Earthdata (short name: PACE_OCI_L2_AOP_NRT, PACE_OCI_L2_IOP_NRT, ...),
for example: "https://obdaac-tea.earthdatacloud.nasa.gov/ob-cumulus-prod-public/PACE_OCI.20240520T180624.L2.OC_AOP.V1_0_0.NRT.nc"
has a parameter wavelength_3d assigned to Rrs and Kd (similar in for PACE_OCI_L2_IOP_NRT products)
Rrs (number_of_lines, pixels_per_line, wavelength_3d)
however, I can not find any attributed to wavelength_3d that could designed respective bands (seems me that wavelength_3d has 0 values).

In the L1B files, we can see the band parameters in the netcdf-file group parameter: 'sensor_band_parameters'
For example:
blue_wavelength: 314.5 316.1 318.1 ... 603.3 605.7
red_wavelength: 600.4 602.9 605.4 ... 892.1 894.6
however, the L2 products do not have the same number of bands. I am looking for the identification the wavelength assigned for each band. Where can I find this information?

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dagmarm
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Re: PACE L2 OCI wavelength bands

by dagmarm » Fri May 31, 2024 6:19 am America/New_York

Hi Lucas,

I have been looking for the same information and we found this solution (in python):

from xcube.core.store import new_data_store
local = new_data_store("file", root=<folder with PACE L2 data>)
wl_ = local.open_data(<filename>, group = 'sensor_band_parameters')
wl = wl_.wavelength_3d

Kind regards,
Dagmar

OB.DAAC - SeanBailey
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Re: PACE L2 OCI wavelength bands

by OB.DAAC - SeanBailey » Fri May 31, 2024 3:29 pm America/New_York

Correct, the wavelength_3d is in the sensor_band_parameters group.

Some background...
The sensor_band_parameters group contains informational parameters and has been part of the L2 ocean color metadata since the days of SeaWiFS and includes a wavelength parameter that is the list of wavelengths for the sensor - not necessarily related to the wavelengths in the products... With PACE, we have a need to have a wavelength parameter that is NOT the full sensor set, so we created the new wavelength_3d parameter. This is the list of wavelengths associated with the 3 dimensional arrays in the L2 file (e.g. Rrs). We are considering redefining this parameter to be a dimensional quantity (dimension wavelength, instead of wavelength_3d, with a corresponding wavelength variable).

Regards,
Sean

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