Conversion of radiance to reflectance in MOBY data

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masudocn02
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Conversion of radiance to reflectance in MOBY data

by masudocn02 » Mon Mar 20, 2023 5:58 pm America/New_York

Hi there,

I want to convert the MOBY (in situ buoy data) water leaving radiance () to remote sensing reflectance.
The data can be seen on the website: https://www.star.nesdis.noaa.gov/socd/moby/filtered_spec/M272_2022052323d.txt.

The following is the information given in the text file.
" DscS 1: MOS Calibrated Wavelength (nm)
DscS 2: Water-Leaving Radiance Lw1, Lu1 and Kl1(Lu1-Lu2) (�W/cm�/sr/nm)
DscS 3: Water-Leaving Radiance Lw2, Lu1 and Kl2(Lu1-Lu3) (�W/cm�/sr/nm)
DscS 4: Water-Leaving Radiance Lw7, Lu2 and Kl3(Lu2-Lu3) (�W/cm�/sr/nm)
DscS 5: Surface Irradiance (�W/cm�/nm) for Lw1
DscS 6: Surface Irradiance (�W/cm�/nm) for Lw2
DscS 7: Surface Irradiance (�W/cm�/nm) for Lw7
DscS 8: Modeled KL: Water-Leaving Radiance Lw21, Lu1 and Kl21-m (�W/cm�/sr/nm)

Xdat:
lambda, Lw1, Lw2, Lw7, Ed Sfc, Ed Sfc, Ed Sfc, Lw21
343.8885, 1.158202, , , 78.828, 78.828, 81.033, 1.158202
344.4570, 0.824319, , , 68.706, 68.706, 71.467, 0.824319
-------------------------------"

Is there any way to convert the Lw values into Rrs (unit /Sr)? My plan is to compare the Hawaii time series Rrs (Sr^-1) (MOBY) with SeaHawk L2 Rrs (Sr^-1)?

Can I get the Rrs (Sr^-1) by the following equation?
Rrs = Lw1/Ed Sfc [As this is an insitu mesurement]

I found this site (https://seadas.gsfc.nasa.gov/help-8.2.0/rad2refl/Rad2ReflAlgorithmSpecification.html#:~:text=The%20conversion%20from%20TOA%20radiance,the%20inverse%20of%20this%20equation.) But, I am not sure if it is applicable for the buoy data.

Any help will be highly appreciated.

Best regards,
Masud

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OB General Science - guoqingw
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Re: Conversion of radiance to reflectance in MOBY data

by OB General Science - guoqingw » Tue Mar 21, 2023 12:06 pm America/New_York

Hi Masud,

I'm not very sure about NOAA data, but for the MOBY data provided through SeaBASS, here is a documentation with all the details: https://seabass.gsfc.nasa.gov/wiki/MOBY
Hope it helps.

Guoqing

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