Loisel and Stramski algorithm application to other sensors

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Loisel and Stramski algorithm application to other sensors

by tihicha » Mon Jan 27, 2020 6:39 pm America/New_York

Regarding the Loisel and Stramski IOP code as implemented in SeaADS:

I was wondering what your approach is to apply the algorithm to sensors other than SeaWiFS, as the original code coefficients are provided for SeaWiFS only. The Loisel code as posted here (https://www.ioccg.org/groups/Software_OCA/IOP_inversion.f) is specified at 410, 440 , 490, 510 and 550 nm. Is anything done, and does anything need to be done to apply it even to SeaWiFS, which has slightly different center wavelengths, notably 555 instead of 550 nm.

I know this is asking about code that is quite old by now. Thanks very much for your time looking into it!


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Loisel and Stramski algorithm application to other sensors

by OB.DAAC - SeanBailey » Tue Jan 28, 2020 6:30 pm America/New_York


Generally, if code requires a specific set of wavelengths, l2gen will generalize by picking the closest wavelength (to a point).
For example:

  302         wave = l1rec->l1file->fwave;
  303         ib443 = windex(443, wave, nbands);
  304         ib555 = windex(555, wave, nbands);

The windex function finds the sensor wavelength closest to the requested value.

In the case of the LAS code you reference, it  gives another clue as to how it specifically handles the table:

  161         // if the input wavelength is not one of the table wavelengths, call the
  162         // function recursively for bounding table wavelengths and interpolate

Hope this helps.

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