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by axxs » Wed Apr 06, 2022 11:41 pm America/New_York
The value of a should be greater than the absorption by pure sea water of aw = 0.0448, why are most of the values measured by modis less than 0.0448? In addition, the absorption calculated by the chlorophyll concentration measured by modis does not quite match the absorption measured by modis itself.
There is a known bug in the processing of the IOP products related to the pure water values for aw and bbw. The current operational code uses an ASCII table of values that was updated prior to the last reprocessing. In that update, the header records for that file had a blank line and a couple of erroneously uncommented lines. The reader wasn't properly accounting for these and so the table was read in shifted by 3nm. Just 3nm, but that has an impact on the calculation of the integrated aw and bbw values. The result...in clear waters, the calculated aw is often less than the correct pure water value. This has been fixed and the products will reflect this with the upcoming reprocessing, which for Aqua-MODIS is expected to be done this May.