Atmospheric correction -2/-9

vbsbalanin · by **vbsbalanin** » Wed May 10, 2017 12:13 pm America/New_York

Hi
I just want to know whether the aer_opt = -9 option also follows the iteration technique (Bailey, 2010) as like aer_opt = -2 irrespective of band combinations.
Can anyone help me in this regard.

Thanks
Sundarabalan

OB.DAACx - SeanBailey · by **OB.DAACx - SeanBailey** » Wed May 10, 2017 8:04 pm America/New_York

Yes, but only when the NIR bands are used for the aerosol selection. If the SWIR bands are chosen, the Bailey et. al. 2010 iteration scheme is not applied.

Sean

vbsbalanin · by **vbsbalanin** » Thu May 11, 2017 4:22 am America/New_York

Thanks Sean.

Also can you please tell
The aer_opt = -2 (Bailey et. al. 2010) works differently for turbid waters and clear waters. Is it correct?
Because I processed one coastal image. In that some pixels near to the coastal area the l2_flags.TURBIDW is true.

Thanks
Sundarabalan

OB.DAACx - SeanBailey · by **OB.DAACx - SeanBailey** » Thu May 11, 2017 12:24 pm America/New_York

The paper explains the conditions where it is applied: "It should also be noted that the Rrs (NIR) is forced to zero if the initial iteration results in a C_a < 0.3 mg m^-3 . This is done to avoid the addition of noise into clear-water pixels through the estimation of otherwise negligible Rrs (NIR) contributions."
Clear water chlorophyll concentrations are typically less than 0.3 and so the NIR iteration moves on, effectively doing nothing.

Sean

vbsbalanin · by **vbsbalanin** » Thu May 11, 2017 12:58 pm America/New_York

Got it Sean. Thanks for the detailed information.

Sundarabalan