Stripe lines problem when applying SWIR atmospheric correction

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Topic SeaDAS / SeaDAS 6.x - General Questions / Stripe lines problem when applying SWIR atmospheric correction (locked) (3109 hits)

By eko Date 2010-02-11 13:53 Edited 2010-02-11 14:04

Hi,

I processed MODIS high resolution (500 meter) Chl-a by applying SWIR atmospheric correction with script as attached.
I found some problems as follows.

1) There are many stripe horizontal lines as in attached fig.b.
But, I did not find such a problem when standard atmospheric correction was appilied (fig.a)
2) The Chl-a images processed by SWIR atmocor (fig. b) was also not as smooth as that by standard atmocor (fig.a)
3) Some data were also missing near the coast when applying SWIR atmocor.

Parameter file created during processing from level 1B_LAC to Level 2 is also attached.
I am using SeaDAS 6 on Fedora 10.

Can anyone show me the problem and how to resolve it?
Thank you.

Eko

Attachment: l1b_to_l2_script.csh (0.5k)

Attachment: A2009240040500.L2.par (2.5k)

By @sean Date 2010-02-12 19:08

Eko,

The banding you see is the result of a bad detector in the 1240nm band.
With collection 5, the bad detector was replaced with a value that was
interpolated from neighboring detectors. With collection 6, this interpolation
is no longer done, so the bad detector shows up as an atmospheric correction
failure - and thus banding in the L2.

There currently is no resolution to this problem - other than reverting back to
the collection 5 processing (which was distributed with the previous version
of SeaDAS).

As you saw, the problem does not exist for high res processing using the NIR
bands, since this does not use the 1240nm band.

Regards,
Sean

By eko Date 2010-02-16 01:52

Sean,

Since with version of SeaDAS the interpolation from neighboring detectors has been no longer done?
Is SeaDAS 5.4 also released with collection 5 processing?

Thank you.

Eko

By @sean Date 2010-02-16 02:03

"Collection" is a term used by the MODIS program. We use the official
L1B code (with very minor changes), which changes on a different
reprocessing (or collection) schedule than our ocean color reprocessing
schedule. The current MODIS "collection" is 5, with Collection 6
nearing readiness. We received the Collection 6 code and L1B LUTs
from the MODIS program to allow us to use them with our reprocessing
which will be the first MODIS discipline to use it. Prior to SeaDAS 6.0,
our MODIS processing used Collection 5 code and L1B LUTs.

It is with collection 6 that the interpolation was dropped.

Sean

Topic SeaDAS / SeaDAS 6.x - General Questions / Stripe lines problem when applying SWIR atmospheric correction (locked) (3109 hits)