4SM OLI andros bahamas

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The data
Deglinting
Optical calibration
Results

The data
Seven bands are used: Purple, Blue, Green, PAN, Red, NIR and SWIR1

Panchromatic band, sum-aggregated to 30 m, exhibits excellent radiometric quality	TCC Landsat OLI exhibits excellent radiometric quality
SWIR1 The atmosphere in this image is very thick

Deglinting

Glint regression based on SWIR1 band
SWIR1 is quite convenient for deglinting

Glint regression based on NIR band

Deglinted TCC

Please note the distinct negative bopttom contrast between waypoints 2 and 3 along Red Profile
With La_swir1 =Lsw_swir1 at ~10 under the cloud shadows, it is seen that the atmosphere in this scene exhibits a lot of aerosols

Deglinting of
PURPLE and SWIR1 bands

along Profile Red

Please note the pronounced and steady increase of the signal in the SWIR1 band from West to East: "deglinting" removes it efficiently
The atmospheric path radiance is set at 17 in the SWIR1 band: this is observed under could shadows, while the lowest sea-surface signal under sun illumination is 10 DNs stronger.
- this must be accomodated in the optical calibration!
The negative bottom contrast in the Purple band is quite pronounced between waypoints 2 and 3 along Red Profile

Optical calibration:
Water type OIB of Jerlov
Spectral reflectance of the brightest bottoms:
0.390 0.470 0.527 0.541 0.589 0.690 0.290
on the scale 0-1, as calibrated using the _MTL.txt textfile

Calibration diagram
for bands Blue, Green, Red and NIR

Calibration diagram
for bands Blue, Green, Pan and Red

Operational wavelengths

Here again

the wavelength for the Red band must be set at a very low value: WL_red=600 nm
the wavelength for the Purple band must be set at a very high value: WL_purple=470 nm
the wavelength for the Blue and Green bands are set at mid-waveband

The use of Hydrolight code should provide an insight into this question.

Operational wavelengths

I suspect that this is all-important aspect (for a "NoNeed or field data" method) very much depends on the bi-directional properties of the light field
- because stuffy atmospheres deliver very high levels of very diffuse illumination
- this is most often the case in the Gulf of Arabs (Emirates)
As a result, very low diffuse attenuation coefficients are observed under very high levels of very diffuse illumination (whitish skyes), while Jerlov's diffuse attenuation data assume clear dep-blue skies
As a consequence, under such illumination conditions, record shallow water penetrations are observed, which exceed by large the perfomance we can expect from using Jerlov's data.