Bathymetry and water column correction
LANDSAT 8 OLIP 
at Whitsunday Island, GBR, Australia
  7711*7830, 30 m pixel size, UTM zone 55
scene LC80930742013178LGN01, June 27th 2013. Image courtesy of the U.S. Geological Survey
Work done november 2013
 
Using the Panchromatic band for water column correction
to derive water depth and spectral bottom signature:

Landsat 8 OLIP bandset used for this work
Purple=1Blue=2Green=3PAN=4Red=5NIR=6 and SWIR1=7
 

This is typically an image that is unsuitable for 4SM shallow water work


 
1 - NO NEED for field data, nor for atmospheric correction
2 - this is demonstrated in this website, using a variety of hyper/multi spectral data
 
Requirements are
1 - homogeneous water body and atmosphere
2 - some coverage of optically deep water
3 - some coverage of dry land
 
Problems are
1 - the precision on estimated depth is found wanting, because the noise-equivalent change in radiance  of accessible data is too high for shallow water column correction work 
2 - radiance data should be preprocessed by the provider at level 1 in order to improve S/N ratio
3 - exponential decay: the deeper/darker the bottom, the poorer the performances
 
So
I keep digging
until suitable data
become available
 


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

SWIR1

TCC
Landsat OLI exhibits excellent radiometric quality






But: see how system noise
is transferred from the NIR band
into other bands
upon deglinting

How sad!    ====>>>>

 






Deglinting

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

Glint regression based on NIR band

                            Deglinted TCC
  • The wildfire smoke is not removed by the deglinting process
  • Note the swirling plumes of turbid waters flowing through the Great Barrier reefs
 
This is typically an image that is unsuitable for 4SM shallow water work.
Although limited (and possibly usefull) results
shall be obtained by raising the operational thresholds at very high values.
 Deglinting along Profile Red
  • This scene has hardly any glint
  • Apart from the wildfire smoke at 30 km,
    • almost all variations are caused by swirling water trubidity