LANDSAT 8 OLIP 
A time series of Landsat 8 OLIP images
at Nosy Be, Madagascar

work done in may 2020 at 15 m GSD
 
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

   peer-reviewed and published in 2017    

home
 
 
 
 
home
image aquired October 11th 2019
The data

TCC
notice the presence of and scattered clouds
and a thick layer of haze
 

TCC
some white caps are observed over open waters
   
   

Deglinting
TCC raw

Deglinting is excellent, but noisy
 
Glint is strong
 actually, it is caused by haze 
glint regressions are very good
 


Optical calibration

Calibration Blue, Green, Red and NIR
no stratification is observed

Calibration Blue, Green, PAN, and NIR
 
Hardly any stratification is observed
0-29 m Oceanic II+0.3 water type of Jerlov
 

 
X2,3 vs X5
Notice that a very good fit 
of the blue/red and green/red 
pairs of bands
distinctly requires 
that Kred be decreased
 
X2,3 vs X5
  • This is obtained here by setting CoefK=1.0 for the Red band
  • This might be related to the very diffuse downwelling light flux caused by the haze and scattered clouds

Results

Computed depth in centimeters


 

image WZ
  • The PAN solution only reaches down to max 11 m
  • The Green solution reaches down to ~20 m 

image B: bottom brightness
This actually shows bottom brightness in the Blue band 

image WCC
UltraBlue, Green, and Blue (BGR)

Color composite of water column corrected reflectances
   
 
Profiling


Radiances along Profile Blue
  • Radiances tend to increase eastward, as haze becomes thicker (or is it real glint?), and waters become choppy
  • Deglinting is quite efficient, although quite noisy
    •  smoothing shall be necessary


 


Location of profiles
Lsw radiance is sampled from the small blue rectangle


Modeling along Profile_red
Please note the prominent variations of the spectral bottom signature for the UltraBlue, Blue and Green bands


Green solution versus PAN solution
still needs minor adjustment
   
 



Créer un site
Créer un site