Takapoto atoll,

Tuamotu archipelago, French Polynesia

 
 
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 Spot 1991
Landsat 8 december 16th 2020
 

 

A 740*940 SPOT-1 image of Takapoto atoll 1991
work done in 2005

An excellent image, in spite of marked skyglint.
Nice and easy calibration.
Jerlov water type OIB+0.35: very clear.
Maximum penetration of XS1 in excess of 30 m over bright coral sandy bottoms in lagoon waters. 
Average bottom brightness Retrieved depth 

 

 GREEN: sea truth depth sounding lines

RED: retrieved depths 
GPS positioning can be poor
 


 



Landsat 8 december 16th 2020 over Takapoto and Takaroa atolls
this image is not suitable for 4SM work
 


TCC deglinted Red, Pan, Ublue (RGB)
  • Please note green tones inside the lagoons of both atolls,
    • where bottom depth should mostly be opticaly deep, exceeding 38 m  
  • This denotes a greenish deep water reflectance, very low in the UlBlue band.
  • This hints at weird water optical properties
    • that markedly depart from Jerlov's familly of curves 
    • this image is not suitable for 4SM work
  

Calibration Blue, Green, Red, Nir
over the two atolls
   



 work in progress










 


 




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