500*2000 HICO image of Bahrain, oct 21rst 2013
scene iss.2013294.1021.093734.L1B.Bahrain.v04.14946.20131021200925.100m.hico courtesy of OSU
HICO: Hyperspectral Imager for the Coastal Ocean: GSD 100 m
work done march 2016

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Optical calibration

Calibration is outstanding

Kblue/Kbgreen=0.740

Kblue=0.130 m-1 , Kgreen=0.176 m-1

See that it is necessary to decrease markedly the operational attenuation coefficients in the Yellow-Red-NIR range

this is now recognised to be systematic, probably under control of the path radiance (overcast skies, here)

it is a remarkable feature of the diffuse underwater light field observed from above by a remote sensing imager

7=Blue

13=Green

22=Red

28=NIR

X[7]/X[13]: the ratio Kblue/Kgreen is well secured at K7/K13=0.74 over the whole depth range

X[7]/X[22]=0.280 and X[13]/X[22]=0.378 are fairly secure

280/378=0.741: this system is consistent

it actually is consistent over the whole visible range: this is remarkable

WL[7]=475 nm

WL[11]=522 nm

WL[20]=625 nm

Channel 27 is PANchromatic

X[7] vs X[27]: calibration of the PAN channel is under tight control