PosterPDF Available

Validation of the Operational Land Imager orange contra-band retrieval for inland water quality applications



This poster presents the results of a validation study on the calculated orange contra-band (613 nm) for OLI/Landsat 8 against the orange band (620 nm) of OLCI/Sentinel-3. The approach forces atmospheric compensation (AC) bias to be equal for each sensor and scene, allowing to compare the retrieved water leaving signal directly. We find that OLI orange contra-band has the expected relation to OLCI/Sentinel-3 as observed with in situ data for all studied lakes, except one. This further evidence that the contra-band algorithm has a solid analytical foundation and is robust to sensor noise and AC impact on the OLI input bands. Final peer-review study available here:
Expectation from in situ data: slope between 0.85
and 1, depending on the presence of phycocyanin.
Validation of the Operational Land Imager orange contra-band
retrieval for inland water quality applications
Matchups with OLCI/Sentinel-3
Alexandre Castagna, Stefan Simis, Heidi Dierssen, Quinten Vanhellemont, Koen Sabbe, Wim Vyverman
A m e t h o d i s n o w a v a i l a b l e t o extract
a d d i t i o n a l s p e c t r a l i n f o r m a t i o n f r o m
overlapping wavebands (Castagna et al.,
2018). When applied to OLI/Landsat 8, an
o r a n g e c o n t r a - b a n d ( 6 1 3 n m ) c a n b e
retrieved from the Green, Red and Pan
b a n d s . T h i s c o n t r a - b a n d c o v e r s t h e
phycocyanin absorption peak and can be
used for cyanobacteria detection at high
spatial resolution. Here we further evaluate
its performance with comparison against
OLCI/Sentinel-3 orange band (620 nm),
taken as a calibrated reference. The goal is
to validate the absolute magnitude of the
orange contra-band.
C a s t a g n a e t a l . , 2 0 1 8 , E x t e n d i n g t h e
O p e r a t i o n a l L a n d I m a g e r / L a n d s a t 8 f o r
freshwater research: retrieval of an orange
band from PAN and MS bands. Ocean Optics
XXIV, Dubrovinik, Croatia.
Example application
Floating vegetation
Validation approach
Embalse Cerron Grande, SV, 2018-09-06
To compare the absolute reflectance magnitude
be tw ee n OL I and OLCI it i s n ec es s ar y tha t
at m os p her ic e ff e ct s a re rem o ved and any
residual atmospheric bias be equal for both
sensors. Compensation for atmosphere effects is
challenging over turbid inland waters in the
absence of SWIR bands, therefore OLI processed
with ACOLITE was taken as reference in the
multispectral bands other than the orange. OLCI
imagery was first partially compensated for
Rayleigh effects only with SeaDAS and then
subtracted by the median difference to OLI
multispectral bands. The OLCI orange band (620
nm) was corrected with the interpolated median
difference between Green and Red bands. Spatial
aggregation and bandshifting was performed
before the correction.
80 matchups between OLI and OLCI were
processed, covering 10 lakes between 2016
and 2019.
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