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Validation of a spectral correction procedure for sun and sky reflections in above-water reflectance measurements

Groetsch, Philipp M. M. and Gege, Peter and Simis, Stefan G. H. and Eleveld, Marieke A. and Peters, Steef (2017) Validation of a spectral correction procedure for sun and sky reflections in above-water reflectance measurements. Optics Express, 25 (16), A742-A761. Optical Society of America. DOI: 10.1364/OE.25.00A742 ISSN 1094-4087

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Official URL: https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-16-A742


A three-component reflectance model (3C) is applied to above-water radiometric measurements to derive remote-sensing reflectance Rrs(l). 3C provides a spectrally resolved offset D(l) to correct for residual sun and sky radiance (Rayleigh- and aerosol-scattered) reflections on the water surface that were not represented by sky radiance measurements. 3C is validated with a data set of matching above- and below-water radiometric measurements collected in the Baltic Sea, and compared against a scalar offset correction D. Correction with D(l) instead of D consistently reduced the (mean normalized root-mean-square) deviation between Rrs(l) and reference reflectances to comparable levels for clear (D: 14.3 +- 2.5 %, D(l): 8.2 +- 1.7 %), partly clouded (D: 15.4 +- 2.1 %, D(l): 6.5 +- 1.4 %), and completely overcast (D: 10.8 +- 1.7 %, D(l): 6.3 +- 1.8 %) sky conditions. The improvement was most pronounced under inhomogeneous sky conditions when measurements of sky radiance tend to be less representative of surface-reflected radiance.Accounting for both sun glint and sky reflections also relaxes constraints on measurement geometry, which was demonstrated based on a semi-continuous daytime data set recorded in an eutrophic freshwater lake in the Netherlands. Rrs(l) that were derived throughout the day varied spectrally by less than 2 % relative standard deviation. Implications on measurement protocols are discussed. An open source software library for processing reflectance measurements was developed and is made publicly available.

Item URL in elib:https://elib.dlr.de/113967/
Document Type:Article
Title:Validation of a spectral correction procedure for sun and sky reflections in above-water reflectance measurements
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Groetsch, Philipp M. M.groetsch (at) waterinsight.nlUNSPECIFIED
Gege, Peterpeter.gege (at) dlr.dehttps://orcid.org/0000-0003-0939-5267
Simis, Stefan G. H.Plymouth Marine LaboratoryUNSPECIFIED
Eleveld, Marieke A.Vrije Universiteit AmsterdamUNSPECIFIED
Peters, Steefwater insight bv, the netherlandsUNSPECIFIED
Date:7 August 2017
Journal or Publication Title:Optics Express
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
DOI :10.1364/OE.25.00A742
Page Range:A742-A761
Publisher:Optical Society of America
Keywords:Remote sensing and sensors; Surface waves; Reflection; Water; Oceanic optics; Aerosols; Clouds
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):Vorhaben Spectroscopic Methods in Remote Sensing
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Experimental Methods
Deposited By: Gege, Dr.rer.nat. Peter
Deposited On:13 Sep 2017 13:18
Last Modified:15 Jan 2019 11:30

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