Abstract

We present a closure experiment between new inherent optical properties (IOPs: absorption a, scattering b, backscattering bb) and apparent optical properties (AOPs: remote-sensing reflectance Rrs, irradiance reflectance R, and anisotropic factor at nadir Qn) data of Ionian and Adriatic seawaters, from very clear to turbid waters, ranging across one order of magnitude in Rrs. The internal consistency of the IOP–AOP matchups was investigated though radiative transfer closure. Using the in situ IOPs, we predicted the AOPs with the commercial radiative transfer solver Hydrolight. Closure was limited by two unresolved issues, one regarding processing of in situ data and the other related to radiative transfer modeling. First, different correction methods of the absorption data measured by the Wetlabs ac-s produced high variations in simulated reflectances, reaching 40% for the highest reflectances in our dataset. Second, the lack of detailed volume scattering function measurements forces us to adopt analytical functions that are consistent with a given particle backscattering ratio. The analytical phase functions named Fournier-Forand and two-term Kopelevich presented reasonable angular shapes with respect to measurements at a few backward angles. Between these phase functions, induced changes were within 4% for Rrs, within 11% for R, and within 10% for Qn. Additionally, closure of Qn was generally not successful considering radiometric uncertainties. Simulated Qn overestimated low values and underestimated high values, especially at 665 nm, where Hydrolight was unable to predict measured Qn values greater than 6 sr. The physical nature of Qn makes this mismatch almost independent of the measured IOPs, thus precluding Qn tuning by varying the former. The non-closure of Qn might be caused by an inaccurate phase function and, to a lesser extent, by the modeling of the incoming radiance. For the future, this remains the task of accurate absorption and phase function measurements, especially at red wavelengths.

© 2016 Optical Society of America

Full Article  |  PDF Article
OSA Recommended Articles
Closure and uncertainty assessment for ocean color reflectance using measured volume scattering functions and reflective tube absorption coefficients with novel correction for scattering

Alberto Tonizzo, Michael Twardowski, Scott McLean, Ken Voss, Marlon Lewis, and Charles Trees
Appl. Opt. 56(1) 130-146 (2017)

An inherent-optical-property-centered approach to correct the angular effects in water-leaving radiance

Zhong Ping Lee, Keping Du, Kenneth J. Voss, Giuseppe Zibordi, Bertrand Lubac, Robert Arnone, and Alan Weidemann
Appl. Opt. 50(19) 3155-3167 (2011)

Re-examining the effect of particle phase functions on the remote-sensing reflectance

Yuanheng Xiong, Xiaodong Zhang, Shuangyan He, and Deric J. Gray
Appl. Opt. 56(24) 6881-6888 (2017)

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Figures (10)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Tables (13)

You do not have subscription access to this journal. Article tables are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Equations (39)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Metrics

You do not have subscription access to this journal. Article level metrics are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription