Particulate Backscattering in the Global Ocean: A Comparison of Independent Assessments

Bisson, Kelsey; Boss, Emmanuel; Werdell, P. Jeremy; Ibrahim, Amir; Behrenfeld, Michael J.

doi:10.1029/2020gl090909

Cited by 43 publications

(40 citation statements)

References 34 publications

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“…The relative error ( Measuredvalue−Truevalue Truevalue × 100%) of the measured attenuated backscatter coefficient from perpendicular channel (β s,measured , km −1 sr −1 ) and total depolarization ratio (δ t,measured ) due to the crosstalk are~50%. The particulate backscattering coefficient (b bp , m −1 ) at 532 nm can be estimated as [5,10]:…”

Section: Effects Of Crosstalk On Measured Ocean Backscattered Signalsmentioning

confidence: 99%

“…The relative differences of the retrieved crosstalk by the two methods and between the two chosen regions are less than 10%. Therefore, the crosstalk-corrected attenuated backscatter coefficients can be derived from the measured signals in a straightforward manner, as indicated in Equations ( 9) and (10). The correction method is suitable for the global ocean including regions with low-nutrient and low-biomass waters (e.g., Figures 5 and 6).…”

Section: Effects Of Crosstalk On Measured Ocean Backscattered Signalsmentioning

confidence: 99%

“…Although CALIOP was not designed for ocean subsurface applications, its measurements over the Earth's oceans now provide a wealth of unanticipated opportunities for ocean biology and biogeochemistry studies. During the past decade, innovative retrieval methods have been developed to translate CALIOP's ocean backscattered signals into ocean optical properties such as global phytoplankton distributions [5], total particulate organic carbon (POC) stocks [5,6], particulate backscattering coefficients (b bp , m −1 ) [7][8][9][10], phytoplankton biomass estimates [11], and depolarization ratios of ocean waters [12][13][14]. These breakthroughs have demonstrated that the satellite lidar era in the oceanography has arrived [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, estimates of ocean optical properties derived from CALIOP measurements must take crosstalk into account and the crosstalk artifacts should be removed before retrieving ocean optical properties. Previous CALIOP ocean studies [5,10,11] with crosstalk properly handled should not be questioned. Unfortunately, previous analyses of CALIOP data for ocean studies [7,12,13] ignored the effect of optical crosstalk between the 532 nm parallel and perpendicular channels will have relatively high crosstalk induced errors.…”

Section: Introductionmentioning

confidence: 99%

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Global Ocean Studies from CALIOP/CALIPSO by Removing Polarization Crosstalk Effects

Omar

et al. 2021

Remote Sensing

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Recent studies indicate that the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite provides valuable information about ocean phytoplankton distributions. CALIOP’s attenuated backscatter coefficients, measured at 532 nm in receiver channels oriented parallel and perpendicular to the laser’s linear polarization plane, are significantly improved in the Version 4 data product. However, due to non-ideal instrument effects, a small fraction of the backscattered optical power polarized parallel to the receiver polarization reference plane is misdirected into the perpendicular channel, and vice versa. This effect, known as polarization crosstalk, typically causes the measured perpendicular signal to be higher than its true value and the measured parallel signal to be lower than its true value. Therefore, the ocean optical properties derived directly from CALIOP’s measured signals will be biased if the polarization crosstalk effect is not taken into account. This paper presents methods that can be used to estimate the CALIOP crosstalk effects from on-orbit measurements. The global ocean depolarization ratios calculated both before and after removing the crosstalk effects are compared. Using CALIOP crosstalk-corrected signals is highly recommended for all ocean subsurface studies.

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Section: Effects Of Crosstalk On Measured Ocean Backscattered Signalsmentioning

confidence: 99%

Section: Effects Of Crosstalk On Measured Ocean Backscattered Signalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Global Ocean Studies from CALIOP/CALIPSO by Removing Polarization Crosstalk Effects

Omar

et al. 2021

Remote Sensing

View full text Add to dashboard Cite

show abstract

“…Consequently, estimates of ocean optical properties derived from CALIOP measurements must take crosstalk into account and the crosstalk artifacts should be removed before retrieving ocean optical properties. Unfortunately, previous analyses of CALIOP data for ocean studies [5,7,10,11,15] did not take into account the effect of optical crosstalk between the 532 nm parallel and perpendicular channels.…”

Section: Introductionmentioning

confidence: 99%

Global Ocean Studies from CALIOP/CALIPSO by Removing Polarization Crosstalk Effects

Lu¹,

Hu²,

Omar³

et al. 2021

Preprint

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The influence of particle concentration and bulk characteristics on polarized oceanographic lidar measurements

Collister

Zimmerman

Sukenik

et al. 2022

Limnology & Oceanography

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Oceanographic lidar measurements of the linear depolarization ratio, δ, contain information on the bulk characteristics of marine particles that could improve our ability to study ocean biogeochemistry. However, a scarcity of information on the polarized light‐scattering properties of marine particles and the lack of a framework for separating single and multiple scattering effects on δ have hindered the development of polarization‐based retrievals of bulk particle properties. To address these knowledge gaps, we made single scattering measurements of δ for several compositionally and morphologically distinct marine particle assemblages. We then used a bio‐optical model to explore the influence of multiple scattering and particle characteristics on lidar measurements of δ made during an expedition to sample a mesoscale coccolithophore bloom. Laboratory measurements of linear depolarization revealed a complex dependency on particle shape, size, and composition that were consistent with scattering simulations for idealized nonspherical particles. Model results suggested that the variability in δ measured during the field expedition was driven predominantly by shifts in particle concentration rather than their bulk characteristics. However, model estimates of δ improved when calcite particles were represented by a distinct particle class, highlighting the influence of bulk particle properties on δ. To advance polarized lidar retrievals of bulk particle properties and to constrain the uncertainty in satellite lidar retrievals of particulate backscattering, these results point to the need for future efforts to characterize the variability of particulate depolarization in the ocean and to quantify the sensitivity of operational ocean lidar systems to multiple scattering.

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Particulate Backscattering in the Global Ocean: A Comparison of Independent Assessments

Abstract: The spectral particulate backscattering coefficient (b bp ; m −1 ; with spectral dependence hereafter implied unless noted) is central to applications of ocean optics for marine ecology and biogeochemistry. Satellite-derived b bp has been used to assess particulate organic carbon (

Cited by 43 publications

References 34 publications

Global Ocean Studies from CALIOP/CALIPSO by Removing Polarization Crosstalk Effects

Global Ocean Studies from CALIOP/CALIPSO by Removing Polarization Crosstalk Effects

Global Ocean Studies from CALIOP/CALIPSO by Removing Polarization Crosstalk Effects

The influence of particle concentration and bulk characteristics on polarized oceanographic lidar measurements

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