Retrieving Aerosol Characteristics From the PACE Mission, Part 1: Ocean Color Instrument

Remer, L. A.; Davis, Anthony B.; Mattoo, S.; Levy, Robert C.; Калашникова, О. В.; Coddington, O.; Chowdhary, Jacek; Knobelspiesse, Kirk; Xu, Xiaoguang; Ahmad, Ziauddin; Boss, Emmanuel; Cairns, Brian; Dierssen, Heidi M.; Diner, David J.; Franz, Bryan A.; Frouin, Robert; Gao, Bo; Ibrahim, Amir; Martins, J. V.; Omar, Ali; Torres, Omar; Xu, Feng; Zhai, Peng-Wang

doi:10.3389/feart.2019.00152

Cited by 40 publications

(27 citation statements)

References 130 publications

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“…One of the challenges of PACE will be the attempt to extract additional information from the ultraviolet (UV) wavelengths. The use of UV observations by the OCI radiometer for aerosol retrievals is addressed in this issue in a separate paper (Remer et al, 2019), but here we present a summary of the results of a theoretical sensitivity study (Zhai et al, 2017b) that highlights the importance of polarimetry to constrain the uncertainty introduced by the UV (Kahn et al, 2016). Note that we discuss these results from the perspective of aerosol characterization.…”

mentioning

confidence: 90%

“…The six wavelengths spanned the MODIS spectrum (0.55-2.13 µm). OCI, extending to hyperspectral and into the UV, should add information content to the MODIS-like measurements, and the possibility of using this information to retrieve absorption and aerosol layer height was explored in a companion paper (Remer et al, 2019). However, the most significant increase in information content (often expressed as Degrees of Freedom for Signal, DFS) can be made with multi-angle polarimetry, thus offering the potential for more complete, and accurate, aerosol characterization FIGURE 2 | Annual mean aerosol absorption properties for 2006 derived from PODER-3/PARASOL observations using the GRASP algorithm reporting single scattering albedo (SSA) at 670 nm (Top) and using the SRON retrieval algorithm (Hasekamp et al, 2011;Fu and Hasekamp, 2018) reporting absorbing aerosol optical depth (AAOD) at 550 nm (Bottom).…”

Section: Multi-angular Polarimetric Information Content For Aerosol Rmentioning

confidence: 99%

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Retrieving Aerosol Characteristics From the PACE Mission, Part 2: Multi-Angle and Polarimetry

Remer

Knobelspiesse

Zhai

et al. 2019

Front. Environ. Sci.

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The Plankton, Aerosol, Clouds, ocean Ecosystem (PACE) mission presents new opportunities and new challenges in applying observations of two complementary multi-angle polarimeters for the space-based retrieval of global aerosol properties. Aerosol remote sensing from multi-angle radiometric-only observations enables aerosol characterization to a greater degree than single-view radiometers, as demonstrated by nearly two decades of heritage instruments. Adding polarimetry to the multi-angle observations allows for the retrieval of aerosol optical depth, Angstrom exponent, parameters of size distribution, measures of aerosol absorption, complex refractive index and degree of non-sphericity of the particles, as demonstrated by two independent retrieval algorithms applied to the heritage POLarization and Directionality of the Earth's Reflectance (POLDER) instrument. The reason why this detailed particle characterization is possible is because a multi-angle polarimeter measurement contains twice the number of Degrees of Freedom of Signal (DFS) compared to an observation from a single-view radiometer. The challenges of making use of this information content involve separating surface signal from atmospheric signal, especially when the surface is optically complex and especially in the ultraviolet portion of the spectrum where we show the necessity of polarization in making that separation. The path forward is likely to involve joint retrievals that will simultaneously retrieve aerosol and surface properties, although advances will be required in radiative transfer modeling and in representing optically complex constituents in those models. Another challenge is in having the processing capability that can keep Remer et al. Aerosol Characterization With PACE Polarimeters pace with the output of these instruments in an operational environment. Yet, preliminary algorithms applied to airborne multi-angle polarimeter observations offer encouraging results that demonstrate the advantages of these instruments to retrieve aerosol layer height, particle single scattering albedo, size distribution and spectral optical depth, and also show the necessity of polarization measurements, not just multi-angle radiometric measurements, to achieve these results.

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confidence: 90%

Section: Multi-angular Polarimetric Information Content For Aerosol Rmentioning

confidence: 99%

Retrieving Aerosol Characteristics From the PACE Mission, Part 2: Multi-Angle and Polarimetry

Remer

Knobelspiesse

Zhai

et al. 2019

Front. Environ. Sci.

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“…Estimation of the ocean color signal from the total at-sensor space-borne or air-borne measurement is known as atmospheric correction, which removes the radiometric contributions of the atmosphere and ocean surface (Wang, 2010;Mobley et al, 2016). Quantifying the effect of atmospheric aerosols is a primary challenge in the atmospheric correction , due to their diversity of size, composition, and morphology, and associated variability in absorption and scattering properties (Remer et al, 2019a).…”

Section: Introductionmentioning

confidence: 99%

“…Through the combination of OCI and the two MAPs, the PACE mission provides a novel opportunity to bridge polarimetric and hyperspectral observations and advance the retrieval of both aerosol and ocean properties (Remer et al, 2019a, b;Chowdhary et al, 2019). Near infrared (NIR) or SWIR bands are often used to derive aerosol properties over ocean waters, and that approach has been implemented for the Hyperspectral Imager for the Coastal Ocean (HICO) (Ibrahim et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Inversion of multi-angular polarimetric measurements from the ACEPOL campaign: an application of improving aerosol property and hyperspectral ocean color retrievals

Meng¹,

Zhai²,

Franz³

et al. 2020

Preprint

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Abstract. NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, scheduled for launch in the timeframe of late 2022 to early 2023, will carry the Ocean Color Instrument (OCI), a hyperspectral scanning radiometer, and two multi-angle polarimeters (MAP), the UMBC Hyper-Angular Rainbow Polarimeter (HARP2) and the SRON Spectro-Polarimeter for Planetary EXploration one (SPEXone). One purpose of the PACE MAPs is to better characterize aerosols properties, which can then be used to improve atmospheric correction for the retrieval of ocean color in coastal waters. Though this is theoretically promising, the use of MAP data in the atmospheric correction of collocated hyperspectral ocean color measurements has not yet been well demonstrated. In this work, we performed aerosol retrievals using the MAP measurements from the Research Scanning Polarimeter (RSP), and demonstrate its application to the atmospheric correction of hyperspectral radiometric measurements from SPEX Airborne. Both measurements were collected on the same aircraft from the Aerosol Characterization from Polarimeter and Lidar (ACEPOL) field campaign in 2017. Two cases over ocean with small aerosol loading (aerosol optical depth ∼ 0.04) are identified including collocated RSP and SPEX Airborne measurements and Aerosol Robotic Network (AERONET) in-situ observations. The aerosol retrievals are performed and compared with two options: one uses reflectance only and the other use both reflectance and polarization. It is demonstrated that polarization information helps reduce the uncertainties of aerosol microphysical and optical properties. The retrieved aerosol properties are then used to compute the contribution of atmosphere and ocean surface for atmospheric correction over the discrete bands from RSP measurements and the hyperspectral SPEX Airborne measurements. The water leaving signals determined this way are compared with both AERONET and Moderate Resolution Imaging Spectroradiometer (MODIS) Ocean Color products with good agreement. The results and lessons-learned from this work will provide a basis to fully exploit the information from the unique combination of sensors on PACE for aerosol characterization and ocean ecosystem research.

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“…Advancements have also been made in aerosol height retrievals from OCI-like passive remote sensing data [e.g., Duforêt et al (2007) and Dubuisson et al (2009) from POLDER and MERIS (Medium Resolution Imaging Spectrometer) data]. Sensitivity studies on the information content of aerosol height over oceans in OCI's hyperspectral measurements of Oxygen Aand B-band radiance are reported by Davis and Kalashnikova (2019), Frouin et al (2019), and Remer et al (2019). In addition, studied aerosol height retrievals over vegetated land from actual Oxygen B-band radiance measured by the EPIC (Earth Polychromatic Imaging Camera) instrument onboard the DSCOVR (Deep Space Climate Observatory) platform.…”

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Modeling Atmosphere-Ocean Radiative Transfer: A PACE Mission Perspective

et al. 2019

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The research frontiers of radiative transfer (RT) in coupled atmosphere-ocean systems are explored to enable new science and specifically to support the upcoming Plankton, Aerosol, Cloud ocean Ecosystem (PACE) satellite mission. Given (i) the multitude of atmospheric and oceanic constituents at any given moment that each exhibits a large variety of physical and chemical properties and (ii) the diversity of light-matter interactions (scattering, absorption, and emission), tackling all outstanding RT aspects related to interpreting and/or simulating light reflected by atmosphere-ocean systems becomes impossible. Instead, we focus on both theoretical and experimental studies of RT topics important to the science threshold and goal questions of the PACE mission and the measurement capabilities of its instruments. We differentiate between (a) forward (FWD) RT studies that focus mainly on sensitivity to influencing variables and/or simulating data sets, and (b) inverse (INV) RT studies that also involve the retrieval of atmosphere and ocean parameters. Our topics cover (1) the ocean (i.e., water body): absorption and elastic/inelastic scattering by pure water (FWD RT) and models for scattering and absorption by particulates (FWD RT and INV RT); (2) the airwater interface: variations in ocean surface refractive index (INV RT) and in whitecap reflectance (INV RT); (3) the atmosphere: polarimetric and/or hyperspectral remote sensing of aerosols (INV RT) and of gases (FWD RT); and (4) atmosphere-ocean systems: benchmark comparisons, impact of the Earth's sphericity and adjacency effects on space-borne observations, and scattering in the ultraviolet regime (FWD RT). We provide for each topic a summary of past relevant (heritage) work, followed by a discussion (for unresolved questions) and RT updates.

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Retrieving Aerosol Characteristics From the PACE Mission, Part 1: Ocean Color Instrument

Cited by 40 publications

References 130 publications

Retrieving Aerosol Characteristics From the PACE Mission, Part 2: Multi-Angle and Polarimetry

Retrieving Aerosol Characteristics From the PACE Mission, Part 2: Multi-Angle and Polarimetry

Inversion of multi-angular polarimetric measurements from the ACEPOL campaign: an application of improving aerosol property and hyperspectral ocean color retrievals

Modeling Atmosphere-Ocean Radiative Transfer: A PACE Mission Perspective

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