Expected performance and error analysis for SPEXone, a multi-angle channeled spectropolarimeter for the NASA PACE mission

Rietjens, Jeroen; Campo, Jochen; Chanumolu, Anantha; Smit, Martijn; Nalla, Raj; Fernandez, Cristina V.; Dingjan, Jos; Amerongen, Aaldert van; Hasekamp, Otto

doi:10.1117/12.2530729

Cited by 17 publications

(18 citation statements)

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“…The retrieval algorithm minimizes the difference between the MAP measurements and the forward model simulations computed from vector radiative transfer simulations (Zhai et al, 2009(Zhai et al, , 2010. By assuming the measurement and modeling uncertainties follow Gaussian statistical distributions, the retrieval parameters can be estimated through Bayesian theory using the cost function χ 2 to quantify the difference between the measurement and the forward model simulation (Rogers, 2000):…”

Section: Joint Aerosol and Ocean Color Retrieval Algorithmmentioning

confidence: 99%

“…OCI will provide continuous spectral measurements from the ultraviolet (340 nm) to near-infrared (890 nm) with full width at half maximum of 5 nm resolution and sampling every 2.5 nm, plus a set of seven discrete shortwave infrared (SWIR) bands centered at 940, 1038, 1250, 1378, 1615, 2130, and 2260 nm. SPEXone performs multi-angle measurements at five along-track viewing angles of 0 • , ±20 • , and ±58 • , with a surface swath of 100 km and a continuous spectral range spanning 385-770 nm at resolutions of 2-3 nm for intensity and 10-40 nm for polarization (Rietjens et al, 2019). HARP2 is a wide field-of-view imager that measures the polarized radiances at 440, 550, 670, and 870 nm, where the 670 nm band will measure 60 viewing angles and the other bands 10 viewing angles, with a swath of 1556 km at nadir on the Earth's surface.…”

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confidence: 99%

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Efficient multi-angle polarimetric inversion of aerosols and ocean color powered by a deep neural network forward model

et al. 2021

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Abstract. NASA's Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, scheduled for launch in the timeframe of 2023, will carry a hyperspectral scanning radiometer named the Ocean Color Instrument (OCI) and two multi-angle polarimeters (MAPs): the UMBC Hyper-Angular Rainbow Polarimeter (HARP2) and the SRON Spectro-Polarimeter for Planetary EXploration one (SPEXone). The MAP measurements contain rich information on the microphysical properties of aerosols and hydrosols and therefore can be used to retrieve accurate aerosol properties for complex atmosphere and ocean systems. Most polarimetric aerosol retrieval algorithms utilize vector radiative transfer models iteratively in an optimization approach, which leads to high computational costs that limit their usage in the operational processing of large data volumes acquired by the MAP imagers. In this work, we propose a deep neural network (NN) forward model to represent the radiative transfer simulation of coupled atmosphere and ocean systems for applications to the HARP2 instrument and its predecessors. Through the evaluation of synthetic datasets for AirHARP (airborne version of HARP2), the NN model achieves a numerical accuracy smaller than the instrument uncertainties, with a running time of 0.01 s in a single CPU core or 1 ms in a GPU. Using the NN as a forward model, we built an efficient joint aerosol and ocean color retrieval algorithm called FastMAPOL, evolved from the well-validated Multi-Angular Polarimetric Ocean coLor (MAPOL) algorithm. Retrievals of aerosol properties and water-leaving signals were conducted on both the synthetic data and the AirHARP field measurements from the Aerosol Characterization from Polarimeter and Lidar (ACEPOL) campaign in 2017. From the validation with the synthetic data and the collocated High Spectral Resolution Lidar (HSRL) aerosol products, we demonstrated that the aerosol microphysical properties and water-leaving signals can be retrieved efficiently and within acceptable error. Comparing to the retrieval speed using a conventional radiative transfer forward model, the computational acceleration is 103 times faster with CPU or 104 times with GPU processors. The FastMAPOL algorithm can be used to operationally process the large volume of polarimetric data acquired by PACE and other future Earth-observing satellite missions with similar capabilities.

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Section: Joint Aerosol and Ocean Color Retrieval Algorithmmentioning

confidence: 99%

mentioning

confidence: 99%

Efficient multi-angle polarimetric inversion of aerosols and ocean color powered by a deep neural network forward model

et al. 2021

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show abstract

“…OCI will provide continuous spectral measurements from the ultraviolet (340 nm) to near-infrared (890 nm) with Full Width Half Maximum of 5 nm resolution and sampling every 2.5 nm, plus a set of seven discrete shortwave infrared (SWIR) bands centered at 940, 1038, 1250, 1378, 1615, 2130, and 2260 nm. SPEXone performs multiangle measurements at 5 along track viewing angles of 0 • , ±20 • and ±58 • , with a surface swath of 100km, and a continuous spectral range spanning 385-770 nm at resolutions of 2-3 nm for intensity and 10-40 nm for polarization (Rietjens et al, 2019). HARP2 is a wide field-of-view imager that measures the polarized radiances at 440, 550, 670, and 870 nm, 2 https://doi.org/10.5194/amt-2020-507 Preprint.…”

Section: Introductionmentioning

confidence: 99%

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Gao

2021

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“…HARP2 is a wide field-of-view imager that measures polarized radiances at 440, 550, 670, and 865 nm, where the 670 nm band will be at 60 viewing angles and the other bands at 10 viewing angles. SPEXone is a narrow swath imager that performs multi-angle measurements at 5 viewing angles of 0 • , ±20 • and ±58 • on ground, in a continuous spectral range spanning 385-770 nm with a resolution of 2-3 nm for intensity, and 10-40nm for polarization (Rietjens et al, 2019).…”

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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Expected performance and error analysis for SPEXone, a multi-angle channeled spectropolarimeter for the NASA PACE mission

Cited by 17 publications

References 13 publications

Efficient multi-angle polarimetric inversion of aerosols and ocean color powered by a deep neural network forward model

Efficient multi-angle polarimetric inversion of aerosols and ocean color powered by a deep neural network forward model

Reply on RC3

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

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