On the use of simulated photon paths to co‐register top‐of‐atmosphere radiances in <i>EarthCARE</i> radiative closure experiments

Tornow, Florian; Barker, Howard; Domenech, C.

doi:10.1002/qj.2606

Cited by 4 publications

(2 citation statements)

References 31 publications

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“…Buffer-zone also accommodate the fact that the BBR's oblique radiances associated with consist partly of photons that were scattered by the atmosphere and surface outside of . Barker et al (2015) described an adjustment to 3D 120 RT Monte Carlo models that approximates fractional contributions to a BBR radiance from photons whose last scattering event, by any particular scattering species, took place in . Their algorithm, however, is too time-consuming for EarthCARE's official data processing system.…”

Section: Assessment Domains and Their Buffer-zonesmentioning

confidence: 99%

Across-track Extension of Retrieved Cloud and Aerosol Properties for the EarthCARE Mission: The ACM-3D Product

Barker

Cole

et al. 2022

Preprint

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Abstract. The narrow cross-section of cloud and aerosol properties retrieved by L2-algorithms that operate on data from EarthCARE’s nadir-pointing sensors gets “broadened” across-track by an algorithm that is described and demonstrated here. This Scene Construction Algorithm (SCA) consists of four sub-algorithms. At its core is a radiance-matching procedure that works with measurements made by EarthCARE’s Multi-Spectral Imager (MSI). In essence, an off-nadir pixel gets filled with retrieved profiles that are associated with a (nearby) nadir pixel whose MSI radiances best match those of the off-nadir pixel. The SCA constructs a 3D array of cloud and aerosol (and surface) properties for entire frames that measure ~6,000 km along-track by 150 km across-track (i.e., the MSI’s full swath). Constructed domains out to ~15 km on both sides of nadir are used explicitly downstream as input for 3D radiative transfer models that predict top-of-atmosphere (TOA) broadband solar and thermal fluxes and radiances. These quantities are compared to com-mensurate measurements made by EarthCARE’s BroadBand Radiometer (BBR), thus facilitating a continuous closure assessment of the retrievals. Three 6,000 km x 200 km frames of synthetic EarthCARE observations were used to demonstrate the SCA. The main conclusion is that errors in modelled TOA fluxes that stem from use of 3D domains produced by the SCA are expected to be less than ±5 W m-2 and rarely larger than ±10 W m-2. As such, the SCA, as purveyor of in-formation needed to run 3D radiative transfer models, should help more than hinder the radiative closure assessment of EarthCARE’s L2 retrievals.

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Section: Assessment Domains and Their Buffer-zonesmentioning

confidence: 99%

Across-track Extension of Retrieved Cloud and Aerosol Properties for the EarthCARE Mission: The ACM-3D Product

Barker

Cole

et al. 2022

Preprint

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“…The 3D information of the atmosphere based on measurements of these instruments (Mason et al, 2023) will be used as input for 1D and 3D-radiative transfer calculations (Cole et al, 2022). The calculated top-of-atmosphere (TOA) solar and thermal fluxes leaving Earth to space are finally compared to the short and longwave fluxes, estimated from radiance measurements from the broad-band radiometer (BBR) to achieve radiative closure (Tornow et al, 2015;Barker et al, 2024).…”

Section: Introductionmentioning

confidence: 99%

Retrieval of top-of-atmosphere fluxes from combined EarthCARE LiDAR, imager and broadband radiometer observations: the BMA-FLX product

Velázquez Blázquez,

Domenech,

Baudrez

et al. 2024

Preprint

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Abstract. The Earth Cloud, Aerosol and Radiation Explorer (EarthCARE) satellite mission is expected to provide new insights into aerosols, clouds, and radiation. The satellite’s payload include four instruments design to synergistically retrieve vertical profiles of clouds and aerosols, along with the atmospheric radiation data. This will enable the determination of atmospheric heating rates and top-of-atmosphere radiances and fluxes. This paper focuses on the BMA-FLX processor, an algorithm specifically created, developed, and validated to retrieve thermal and solar top-of-atmosphere radiative fluxes from longwave and shortwave radiances, measured along-track by the EarthCARE Broadband Radiometer (BBR) instrument. These measurements are co-registered either at the surface or at the radiatively most significant vertical layer of the atmosphere in cloudy condition (reference level). The Multi-Spectral Imager (MSI) and Atmospheric LiDAR (ATLID) on-board EarthCARE support cloud identification, while meteorological data from the European Centre for Medium-Range Weather Forecasts provide the surface and atmospheric necessary information. In the BMA-FLX processor, flux is estimated independently for each BBR view using different approaches for the longwave and shortwave radiances. A combined flux, derived from co-registered radiances at the reference level, is provided as the best estimate for a given scene. The radiance-to-flux conversion algorithms have been successfully validated through end-to-end verification using L1 and L2 synthetic data for three EarthCARE orbits. The BMA-FLX’s objective is to achieve radiative closure for EarthCARE with solar and thermal fluxes within 10 Wm−2.

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Across-track extension of retrieved cloud and aerosol properties for the EarthCARE mission: the ACMB-3D product

Qu,

Barker,

Cole

et al. 2023

Atmos. Meas. Tech.

View full text Add to dashboard Cite

Abstract. The narrow cross section of cloud and aerosol properties retrieved by L2 algorithms that operate on data from EarthCARE's nadir-pointing sensors is broadened across-track by an algorithm that is described and demonstrated here. This scene construction algorithm (SCA) consists of four components. At its core is a radiance-matching procedure that works with measurements made by EarthCARE's Multi-Spectral Imager (MSI). In essence, an off-nadir pixel gets filled with retrieved profiles that are associated with a (nearby) nadir pixel whose MSI radiances best match those of the off-nadir pixel. The SCA constructs a 3D array of cloud and aerosol (and surface) properties for entire frames that measure ∼6000 km along-track by 150 km across-track (i.e., the MSI's full swath). Constructed domains out to ∼15 km across-track on both sides of nadir are used explicitly downstream as input for 3D radiative transfer models that predict top-of-atmosphere (TOA) broadband solar and thermal fluxes and radiances. These quantities are compared to commensurate measurements made by EarthCARE's Broadband Radiometer (BBR), thus facilitating a continuous closure assessment of the retrievals. Three 6000 km ×200 km frames of synthetic EarthCARE observations were used to demonstrate the SCA. The main conclusion is that errors in modelled TOA fluxes that stem from use of 3D domains produced by the SCA are expected to be less than ±5 W m−2 and rarely larger than ±10 W m−2. As such, the SCA, as purveyor of information needed to run 3D radiative transfer models, should help more than hinder the radiative closure assessment of EarthCARE's L2 retrievals.

show abstract

On the use of simulated photon paths to co‐register top‐of‐atmosphere radiances in EarthCARE radiative closure experiments

Cited by 4 publications

References 31 publications

Across-track Extension of Retrieved Cloud and Aerosol Properties for the EarthCARE Mission: The ACM-3D Product

Across-track Extension of Retrieved Cloud and Aerosol Properties for the EarthCARE Mission: The ACM-3D Product

Retrieval of top-of-atmosphere fluxes from combined EarthCARE LiDAR, imager and broadband radiometer observations: the BMA-FLX product

Across-track extension of retrieved cloud and aerosol properties for the EarthCARE mission: the ACMB-3D product

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