IPRT polarized radiative transfer model intercomparison project – Three-dimensional test cases (phase B)

Emde, Claudia; Barlakas, Vasileios; Cornet, Céline; Evans, K. Franklin; Wang, Zhen; Labonotte, Laurent C.; Macke, Andreas; Mayer, Bernhard; Wendisch, Manfred

doi:10.1016/j.jqsrt.2018.01.024

Cited by 38 publications

(22 citation statements)

References 46 publications

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“…The AERONET station CUT-TEPAK is installed about 300 m to the east. The Leipzig Aerosol and Cloud Re-mote Observations System (LACROS; Bühl et al, 2013), including a Polly XT lidar system (Engelmann et al, 2016), was located 400 m to the northeast. Between 6 and 28 April, SSARA continuously performed direct Sun observations.…”

Section: Case Studiesmentioning

confidence: 99%

The polarized Sun and sky radiometer SSARA: design, calibration, and application for ground-based aerosol remote sensing

et al. 2020

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Abstract. Recently, polarimetry has been used to enhance classical photometry to infer aerosol optical properties, as polarized radiation contains additional information about the particles. Therefore, we have equipped the Sun–sky automatic radiometer (SSARA) with polarizer filters to measure linearly polarized light at 501.5 nm. We describe an improved radiometric and polarimetric calibration method, which allows us to simultaneously determine the linear polarizers' diattenuation and relative orientation with high accuracy (0.002 and 0.1∘, respectively). Furthermore, we employed a new calibration method for the alt-azimuthal mount capable of correcting the instrument's pointing to within 32 arcmin. So far, this is limited by the accuracy of the Sun tracker. Both these methods are applicable to other Sun and sky radiometers, such as the Cimel CE318-DP instruments used in the AErosol RObotic NETwork (AERONET). During the A-LIFE (Absorbing aerosol layers in a changing climate: aging, LIFEtime and dynamics) field campaign in April 2017, SSARA collected 22 d of data. Here, we present two case studies. The first demonstrates the performance of an aerosol retrieval from SSARA observations under partially cloudy conditions. In the other case, a high aerosol load due to a Saharan dust layer was present during otherwise clear-sky conditions.

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Section: Case Studiesmentioning

confidence: 99%

The polarized Sun and sky radiometer SSARA: design, calibration, and application for ground-based aerosol remote sensing

et al. 2020

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“…To test these tools in the context of multiple scattering, we implemented several benchmark experiments and compared our calculations against published results, for example, Table 1 of Galtier et al (2013), and against the solution of the well-validated 3DMCPOL (Cornet et al, 2010) on the IPRT cubic cloud case (Emde et al, 2018; see supporting information). Agreement was found within the MC statistical uncertainty, thus validating our implementation.…”

Section: C12 Cloudsmentioning

confidence: 99%

A Path‐Tracing Monte Carlo Library for 3‐D Radiative Transfer in Highly Resolved Cloudy Atmospheres

Villefranque

Fournier

Couvreux

et al. 2019

J Adv Model Earth Syst

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Interactions between clouds and radiation are at the root of many difficulties in numerically predicting future weather and climate and in retrieving the state of the atmosphere from remote sensing observations. The broad range of issues related to these interactions, and to three‐dimensional interactions in particular, has motivated the development of accurate radiative tools able to compute all types of radiative metrics, from monochromatic, local, and directional observables to integrated energetic quantities. Building on this community effort, we present here an open‐source library for general use in Monte Carlo algorithms. This library is devoted to the acceleration of ray tracing in complex data, typically high‐resolution large‐domain grounds and clouds. The main algorithmic advances embedded in the library are related to the construction and traversal of hierarchical grids accelerating the tracing of paths through heterogeneous fields in null‐collision (maximum cross‐section) algorithms. We show that with these hierarchical grids, the computing time is only weakly sensitive to the refinement of the volumetric data. The library is tested with a rendering algorithm that produces synthetic images of cloud radiances. Other examples of implementation are provided to demonstrate potential uses of the library in the context of 3‐D radiation studies and parameterization development, evaluation, and tuning.

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“…In general, all models in Table A1 were run in high accuracy mode (e.g., 128 streams for spheroidal aerosol cases), and the results provide a good dataset for analyzing the accuracy of the low (6) stream VLIDORT approximation. Details of each model can be found in Emde et al [68], and the model outputs for all scenarios were downloaded from the following website: http://www.meteo.physik. uni-muenchen.de/~iprt/doku.php?id=intercomparisons:intercomparisons.…”

Section: Appendix a Vlidort Benchmarking And Toa Radiance Uncertaintmentioning

confidence: 99%

A Geostationary Instrument Simulator for Aerosol Observing System Simulation Experiments

et al. 2018

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In the near future, there will be several new instruments measuring atmospheric composition from geostationary orbit over North America, East Asia, and Europe. This constellation of satellites will provide high resolution, time resolved measurements of trace gases and aerosols for monitoring air quality and tracking pollution sources. This paper describes a detailed, fast, and accurate (less than 1.0% uncertainty) method for calculating synthetic top of the atmosphere (TOA) radiances from a global simulation with a mesoscale free running model, the GEOS-5 Nature Run, for remote sensing instruments in geostationary orbit that measure in the ultraviolet-visible spectral range (UV-Vis). Generating these synthetic observations is the first step of an Observing System Simulation Experiment (OSSE), a framework for evaluating the impact of a new observation or algorithm. This paper provides details of the model sampling, aerosol and cloud optical properties, surface reflectance modeling, Rayleigh scattering calculations, and a discussion of the uncertainties of the simulated TOA radiance. An application for the simulated TOA radiance observations is demonstrated in the manuscript. Simulated TEMPO (Tropospheric Emissions: Monitoring of Pollution) and GOES-R (Geostationary Operational Environmental Satellites) observations were used to show how observations from the two instruments could be combined to facilitate aerosol type discrimination. The results demonstrate the viability of a detailed instrument simulator for radiance measurements in the UV-Vis that is capable of accurately simulating high resolution, time-resolved measurements with reasonable computational efficiency.Atmosphere 2019, 10, 2 2 of 36 spectral range (UV-Vis). The large-scale, time-resolved measurements of these pollutants provided by the geostationary constellation are important for managing air quality, and understanding how human activity impacts local, regional, and global distributions of pollution, as well as global climate.Aerosols are one of the most important forcing agents in the climate system. They can be transported around the globe [4], and interact with weather systems [5], scatter and absorb radiation [6][7][8], and modify cloud properties [9,10]. Routine measurements of various aerosol parameters, such as aerosol optical depth (AOD), absorbing aerosol optical depth (AAOD), aerosol index (AI), and single scattering albedo (SSA), are currently available from several sensors in low earth orbit (LEO). These sensors include the twin MODIS (Moderate Resolution Imaging Spectroradiometer) instruments (on-board Terra and Aqua), MISR (Multi-angle Imaging SpectroRadiometer), OMI (Ozone Monitoring Instrument), and POLDER (Polarization and Directionality of the Earth Reflectances) (see Table 1 in [11]). In addition, CALIOP, a spaceborne LiDAR, measures the vertical distribution of aerosol backscattering.Instruments in LEO provide one or two measurements per day, but as aerosol parameters cannot be retrieved under cloudy conditions there can be a l...

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IPRT polarized radiative transfer model intercomparison project – Three-dimensional test cases (phase B)

Cited by 38 publications

References 46 publications

The polarized Sun and sky radiometer SSARA: design, calibration, and application for ground-based aerosol remote sensing

The polarized Sun and sky radiometer SSARA: design, calibration, and application for ground-based aerosol remote sensing

A Path‐Tracing Monte Carlo Library for 3‐D Radiative Transfer in Highly Resolved Cloudy Atmospheres

A Geostationary Instrument Simulator for Aerosol Observing System Simulation Experiments

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