Comparisons of bispectral and polarimetric retrievals of marine boundary layer cloud microphysics: case studies using a LES–satellite retrieval simulator
| dc.contributor.author | Miller, Daniel J. | |
| dc.contributor.author | Zhang, Zhibo | |
| dc.contributor.author | Platnick, Steven | |
| dc.contributor.author | Ackerman, Andrew S. | |
| dc.contributor.author | Werner, Frank | |
| dc.contributor.author | Cornet, Celine | |
| dc.contributor.author | Knobelspiesse, Kirk | |
| dc.date.accessioned | 2018-09-12T19:16:31Z | |
| dc.date.available | 2018-09-12T19:16:31Z | |
| dc.date.issued | 2018-06-26 | |
| dc.description.abstract | Many passive remote-sensing techniques have been developed to retrieve cloud microphysical properties from satellite-based sensors, with the most common approaches being the bispectral and polarimetric techniques. These two vastly different retrieval techniques have been implemented for a variety of polar-orbiting and geostationary satellite platforms, providing global climatological data sets. Prior instrument comparison studies have shown that there are systematic differences between the droplet size retrieval products (effective radius) of bispectral (e.g., MODIS, Moderate Resolution Imaging Spectroradiometer) and polarimetric (e.g., POLDER, Polarization and Directionality of Earth's Reflectances) instruments. However, intercomparisons of airborne bispectral and polarimetric instruments have yielded results that do not appear to be systematically biased relative to one another. Diagnosing this discrepancy is complicated, because it is often difficult for instrument intercomparison studies to isolate differences between retrieval technique sensitivities and specific instrumental differences such as calibration and atmospheric correction. In addition to these technical differences the polarimetric retrieval is also sensitive to the dispersion of the droplet size distribution (effective variance), which could influence the interpretation of the droplet size retrieval. To avoid these instrument-dependent complications, this study makes use of a cloud remote-sensing retrieval simulator. Created by coupling a large-eddy simulation (LES) cloud model with a 1-D radiative transfer model, the simulator serves as a test bed for understanding differences between bispectral and polarimetric retrievals. With the help of this simulator we can not only compare the two techniques to one another (retrieval intercomparison) but also validate retrievals directly against the LES cloud properties. Using the satellite retrieval simulator, we are able to verify that at high spatial resolution (50m) the bispectral and polarimetric retrievals are highly correlated with one another within expected observational uncertainties. The relatively small systematic biases at high spatial resolution can be attributed to different sensitivity limitations of the two retrievals. In contrast, a systematic difference between the two retrievals emerges at coarser resolution. This bias largely stems from differences related to sensitivity of the two retrievals to unresolved inhomogeneities in effective variance and optical thickness. The influence of coarse angular resolution is found to increase uncertainty in the polarimetric retrieval but generally maintains a constant mean value. | en_US |
| dc.description.sponsorship | The hardware used in the computational studies is part of the UMBC High Performance Computing Facility (HPCF). The facility is supported by the US National Science Foundation through the MRI program (grant nos. CNS0821258 and CNS-1228778) and the SCREMS program (grant no. DMS-0821311), with additional substantial support from the University of Maryland, Baltimore County (UMBC). See https://hpcf.umbc.edu/ (last access: 12 June 2018) for more information on HPCF and the projects using its resources. | en_US |
| dc.description.uri | https://www.atmos-meas-tech.net/11/3689/2018/ | en_US |
| dc.format.extent | 27 pages | en_US |
| dc.genre | journal article | en_US |
| dc.identifier | doi:10.13016/M2F18SJ6N | |
| dc.identifier.citation | Daniel J. Miller, Zhibo Zhang, Steven Platnick, Andrew S. Ackerman, Frank Werner, Celine Cornet, Kirk Knobelspiesse, Comparisons of bispectral and polarimetric retrievals of marine boundary layer cloud microphysics: case studies using a LES–satellite retrieval simulator, Atmospheric Measurement Techniques Volume 11, issue 6, 2018, 3689-3715, https://doi.org/10.5194/amt-11-3689-2018 | en_US |
| dc.identifier.uri | https://doi.org/10.5194/amt-11-3689-2018 | |
| dc.identifier.uri | http://hdl.handle.net/11603/11286 | |
| dc.language.iso | en_US | en_US |
| dc.publisher | Copernicus Publications | en_US |
| dc.relation.isAvailableAt | The University of Maryland, Baltimore County (UMBC) | |
| dc.relation.ispartof | UMBC Joint Center for Earth Systems Technology | |
| dc.relation.ispartof | UMBC Faculty Collection | |
| dc.relation.ispartof | UMBC Physics Department | |
| dc.rights | This item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author. | |
| dc.rights | Attribution 4.0 International (CC BY 4.0) | * |
| dc.rights.uri | https://creativecommons.org/licenses/by/4.0/ | * |
| dc.subject | Moderate Resolution Imaging Spectroradiometer ( MODIS) | en_US |
| dc.subject | Polarization and Directionality of Earth's Reflectances ( POLDER) | en_US |
| dc.subject | large-eddy simulation (LES) | en_US |
| dc.subject | UMBC High Performance Computing Facility (HPCF) | en_US |
| dc.title | Comparisons of bispectral and polarimetric retrievals of marine boundary layer cloud microphysics: case studies using a LES–satellite retrieval simulator | en_US |
| dc.type | Text | en_US |