613 Webex Seminar: Reed Espinosa

NASA/Climate & Radiation Laboratory


William (Reed) Espinosa
Climate & Radiation Laboratory WEBEX Seminar

Please note Webex information following abstract

Exploring the capabilities of synergistic passive and active remote sensing with a new aerosol retrieval testbed

Passive aerosol sensors composing the present generation of space-based instrumentation generally permit measurements spanning the majority of the shortwave spectrum, or observations at multiple viewing angles, but rarely both. Moreover, very few of these instruments possess sensitivity to polarization, and those that do lack the accuracy required to fully utilize this quantity. This limited information content generally confines current operational aerosol retrievals to only a few parameters, like Aerosol Optical Depth (AOD) and fine-mode fraction. In principle, active observations can supplement the information provided by passive sensors but this approach has been limited by the small number of these sensors deployed to orbit and by elastic LIDAR’s inability to constrain the extinction-to-backscatter ratio—a parameter that can now be obtained directly with new, presently sub-orbital, technologies like High Spectral Resolution LIDAR (HSRL). In the next decade, a variety of satellites are expected to launch with sensors that will exceed these current observational limitations, including platforms that concurrently produce measurements of LIDAR profiles and polarimetric radiances. The increased information content in these new datasets is expected to drive significant improvements in aerosol remote sensing capabilities but, if this additional information is to be fully utilized, novel retrieval approaches will have to be developed and tested. In this work, surface parameterizations and synthetic aerosol models derived from AERONET climatologies are used to simulate top-of-atmosphere polarized radiances as well as elastic and inelastic LIDAR profiles. Simulated noise is then added to these quantities to generate synthetic observations that can be fed into the Generalized Retrieval of Aerosol and Surface Properties (GRASP). The resulting inversion products are then compared with the state parameters used to produce the simulated observations (i.e. the modeled “truth”) in order to obtain estimates of retrieval error for different instrument configurations. This new testbed can be used to explore various retrieval approaches as well as optimize future satellite architectures for sensitivity to the desired aerosol properties. In this talk, an analysis of the inversion capabilities of different instrument configurations under various observation scenarios will be presented, with an emphasis on the retrieval improvements afforded by polarization and the inclusion of LIDAR profiles. Investigations are also performed on cases in which the aerosol assumptions modeled by the retrieval diverge from the particle properties used to generate the simulated scenes. In the context of polarimetric measurements, it is found that these modeling errors can significantly impact retrieval performance, especially incorrect assumptions regarding fine and coarse mode particle morphology.


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Meeting number (access code): 909 621 689

Meeting password: HhAjVic$233


Wednesday, April 15, 2020

1:30 pm  |  Eastern Daylight Time (New York, GMT-04:00)  |  1 hr

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