5.2 Retrieving PM2.5 Concentrations over the Contiguous United States through the Use of CALIOP and HSRL Observations

Wednesday, 15 January 2020: 1:45 PM
209 (Boston Convention and Exhibition Center)
Travis D. Toth, NASA Langley Research Center, Hampton, VA; and J. Zhang, M. A. Vaughan, J. S. Reid, and J. R. Campbell

Particulate matter with diameters less than 2.5 µm (PM2.5) adversely affects air quality and human health. In the past, satellite-based PM2.5 studies mostly concentrated on deriving surface PM2.5 concentrations using correlative relationships between satellite retrieved aerosol optical depth (AOD) and PM2.5 concentrations. Such studies are fundamentally flawed, as AOD is a column-integrated quantity and PM2.5 is a surface-based parameter. Using a bulk-mass-modeling-based method, we demonstrate the feasibility of deriving surface PM2.5 concentrations using near-surface aerosol extinction retrievals from the NASA Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument, bulk mass extinction efficiencies, and model-based hygroscopicity. The newly developed method is applied to CALIOP aerosol extinction retrievals using nearly the entire CALIOP data record (2007-2018), and the derived PM2.5 values were further evaluated using ground-based PM2.5 measurements from the U.S. Environmental Protection Agency (EPA). The potential of applying similar methods to measurements from the NASA Langley airborne High Spectral Resolution Lidar (HSRL) is also investigated. Lastly, we evaluate uncertainties in our method to examine the subsequent uncertainties in derived PM2.5 as one way to assess the usefulness of future space-based lidars for PM2.5 monitoring and forecasting.
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