Variability of Aerosol Properties and Mixing-layer Heights from Airborne High Spectral Resolution Lidar, Ground-based Measurements, and the WRF-Chem Model During CARES and CalNex

Category: Field Campaigns

While WRF-Chem and HSRL PBL heights tend to agree (1), the algorithms can differ in low aerosol loading conditions (2), and other situations (3), perhaps related to temperature gradients. These discrepancies need to be understood and corrected for further comparisons. The image is a flight from CalNex; images showing comparisons from CARES flight will be included in this work.

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) was deployed on board the NASA B200 aircraft for flights over California in May and June of 2010 to aid in characterizing aerosol properties during the CalNex and CARES field campaigns. Measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) were made during nearly 100 flight hours on 31 science flights, many in coordination with other participating research aircraft (DOE G-1, CIRPAS Twin Otter, NOAA WP-3, and NOAA Twin Otter), satellites, and ground sites. The HSRL data are used to characterize the vertical and horizontal distribution of aerosols, provide the vertical context for the airborne in situ measurements acquired from these other aircraft, and to derive the height of the mixing layer (ML). Parameters derived from HSRL data are also used to infer aerosol types and determine the fraction of aerosol optical thickness (AOT) contributed by these types. This work examines the variability of the extensive (dependent on aerosol type and number density) and intensive (dependent on aerosol type only) aerosol properties to aid in describing the broader context of aerosol distributions within and near the Sacramento and Los Angeles regions. WRF-Chem model depictions of aerosol properties and types are compared with measured HSRL aerosol parameters and derived products including the aerosol types and mixing-layer heights. These measurements are examined to evaluate aerosol distributions and transport in the Sacramento region. ML heights derived from HSRL measurements are compared with those derived from radiosonde and ceilometer measurements and from WRF-Chem simulations. Initial comparisons show that the HSRL and radiosonde ML heights from CARES are highly correlated (r^2>0.94) with bias differences less than 40 m. Similar ML height comparisons using data from CalNex also show high correlation but also some large differences; potential explanations for such differences are explored.

http://science.larc.nasa.gov/hsrl/

This poster will be displayed at ASR Science Team Meeting.

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