Biomass Burning Aerosol Distributions over the Southeastern Atlantic Ocean measured by CALIOP and the NASA LaRC airborne High Spectral Resolution Lidar-2
Abstract
During several months each year, extensive layers of biomass burning smoke are located over the Southeastern Atlantic Ocean where they can interact with the underlying semi-permanent stratocumulus cloud decks. Since this smoke can change cloud structure and coverage and the cloud optical thickness and lifetime, it is important to accurately characterize the proximity of the smoke above the clouds in this region.
We use both CALIOP satellite and NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar-2 measurements to characterize the biomass burning aerosol layers. The HSRL-2 measurements were collected during the NASA EV-S Observations of Aerosols above Clouds and their Interactions (ORACLES) missions in 2016 and 2017. HSRL-2 measured profiles of aerosol backscattering, extinction and aerosol optical depth at 355 and 532 nm and aerosol backscattering and depolarization at 1064 nm and so provided an excellent characterization of the widespread smoke layers above shallow marine clouds. We compute aerosol extinction and backscattering profiles for these layers from CALIOP attenuated backscatter data that are constrained by the CALIOP above cloud aerosol optical depth (ACAOD) using the return signals from the underlying clouds. These profiles provide more accurate ACAOD values and aerosol extinction profiles than the CALIOP V4 operational retrievals. During the July-October period in 2015-2016, these CALIOP profiles show that mean extinction values (532 nm) in the 300 m layer directly above the underlying clouds were above 0.020 km-1 about 55% of the time and above 0.050 km-1 nearly 20% of the time. These values decreased moving westward from the African coast. The HSRL-2 mean aerosol extinction profiles acquired during 2017 show considerably higher aerosol extinction just above the cloud top than profiles from the 2016 ORACLES deployment. In some cases, the HSRL-2 profiles also show vertical variability in aerosol intensive properties indicating changes in aerosol properties such as particle size.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A12C..06F
- Keywords:
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- 0321 Cloud/radiation interaction;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSESDE: 3355 Regional modeling;
- ATMOSPHERIC PROCESSESDE: 3360 Remote sensing;
- ATMOSPHERIC PROCESSES