92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Thursday, 26 January 2012: 9:00 AM
Smoke Plumes Optical Properties and Transport Observed by a Multi-Wavelength Lidar, Sunphotometer and Satellite
Room 339 (New Orleans Convention Center )
Lina Cordero, City College of New York, New York, NY; and Y. Wu, B. Gross, F. Moshary, and S. Ahmed
Manuscript (794.5 kB)

Forest-fire and biomass burning often inject large amounts of smoke aerosols into atmosphere in North America, and these plumes can be elevated into free troposphere and transported over long-distances. The smoke plumes can also mix into the planetary-boundary-layer (PBL) during the transport Observations also indicate that the aerosol plumes potentially modify cloud physical, chemical and optical properties Therefore, smoke plumes affect the climate radiation, air quality and visibility in the regional and continental scale. The occurrence, transport and column optical properties of smoke plumes have been extensively investigated by satellite-borne and ground-based radiometers. Vertical structure and optical characteristic of aerosol plumes were also observed by lidar.. Dual-wavelength Raman lidar has observed the aged Siberian smoke, dust plumes and derived their optical-microphysical properties; smoke particle size and a high wavelength dependence of lidar-ratio (extinction-to-backscatter ratio) were found to be strongly associated with the fire origin, strength and transport process. However, in the daytime, the capability of Raman lidar measuring aerosol is largely limited in the lower troposphere because of its inherent weak signal-to-noise ratio caused by strong daylight noise. Under this situation, a combination of elastic lidar and sunphotometer measurements can provide the constraint of aerosol extinction and backscatter profile and thereby complement aloft smoke plume retrievals in the daytime measurement. In this study, the combined observations of smoke plumes from a ground-based multi-wavelength lidar, sun/sky radiometer and MODIS and CALIOP satellites are presented. We focus in particular on two representative events to retrieve aerosol plumes optical characteristics and track their intra-continent transport. Multi-wavelength extinction profiles of aerosol plume are first derived by constraining lidar profiles with sunphotometer-measured column AOD, and then Angstrom exponents are obtained to discriminate smoke plumes from cloud and dust particles. Long-distance transport and origins of smoke plume are illustrated by satellite MODIS/Aqua, CALIOP imageries and NOAA/HYSPLIT air backward trajectory analysis. Most importantly, we show that aloft smoke plumes may mix downward into the PBL and potentially result in the increase of surface PM2.5 concentrations and that these mixings are a major factor in enhanced pollution enhancement during the summer when the PBL is high allowing for improved mixing. In analyzing these cases, we show that lidar measurements are critical to properly apportion the AOD between the PBL and aloft layers allowing us to better quantify the surface PM2.5 concentration variation.

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