HR: 1340h
AN: A23A-0882    [Abstracts]
TI: CALIPSO Aerosol Backscatter and Extinction Characterization Using the MODIS and OMI Products
AU: Vaughan, M
EM: mark.a.vaughan@nasa.gov
AF: Science Systems and Applications INC., NASA Langley Research Center, Hampton, VA 23681, United States
AU: * Kittaka, C
EM: Chieko.Kittaka-1@nasa.gov
AF: Science Systems and Applications INC., NASA Langley Research Center, Hampton, VA 23681, United States
AU: Winker, D
EM: david.m.winker@nasa.gov
AF: NASA Langley Research Center, NASA Langley Research Center, Hampton, VA 23681, United States
AU: Omar, A
EM: ali.h.omar@nasa.gov
AF: NASA Langley Research Center, NASA Langley Research Center, Hampton, VA 23681, United States
AU: Liu, Z
EM: Zhaoyan.Liu-1@nasa.gov
AF: National Institute of Aerospace, NASA Langley Research Center, Hampton, VA 23681, United States
AU: Young, S
EM: Stuart.Young@csiro.au
AF: CSIRO Atmospheric Rearch, PMB 1, Aspendale, VIC 3195, Australia
AU: Trepte, C
EM: Charles.R.Trepte@nasa.gov
AF: NASA Langley Research Center, NASA Langley Research Center, Hampton, VA 23681, United States
AB: The CALIPSO lidar observations accumulated since June 2006 have revealed the vertical structure of aerosols in the Earth's atmosphere on an unprecedented global scale. Combining the vertical curtain of CALIPSO data with the wide swath of passive sensor measurements provided by MODIS and/or OMI will allow us not only to depict the three-dimensional distribution of aerosols on a global scale, but also to develop and improve joint retrieval algorithms that take full advantage of the strengths of each instrument. As a first step in this data fusion process, we conduct a statistical analysis comparing the CALIPSO integrated attenuated backscatter (IAB) and aerosol optical depths (AOD) measured at 532 nm to the aerosol data products generated by the MODIS sensor aboard the AQUA satellite and by the OMI instrument flying on the AURA satellite. This analysis includes seasonal and geographical variations of the CALIPSO aerosol IAB, and comparisons with collocated MODIS AOD retrievals. Comparisons are also made to the OMI aerosol index (AI) product, which complements the MODIS AOD over bright surfaces where the MODIS retrieval tends to show diminished accuracies. The combination of CALIPSO IAB and MODIS AOD is then used to infer the aerosol extinction-to-backscatter ratio (lidar ratio), which is a function of chemical composition and particle size distribution, and can be an indicator for aerosol speciation. The CALIPSO analysis framework defines six generic aerosol species or types: clean marine, dust, polluted dust, clean continental, polluted continental, and biomass burning. Separate geographic regions are identified where a single type dominates the local aerosol burden. Within each of these regions, the CALIPSO AOD, which is reported at a spatial resolution of 5-km x ~90-m (90-m is the approximate diameter of the laser footprint), is averaged to 10-km average horizontally. These data are then compared with the coincident MODIS AOD estimates, which are retrieved at a spatial resolution of 10-km x 10-km. Discrepancies between the two measurements may involve difficulties in AOD retrieval over different surface types, or the multi-layer structures of aerosols and clouds. The high spatial resolution of a CALIPSO vertical profile and the nature of an active remote sensing instrument allows unambiguous identification of such cases, and should help improve data quality for the passive sensor retrievals.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0360 Radiation: transmission and scattering
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting