HR: 1340h
AN: A43C-1428    [Abstracts]
TI: Comparison of LIDAR and Cavity Ring-Down Measurements of Aerosol Extinction and Study of Inferred Aerosol Gradients
AU: * Eberhard, W L
EM: Wynn.Eberhard@noaa.gov
AF: NOAA Earth System Research Laboratory, R/CSD3, 325 Broadway, Boulder, CO 80305, United States
AU: Massoli, P
EM: Paola.Massoli@noaa.gov
AF: Cooperative Institute for Research in Environmental Science, University of Colorado / NOAA, R/CSD2, 325 Broadway, Boulder, CO 80305, United States
AU: McCarty, B J
EM: Brandi.McCarty@noaa.gov
AF: Cooperative Institute for Research in Environmental Science, University of Colorado / NOAA, R/CSD3, 325 Broadway, Boulder, CO 80305, United States
AU: Machol, J L
EM: Janet.Machol@noaa.gov
AF: Cooperative Institute for Research in Environmental Science, University of Colorado / NOAA, R/CSD3, 325 Broadway, Boulder, CO 80305, United States
AU: Tucker, S C
EM: Sara.Tucker@noaa.gov
AF: Cooperative Institute for Research in Environmental Science, University of Colorado / NOAA, R/CSD3, 325 Broadway, Boulder, CO 80305, United States
AB: A LIDAR and a Cavity Ring-Down Aerosol Extinction Spectrometer (CRD) instrument simultaneously measured aerosol extinction at 355-nm wavelength from aboard the Research Vessel Ronald H. Brown during the Texas Air Quality Study II campaign. The CRD measured air sampled from the top of the common mast used by several in situ aerosol optical and chemical instruments. The LIDAR's scan sequence included near-horizontal stares (2° elevation angle) with pointing corrected for ship's roll. Aerosol extinction was retrieved using a variant of the slope method. The LIDAR therefore sampled air over a short vertical extent with midpoint higher above the surface than the CRD intake and at a horizontal distance of as much as a few kilometers. The CRD measured aerosol extinction at dry and at high (near-ambient) relative humidity (RH) levels, which were used to scale the measurements to ambient RH for the comparisons. Data from the two instruments for well-mixed conditions (supported by turbulence and atmospheric stability data) are compared to evaluate the degree of agreement between the two methods and reasons for differences. For instances of larger differences, the aerosol gradient below approximately 100 m altitude is inferred and examined in context of low-level meteorological parameters and LIDAR measurements at higher angles.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0394 Instruments and techniques
DE: 3307 Boundary layer processes
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting