HR: 1340h
AN: A43D-1566    [Abstracts]
TI: Ceilometer instrument in NIR for continuous observations of aerosols.
AU: * Gan, C
EM: gross@ccny.cuny.edu
AF: City College of New York, 140th St and Convent Ave, New York, NY 10031, United States
AB: The need for a 24 - 7 vertical aerosol observation is critical to aerosol transport and prediction. To this end, an eye-safe ceilometer usually used only for cloud base measurements was deployed to observe aerosols. We found in direct comparisons with 1064nm lidar measurements that the ceilometer backscatter provides reasonably accurate aerosol backscatter to approximately 1km using spatial bins of 100meters and time averages of 30 minutes baqsed on temporal regression analysis where the 1064nm lidar in the range bin from 900m to 1000m was compared to the ceilometer. Further comparisons at lower altitudes however show that the regression performance is in general good between 500-1000m but an optimum height for best intercomparison is not clear. On the other hand, we note that by 2km, the correlation for "aerosol" signatures has degraded. To assess the utility of the ceilometer instrument, the noise statistics of the ceilometer were explored by examining the range dependence of the mean and std of the signal where we use a threshold of 5e-3 to filter out clouds. The results of the magnitude of the noise signal are presented which determine the minimum optical depth needed to measure a PBL height of a homogeneous layer at a given SNR.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting