Simultaneous observations of boundary-layer aerosol layers with CL31 ceilometer and 1064/532 nm lidar

Aerosol backscatter measurements from a Vaisala CL31 ceilometer are compared directly with a co-located 532/1064 nm lidar in order to validate the CL31 for remote sensing of vertical aerosol structure. The cases examined include a significant aerosol event (biomass burning), which by virtue of its vertical extent, provides a robust measure of the vertical range of the ceilometer for aerosol applications. A second case is presented when the instruments were separated in order to illustrate the utility of a network of such instruments for elucidating spatial patterns in aerosol distribution and the advection of elevated pollutant layers. When co-located, the instruments show remarkable agreement and indicate that the CL31 can detect aerosol layers up to 3000 m AGL in ideal conditions (at night and with high aerosol concentrations as found in biomass burning or dust plumes). When separated, multiple instruments provide an opportunity to examine advection of pollutant layers as well as their evolution. This suggests that installation of a ceilometer network would provide a cost-effective means of examining three-dimensional aspects of regional air quality as well as distinguishing between regional and local sources of pollution