Abstract
The slant-path (or zenith-angle scanning) lidar technique is used to measure boundary-layer optical depths for ten different times during a single day. For the range of optical depths encountered (0.03–0.14 at 0.69 μm wavelength), 1σ measurement uncertainties are about 0.03. The major source of uncertainty is daytime skylight background, effects of which are mitigated in this experiment by the low boundary-layer top height (<1.4 km above the lidar). Resulting particle column backscatter-to-extinction ratios vary between 0.010 and 0.053 sr−1. By assuming that these ratios are independent of height, vertical extinction profiles and the optical depth of a layer below a tower-mounted radiometer pair are derived. This radiometer pair is used to measure the change in surface plus layer albedo caused by the aerosol layer. The consistency of albedo and optical thickness measurements is tested by comparing measured albedo changes to those calculated from the optical thickness measurements. When reasonable values are assumed for particle refractive index and relative size distribution (not measured in this experiment), results agree to within the uncertainty arising from the 0.03 optical thickness measurement uncertainty.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.