PHY2505 - Lecture 16 Lidar remote sensing
LIDAR backscatter instrument From Tom Duck, Atmospheric Optics Lab, Dalhousie emitted received time
LIDAR backscatter instrument aerosol properties
LIDAR backscatter
LIDAR backscatter retrieval problem Need to relate backscatter coefficient, b, to volume extinction coefficient, s Generally use normalised power In differential form Assume relationships between b and s in the form b=asb Eg. Water cloud b~ 0.625s. Special case is to asume db/dr=0 – particles uniformly mixed along line of sight (slope method) General problems are 1) the b-s relationship 2) the instability of the solution due to ratio of small numbers (decreasing with range) 2s( r)
LIDAR backscatter profiles (From Stephens, 1994) Lidar backscatter from a typical marine boundary layer
Differential absorption LIDAR Retrieve aerosol properties and gas number densities (NA) from extinction of beam without knowledge of relations between b and s
Differential absorption LIDAR
ESA’s Water vapour lidar expt (WALEX) 925nm DIAL
Space-based LIDAR - LITE
Space-based LIDAR - LITE
Space-based LIDAR - LITE Tropical convective mulitlayer cloud systems Saharan dust
Space-based LIDAR - FUTURE