Quantities measured by the lidars
10 May 2011



Quantities measured by the lidars


Backscattering coefficient

A quantity related to the scattered power detected by the receiver. It is the basic measure of the calibrated detected signal recorded by a lidar.

Water vapour mass mixing ratio.

The mixing ratio of water vapour per unit mass of dry air.


The radial velocity of scatterers along the line of sight from the lidar to the scatterer.

Linear depolarisation ratio, LDR

The linear depolarisation ratio represents the fraction of energy reflected back in the opposite polarisation to that transmitted by a lidar. It is usually small, but a signal greater than ~5% indicates the presence of non-spherical particles such as ice crystals or asymmetric aerosol particles.

  355 nm Raman 355 nm Leosphere 905 nm Vaisala ceilometer 1550 nm HALO Doppler
Manual steering N Y Y Y
Continuous operation N Y Y Y
Backscattering coefficient Y Y Y Y
Water vapour mass mixing ratio Y N N N
Velocity N N N Y
Linear depolarisation ratio N Y N Y
Contact: Hooper, David (STFC,RAL,RALSP)