Visualization of measurement profiles - BLVIEW - CL61

BL-View for CL61 User Guide

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User guide

The laser pulse emitted by the ceilometer is scattered by each particle it encounters on its path through the atmosphere. A portion of this light is scattered back towards the instrument and is registered. The rest of the light is either absorbed or scattered in directions not seen by the ceilometer. The portion of backscattered light registered by the ceilometer is called attenuated backscatter.

Each particle also interacts with the laser pulse by either maintaining or altering the polarization of the emitted light. The ceilometer registers changes in polarization and reports them as profiles called the linear depolarization ratio. The information in these profiles can be used to differentiate between liquid and solid particles.

CL61 is able to report the following vertical profiles:

  • Parallel-polarized attenuated backscatter profile (PPOL)
  • Cross-polarized attenuated backscatter profile (XPOL)
  • Total attenuated backscatter profile (ABS = PPOL + XPOL)
  • Depolarization ratio profile (LDR = XPOL / PPOL)

Profiles are reported at 4.8 m (15.75 ft) height intervals.

LDR varies between 0 and 1.

In BL-View, you can adjust the depolarization limit (LDR) in Presets.

The following figure shows the linear depolarization ratio profile with clouds.