Impact of weather conditions - BLVIEW - CL61

BL-View for CL61 User Guide

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The following weather conditions have an impact on the analysis of planetary boundary layer structure.


During precipitation, mixing height or other aerosol layers cannot be reported. This is due to the very high signal from precipitation dominating the backscatter from any remaining aerosol layers, which makes it impossible to distinguish these from the precipitation.

Low-layer clouds

Low-layer clouds appear at height 0–2000 m (0–6560 ft). If there are low-layer clouds, the mixing height is typically situated at the top of the clouds. In these conditions, BL-View does not show the true mixing height due to the measurement principle of Vaisala Ceilometer (LIDAR). In normal conditions, the deviation between the reported local gradient minimum and the top of the cloud is typically less than 200 m (656 ft).

Mid-layer and high-layer clouds

Mid-layer clouds appear at height 2000–5000 m (6560–16 400 ft) and high-layer clouds at height over 5000 m (16 400 ft). Mid-layer clouds and high-layer clouds do not typically create any problems for mixing height measurement. The mixing height is reported normally from the collected data.

Fog or ground-based obscuration

Fog or ground-based obscuration affects the mixing height measurement.

If the fog or ground-based obscuration is too dense, the laser light does not penetrate the layer, which makes it extremely difficult to estimate the mixing height.

In these conditions, Vaisala ceilometers typically report the vertical visibility reading with the highest altitude from which the backscatter signal can be received. If the signal is not strong enough, the mixing height reading is reported automatically.