This part of ISO 28902 mainly specifies the requirements in order to perform visual range lidar measurements

for the determination of direction-dependent meteorological optical range (MOR). The term "visual-range lidar"

is used in this part of ISO 28902 to apply to the lidar systems making visual-range measurements, commonly

referred to as "visibility measurements". Due to physical approximations, quantitative determination is limited

to a meteorological optical range of between 30 m and 2 000 m. For this range, this part of ISO 28902

specifies the performance of visual-range lidar systems utilizing the method of range‑integrated visual-range

measurements based on light extinction. The following parameters can be calculated based on the directiondependent

meteorological optical range:

a) horizontal visual range;

b) vertical visual range;

c) slant visual range.

NOTE The measures for visibility are strongly related to the historical definitions of visibility, which are related to human

observers. The lidar technique extends the definitions to various conditions, such as daylight and night-time conditions.

In addition, this measurement principle enables the user to retrieve information on cloud base height, boundary

layer depth, fog banks and aerosol profiles due to the signal attenuation by water vapour and/or aerosols.

Examples of these applications are given in Annex C.

This part of ISO 28902 can be applied in the following areas:

— meteorological stations;

— airports;

— harbours;

— waterways;

— roads and motorways;

— automotive;

— oil platforms.