scope:

In addition to wind direction, wind speed, temperature and humidity near ground level, the diffusion of air pollutants also depends on the way that these variables change with altitude (vertical profiles of wind, temperature or humidity, vertical temperature or humidity gradient). The extend of the vertical range of interest depends on each particular task.

The objective of aerological measurements is to obtain the vertical distributions of the measured variables at a fixed location at a particular time.

In general, aerological measurements associated with air pollution are conducted at heights of up to 3000 m above ground. The results are representative in the horizontal dimension over an order of magnitude of a few tens of kilometres; at the lower range of the ascent, they depend considerably on the orographic conditions.

For pollution prevention purposes, information is mostly required about:

• type and frequency of the vertical profiles of wind direction and wind speed

• mechanism and vertical extent of wind systems affected by orographic conditions

• frequency and duration of inversions and their upper and lower limits

• height of the inversion