Please resize the browser if needed to fit the text and graphic
Forecast Graphics Descriptions
Supported by the Northwest Modeling Consortium

Ventilation Index

DEFINITION:

Product of the mixing height (m) and the transport wind speed (m/s) used as a tool for air quality forecasters to determine the potential of the atmosphere to disperse contaminants such as smoke or smog. The University of Washington - Dept. of Atmospheric Sciences uses the product of the planetary boundary layer (PBL) height (m) and 20m wind speed (m/s) to calculate the ventilation index.

Below is a table to describe the values of the Ventilation Index. There are many different interpretations of this value as the description (i.e. GOOD, POOR) is very subjective.

Ventilation Index
(square meters per second)
Classification
0-235 Very poor
235-2350 Poor
2350-4700 Marginal
4700+ Good