Definition and conversion of volume mixing ratio
The volume mixing ratio, or simply mixing ratio, of a gas is defined as the ratio of the number density of the gas to the total number density of the atmosphere. In other words, ozone volume mixing ratio is the density of ozone divided by the density of all constituents in a unit volume (i.e. number of molecules per unit volume).
Therefore, an ozone mixing ratio of 10-6 means that the number density of ozone is 10-6 times the total number density of air in a unit volume. Following the standard convention for the Earth's troposphere and stratosphere, this mixing ratio equals 1 ppmv (parts per million by volume).
Conversion of volume mixing ratio
Below conversions of ozone volume mixing ratio (vmr) into common units are
pO3 = vmrO3 * pressure
ρO3 = vmrO3 * 577.3 * pressure / temperature
mO3 = vmrO3 * 1.66
NO3 = vmrO3 * pressure / (1.38 10-19 * temperature)
Conversion into volume mixing ratio
Below conversions of common units into ozone volume mixing ratio (vmr) are
vmrO3 = pO3 / pressure
vmrO3 = ρO3 * 1.7322 * 10-3 * temperature / pressure
vmrO3 = mO3 * 0.602
vmrO3 = NO3 * 1.38 10-19 * temperature / pressure
Thilo Erbertseder, Frank Baier, last modified: October 2005