## Atmospheric Greenhouse Gas Levels

Given an air pollutant concentration at sea-level atmospheric pressure, the concentration at higher altitudes can be obtained from this equation:

{\displaystyle C_{\mathrm {h} }=C\,\cdot {\bigg (}{\frac {288-6.5h}{288}}{\bigg )}^{5.2558}}C_\mathrm h = C\,\cdot\bigg(\frac{288 – 6.5 h}{288}\bigg)^{5.2558}

where:

h = altitude, in km

P = atmospheric pressure at sea level

Ph = atmospheric pressure at altitude h

C

= Air pollutant concentration, in mass per unit volume at sea level atmospheric pressure and specified temperature T

Ch = Concentration, in mass per unit volume at altitude h and specified temperature T

As an example, given an air pollutant concentration of 260 mg/m3 at sea level, calculate the equivalent pollutant concentration at an altitude of 2800 meters:

Ch = 260 × [ { 288 – (6.5)(2.8) } / 288] 5.2558 = 260 × 0.71 = 185 mg/m3

Note:

The above equation for the decrease of air pollution concentrations with increasing altitude is applicable only for about the first 10 km of altitude in the troposphere (the lowest atmospheric layer) and is estimated to have a maximum error of about 3 percent. However, 10 km of altitude is sufficient for most purposes involving air pollutant concentrations.