Intercomparison of photoacoustic and thermal-optical methods for the measurement of atmospheric elemental carbon

Two independent methods of elemental carbon determination in ambient aerosols are compared. The methods are based on different physical properties of elemental carbon. One method uses thermal desorption and combustion to measure organic and elemental carbon with appropriate correction for the pyrolytic conversion of organic to elemental carbon. The other method, based on the photoacoustic affect, measures the optical absorption of the aerosol in its suspended atmospheric state. Calibration of optical absorption is done with NO₂, and the independently measured absorption coefficient of aerosol elemental carbon. Historically, agreement between different methods of elemental carbon determination has been poor. However, the agreement of these independent methods greatly increases the confidence in the measurements so obtained.