Intercomparison of photoacoustic and cavity attenuated phase shift instruments: laboratory calibration and field measurements

Abstract. The study of aerosol optical properties is essential to understand its impact on the global climate. In our recent field measurement carried out in Gehu area southwest Changzhou City, a photoacoustic extinctiometer (PAX) and cavity attenuated phase shift albedo monitor (CAPS-ALB) were used for online measurement. Laboratory calibration with gas particle samples correct disagreements measurements. During calibration, we adopted ammonium sulfate (AS) scattering nephelometer parts both instruments, then combined these number-size distribution measurements MIE model calculating value total (extinction) coefficient. employed high concentrations NO2 absorption PAX resonator further intercompared extinction coefficient CAPS-ALB cavity-enhanced spectrometer. correction obtained from laboratory experiments was observed correspondingly showed good results comparison reconstructed IMPROVE model. intercomparison calibrated agreement slopes 1.052, 1.024 1.046 extinction, respectively, which shows reliability verifies correlation between instruments.