Measurement of Fundamental Aerosol Physical Properties

Measurements of physical and optical particle properties are essential for evaluating the impact of atmospheric aerosols on atmospheric chemistry, climate, and health. This chapter describes the fundamental equations and conventions pertinent to particle detection and to the measurement of particle number, size, optical properties, and mass. Optical and electrical detection techniques are presented for particle number measurements. An overview of particle light scattering and absorption measurement methods is given. Various measurement principles for determining particle size are introduced, including those based on the optical interaction, aerodynamic behavior, or electrical mobility of particles. Particle mass measurement methods include gravimetric analysis, the vibration of a piezoelectric crystal, harmonic oscillation, and the attenuation of beta radiation. This chapter introduces sensors for measuring particle number, size, light scattering and absorption, and mass, while analysis of the chemical composition of particles will not be covered. General aspects of calibration and quality control are also described, typical technical specifications of the instrumentation are given, and recommendations for the maintenance of atmospheric particle sensors are presented. Finally, the chapter provides examples of applications and current developments in particle measurement techniques.