Integrating Nephelometer

The Integrating Nephelometer provides long-term monitoring of air quality in ground-based and airborne studies. It continuously monitors the light scattering coefficient of airborne particles.

The nephelometer is an instrument that measures aerosol light scattering. It detects scattering properties by measuring light scattered by the aerosol and by subtracting light scattered by the gas, the walls of the instrument and the background noise in the detector. The integrating nephelometer splits the scattered light into red (700 nm), green (550 nm), and blue (450 nm) wavelengths and measures back-scattered light at these wavelengths, as well.

The nephelometer has three operating wavelengths (450, 550 and 700 nm) and a 40 nm bandwidth for all wavelengths. The sensitivity at 30 sec averaging time is 1x10-7 m-1 for blue and green and 3x10-7 m-1 for red wavelength. The averaging time is selectable between 1 and 4096 sec and the response time below 20 sec. The particle transport efficiency is over 95% of unit-density particles from 0.05 to 5 μm in diameter.

The output data can be grouped in 4 categories: time records (record the time of measurement), photon count records (measures photon counts form calibrator, measure and dark), data record (give scattering coefficients for the three wavelengths) and auxiliary status record (with data from sensors and supply statistics).