The various instruments at iap are briefly described below. You can also view the airplane system.


The nephelometer (TSI Model#3563) measures forward and backward scattering by aerosol particles at three wavelengths: blue (450 nm), green (550 nm) and red (700 nm).

Particle Soot/Absorption Photometer (PSAP)

The PSAP (Radiance Research) measures light absorption by particles at a single wavelength: green (565 nm).

Size and Relative Humidity Control

There is a 1 um impactor upstream of the nephelometer and PSAP. The impactor ensures that only fine particles, which are the dominant contributors to light scattering and absorption, are measured. Additionally, it is difficult to accurately sample larger (diameter > 1 um) particles at aircraft speed. The sample is heated, if necessary, to maintain the relative humidity at less than 40%.

Temperature/Humidity Sensor

The T/RH sensor (Vaisala 'Humicap') measures atmospheric temperature and relative humidity. The sensor is mounted inside a counterflow inlet on the bottom of the aircraft wing.

Drum Sampler

The DELTA group at UC Davis has a drum sampler on board to make size-segregated chemical measurements of the aerosol particles. The sampler has size cuts at 1 um, 0.56 um, 0.34 um and 0.07 um. Samples will be analyzed for elemental composition using PIXE-XRF and other analytical techniques.