The Single Particle Soot Photometer (SP2) is manufactured by Droplet Measurement Technologies (DMT). It measures the soot (also known as black carbon) content of individual airborne particles, known as aerosols.

The SP2 is a laser-based instrument, which detects black carbon particles by heating them to their point of 'incandescence'. This results in the emission of radiation that can be measured and related to the mass of black carbon.

The instrument can be operated in a range of environments (lab, ground-based, aircraft) and its high sensitivity and fast response makes it ideal for a number of atmospheric science applications. The measurement frequency of this instrument is 1Hz.

The outputs include: black carbon mass, number and size; as well as information relating to the mixing state of black carbon-containing particles. Number and volume concentration of scattering particles; as well as their optical size are also included.

Black carbon is an important component of atmospheric aerosol and is a strong absorber of solar radiation. It is a product of incomplete combustion activities and the major sources include vehicle engines, burning of domestic fuels for heating/cooking and forest/agricultural fires. Human activities have increased the amount of black carbon in the atmosphere, which leads to a warming of the Earth's temperature.

This instrument is regularly used on the FAAM BAe 146 aircraft.