The Single Particle Soot Photometer is on the lower left in the aircraft pallet.
Photo courtesy David Fahey.
Tools of the trade
Everything you need to seek out soot
To precisely measure atmospheric soot levels, David Fahey’s team custom built an autonomous device—a single particle soot photometer—that selectively measures only black carbon particles and their coatings. They mounted the device into the belly or cabin of three types of planes: NASA’s WB-57F high-flier (which cruises above 19km), the NSF NCAR GV long-range jet (16km) and NOAA’s WP-3D “Hurricane Hunter” (6km). An inlet outside the aircraft brings air into the photometer where a laser zaps the sample with infrared light. “Black carbon particles absorb the radiation, heat up and emit light, like an electric heater glowing red, until they vaporize at about 4,000 Kelvin,” Fahey said. Since black carbon is the only atmospheric aerosol known to absorb infrared wavelengths with high efficiency, measurements of the emitted light reveal the quantity and size of black carbon particles present.
