Environmental & Climate Sciences Department Seminar

Atmospheric aerosols directly affect the earth's energy balance through the scattering and absorption of solar radiation. While aerosols are expected to have a net negative forcing (i.e. cooling), the actual magnitude of this effect remains highly uncertain due to physical, chemical, spatial and temporal variability. To complicate matters, strongly absorbing carbonaceous aerosols (i.e. black carbon, BC) exhibit a positive radiative forcing rivaling methane. A better understanding of the magnitude of these aerosol-radiation interactions requires a multi-pronged approach with fundamental metrology (e.g. instrumentation, methods, standards and calibrations) utilizing well-characterized systems under controlled conditions representing just one piece of the puzzle. Highlights of recent projects at the National Institute of Standards and Technology (NIST) will be presented including: 1) the characterization and use of a water-stabilized carbon black (CB) nanomaterial that mimics aged BC that can be used to calibrate aerosol instrumentation, 2) results from the first-ever photoacoustic spectrometer intercomparison study, 3) variability in the aerosol absorption spectra of highly-absorbing carbonaceous aerosols from a variety of sources and 4) aerosol absorption spectra of terrestrial mineral dusts and Martian soil simulants.