Aircraft Measurements of Saharan Dust and Fluorescent Biological Particles and Implications for Ice Nucleation
Cynthia Twohy
Senior Research Scientist, NorthWest Research Associates
Visiting Researcher, Scripps Institution of Oceanography
Both mineral dust and some types of biological aerosol particles are known to nucleate ice in the atmosphere, with the potential to influence cloud microphysical properties and climate. Aircraft measurements of both types of particles were made in different meteorological regimes. The first half of the talk will focus on the interaction of Saharan dust with tropical convection over the Atlantic Ocean. In particular, we are investigating the impact of clouds on the Saharan Air Layer and how much dust is transported to the upper troposphere vs. how much is removed in precipitation. The removal and redistribution of dust by convection has important implications for direct and indirect radiative forcing, as well as for ocean biogeochemistry.
In the second half of the talk, vertical profiles of fluorescent biological aerosol particles using the Wideband Integrated Bioaerosol Sensor (WIBS-4A) will be presented. The WIBS-4A instrument was flown over the U.S. Great Plains region during the NSF IDEAS-2013 test campaign. Clear-air profiles showed a strong dependence of biological particles on altitude (or temperature), but much intra- and inter-flight variability. Some ice nuclei temperature spectra were also measured with offline analyses of filters. A preliminary assessment of the importance of biological aerosol particles for ice nucleation in mixed-phase clouds in the region will be discussed.
Seminar will be webcast at: http://www.fin.
Tuesday, 3 May 2016, 3:30 PM
Refreshments 3:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg 2 Main Auditorium (Rm1022)
