Airborne Observations of Regional Variations in Fluorescent Aerosol Across the U.S.

Wednesday, 17 December 2014: 8:30 AM
Anne Elizabeth Perring1, Joshua Peter Schwarz1, Darrel Baumgardner2, Mark Hernandez3, Dominick V Spracklen4, Colette L Heald5, Ru-Shan Gao6, Gregory L Kok2, Gavin McMeeking2, James B McQuaid4 and David W Fahey1, (1)NOAA ESRL, Boulder, CO, United States, (2)Droplet Measurement Technologies, Boulder, CO, United States, (3)Department of Civil, Environmental and Architectural Engineering, UC Boulder, Boulder, CO, United States, (4)University of Leeds, Leeds, United Kingdom, (5)Massachusetts Institute of Technology, Civil and Environmental Engineering, Cambridge, MA, United States, (6)NOAA Earth System Research Lab, Boulder, CO, United States
Airborne observations of fluorescent aerosol were made aboard an airship during CloudLab, a series of flights that took place in September and October of 2013 and covered a wide band of longitude across the continental US between Florida and California between 28 and 37N latitude. Sampling occurred from near the surface to 1000 m above the ground. A Wide-band Integrated Bioaerosol Sensor (WIBS-4) measured concentrations of supermicron fluorescent particles with average regional concentrations ranging from 1.4±0.7 to 6.8±1.4 x 104 particles m-3 and representing up to 24% of total supermicron particle number. We observed distinct variations in size distributions and fluorescent characteristics in different regions, and attribute these to geographically diverse bioaerosol populations. Fluorescent aerosol signatures detected in the east is largely consistent with those of mold spores observed in a laboratory setting. A shift to larger sizes associated with different fluorescent patterns is observed in the west. Loadings in the desert west were nearly as high as those near the Gulf of Mexico, indicating that bioaerosol is a substantial component of supermicron aerosol both of these humid and arid environments. The observations are compared to simulated fungal and bacterial loadings. Good agreement in both particle size and concentrations is observed in the east. In the west the model underestimates observed concentrations by a factor of 2 to 3 and the prescribed particle sizes are smaller than the observed bioaerosol.