Seminar

Abstract

The current quiescent volcanic period, from 2000 to 2010, has provided a unique opportunity to observe the background state of stratospheric aerosols. Observations of aerosol backscatter from Rayleigh/Mie lidars located in Lauder, New Zealand, Mauna Loa, Hawaii and Boulder, Colorado during this period are explored with an emphasis on understanding the decadal trends in the stratospheric aerosol layer. This analysis shows an increasing trend in the backscatter cross-section over the last decade at all three sites that is modulated by a strong seasonal cycle with a winter maximum. To further understand the differing roles of transport, chemical and microphysical processes of the aerosol layer, the results of the lidar data analysis are compared to output from the Whole Atmosphere Community Climate Model coupled to the Community Aerosol and Radiation Model for Atmospheres that has been structured to include sulfate aerosols and meteoritic dust and various emission scenarios, including anthropogenic emissions and moderate volcanic injections observed from 2000 to 2010. This seminar will focus on modeling results that suggest the observed trends are largely due to volcanic injections but anthropogenic emissions may still have some impact. I will discuss how the fusion of modeling and lidar backscatter retrieval analysis led to improvements in retrievals of stratospheric aerosols made by current Rayleigh/Mie lidars.