Seminar

Abstract

Atmospheric aerosols affect climate by direct scattering of solar radiation and by altering cloud properties. Current uncertainties in anthropogenic aerosol forcing are one of the largest factors in total uncertainties in predicting climate change. In situ measurements of the properties, origins and climatic relevance of aerosols are needed to constrain global climate models, validate satellite measurements and better understand aerosol sources and processing in the atmosphere. In situ measurements of aerosol in the remote free troposphere have hitherto been particularly sparse.

The Atmospheric Tomography Mission (ATom) is a unique set of measurements characterizing the remote free troposphere. ATom uses the NASA DC-8 as a flying lab, equipped with gas phase and aerosol measurements, flying over both Pacific and Atlantic Ocean basins, with near pole-to-pole coverage, constantly scanning between 0.2 and 13km altitude. Measurements are conducted in all four seasons to capture seasonal variations.

We describe the measurement of aerosol size distributions from 3 to 3000 nm diameter on ATom, how these measurements inform our understanding new particle formation in the remote atmosphere, and how these particles influence climate. We compare our data from ATom with the GEOS-Chem global chemical-transport model with online TOMAS aerosol microphysics.

---

Christina Williamson is a research scientist at the NOAA Chemical Sciences Division, working in the Cloud and Aerosol Processes Group. She earned a Master's Degree in Physics at the University of Oxford, and a Ph.D. in Atmospheric Sciences and Meteorology at Goethe University studying aerosol nucleation and growth. She began work at NOAA in 2015, where her research has focused on aerosol measurements during the Atmospheric Tomography Mission (ATom).