What do we do? Why does it matter?
aerosol Particules in the atmosphere (aerosol) are everywhere, although they are too small to be seen with the naked eye (about hundreds ~ thousands of times smaller than the width of a hair). Some are emitted from sources as is (primary particles, e.g., dusts); some are produced in the atmosphere through chemical reactions (secondary particles, e.g., ammonium sulfate); some are alive or once alive (bioaerosol).

Do aerosol help us or harm us? It's complicated. They are air pollutant (e.g., PM2.5); however, without aerosol, there will be no clouds (water needs something to condense onto). They act as a sunshade by reflecting some sunlight back into space, as well as seeding clouds. The cooling effect by aerosol is estimated to mask approximately half of the warming effect by green house gases (with a large uncertainty) (IPCC 2007, 2014).

We work on the fundamental questions at the interface of air quality and climate:
  • - How are aerosols formed?
  • - How are cloud droplets formed?
  • - How do aerosol and cloud influence each other?

We use and develop unique experimental techniques to better understand the role of aerosol in the atmosphere.