The effect of human activities on climate is a grand challenge facing society today. Humans influence climate in many ways. Emissions of greenhouse gases (GHGs) tend to warm climate, by reducing the amount of infrared radiation that is emitted to space. Increased levels of suspended atmospheric particles (“aerosols”) exert a net cooling effect by directly scattering and absorbing of incoming solar radiation. Aerosols also affect clouds by acting as the seed for droplet (or ice crystal) formation. “Seeding” of clouds by anthropogenic pollution is thought to cool climate by modulating cloud reflectivity and development. Aerosol variations have also been proposed to affect the development of storm systems, precipitation and the hydrological cycle overall. Quantitatively constraining aerosol impacts on clouds and climate however is very uncertain and significantly affects predictions of climate sensitivity to GHG levels. The large uncertainty originates largely from the complex and multi-scale coupling of aerosols and clouds. Added to this complexity is the large variability and range of aerosol types, each of which is characterized with its own ability to nucleate droplets and ice crystals.
Our research focuses on advancing the description of aerosols and aerosol-cloud interactions in atmospheric models through the combination of observations, theory and modeling. We have developed physical relationships that efficiently and accurately predict aerosol thermodynamics and the formation of droplet and ice crystal formation in models. We also have developed advanced tools to understand the sensitivity of predicted aerosol and cloud fields to their input. Modeling efforts also include understanding the climate impacts of aerosol, dynamical downscaling of climate model simulations as well as land use modeling and land-atmosphere coupling. Our group also focuses on the development of aerosol instrumentation, measurement techniques for understanding the aerosol-cloud link and aerosol properties, such as hygroscopicity, volatility and water uptake kinetics. We are also heavily involved in field measurement programs (both ground-based as well as airborne) focused on understanding the climate and health impacts of ambient aerosol from a wide variety of sources. We continuously try to expand into other areas of research, and are involved in a number of exciting exploratory projects, some of which are outlined below.
Last modified: July 25, 2014