LAACI ¿ Light Absorbing Aerosol-Cloud Interactions Experiment

Atmospheric light-absorbing aerosols,

aerosols

Small particles or droplets, such as wildfire smoke, volcanic gases, or salty sea spray, that float in the air. They are emitted by both natural events and human activities.

Source: NASA Global Climate Change Source

especially black carbon-containing particles, significantly impact the Earth’s radiation budget through direct radiative forcing (i.e., light absorption

absorption

The mechanism through which energy (e.g., solar or infrared) is converted into heat and contributes to the overall warming of the Earth's atmosphere and surface.

Source: NOAA Source

and scattering), indirect effects by interactions with clouds, and semi-direct effects by altering atmospheric dynamics.  Morphological changes of black carbon

black carbon

The sooty black material emitted from gas and diesel engines, coal-fired power plants, and other sources that burn fossil fuel. It comprises a significant portion of particulate matter or PM, which is an air pollutant.

Source: EPA Source

and encapsulation within other aerosol material affect the particles' scattering and absorption cross-sections, a process that has been the subject of several studies led by the Department of Energy to reduce direct radiative forcing uncertainties. However, significantly less work has focused on the interactions of black carbon-containing particles with clouds, and thus many important questions remain open. With this project, we aim to fill key gaps in our understanding of the interactions of black carbon-containing particles with clouds, including how these interactions drive direct and indirect radiative forcing, modify cloud microphysical properties, and govern the particles’ wet removal. To achieve these objectives, we plan to examine the optical, physical, and chemical properties of black carbon-containing particles in clouds under controlled laboratory conditions. We plan to participate in planned experiments at Brookhaven National Laboratory, and to lead a series of experiments in a turbulent cloud chamber at Michigan Technological University to examine the cloud processing of two extreme types of black carbon-containing particles: nascent (i.e., recently emitted) and thickly-coated (i.e., atmospherically aged).

In particular, we plan to tackle questions on how black carbon-containing particles participate in aqueous-phase/cloud-chemistry, how that affects the particles' physical, and chemical properties, how that affects their ability to act as cloud condensation nuclei,

cloud condensation nuclei

Tiny airborne particles suspended in the atmosphere that serve as the seeds around which cloud droplets form.

Source: Source

and how that affects their lifetime in the atmosphere. We will also focus on the effects that black carbon-containing particle properties have on the cloud properties and the role of turbulence in cloud-aerosol as well as aerosol-cloud interactions.

aerosol-cloud interaction

The interaction of airborne particles (aerosols) with clouds. Scientists study how aerosols affect clouds and how these interactions can impact the Earth's climate.

Source: DOE Source

The overarching goal of this project is to provide climate models with data to drive a new generation of parameterizations specifically developed to address and improve the fidelity of numerical simulations of the interactions between black carbon-containing particles and clouds, and accounting for the effects of aerosol atmospheric aging and turbulence. To achieve this goal, as an integral part of the project, we plan to work in close collaboration with modeling experts running cloud-parcel and particle-resolved models.