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Aerosol Life Cycle
The primary objective of ASR's Aerosol Life Cycle Working Group research is to understand and quantify the processes associated with the aerosol life cycle, the direct impact of aerosols on the Earth’s radiative balance, and the nature and distribution of cloud condensation nuclei with the goal of improving their representations and thereby reducing the uncertainty in global and regional climate simulations and projections.
To this end, the working group addresses integrated chemical, physical and radiative processes from emissions, nucleation, transport, and ageing to removal. We seek an understanding of the impact of these processes on the spatial and temporal distributions of global aerosol, the natural versus anthropogenic attribution of aerosol, and the relationship among physicochemical, cloud activating, and optical properties of aerosol. To understand and efficiently represent these processes at all pertinent scales, the ALWG will employ in situ and remote sensing observations from surface-based, airborne and satellite platforms from the process-level to the global scale, together with laboratory studies and modeling efforts.
The ALWG strives to answer questions relevant to the aerosol life cycle that will advance process understanding and model representation at a range of scales from the smallest-scale mechanisms (e.g., new particle formation) to large-scale phenomenon (e.g., global radiative balance). In working within any of the Science Foci outlined here, questions are formulated in a manner that will concurrently further knowledge within one or more of the overarching Research Themes presented below. Our objective is to produce integrated information that is readily useable in climate prediction.
Geographical Distribution of Aerosol
Defining the spatial (horizontal and vertical) and temporal variability of aerosol properties and radiative forcing with reduced uncertainty will provide better observational estimates of aerosol direct and indirect radiative forcing and improvement in modeling these quantities.
Natural vs. Anthropogenic Aerosol
Understanding the contribution of anthropogenic aerosol to the total aerosol is required for determining aerosol radiative forcing. This will require comprehensive understanding of emissions and their sources, life cycle processes, and the resulting aerosol radiative properties.
Scale in Observations and Representation of Aerosol
Understanding the relationship of scale to physical processes is required to improve observational accuracy and to further development of parameterizations that are designed to be less sensitive to model scale.
New Particle Formation, Aerosol Aging and Removal
- New particle formation and particle growth rate
- SOA formation (gas-phase and aqueous-phase)
- Cloud processing of aerosol (aqueous-phase chemistry, droplet coalescences, and wet removal)
- Variation of aerosol properties (size, composition, and mixing state, and distribution) during aerosol aging
- Dry deposition
- Simplified representation of aerosol properties (composition and mixing state) and processes
Nucleating Properties for Water and Ice Containing Clouds
- Role of aerosol size, composition, and mixing state on CCN spectrum
- Aerosol properties that determine ice nuclei (IN) concentration as a function of supersaturation
- Influence of aging on cloud nucleating properties of aerosols
Direct Radiative Impacts
- Determining aerosol optical properties from particle size, morphology, mixing state, and composition
- Quantifying and parameterizing the dependence of aerosol optical properties on relative humidity
- Influence of aging on aerosol optical properties (e.g. black carbon particles)
- Role of absorbing aerosol on heating rate profiles, atmospheric circulation, cloud development, and precipitation