Spectro-Microscopic Investigation of the Aerosol Impact on Hydrological Processes

This project will investigate combined physical and chemical properties of atmospheric particles collected during field campaigns, organized and managed by the Atmospheric Radiation Measurement (ARM) program of the Department of Energy, and how these airborne particles are involved in the water cycle. We will focus our efforts on comprehensive chemical imaging and molecular characterization of particles collected during the Surface-Atmosphere Integrated Field Laboratory (SAIL) and the Tracking Aerosol

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

Convection Interactions ExpeRiment (TRACER) campaigns.  We will examine elemental and molecular composition, mixing state, size, and internal structures of individual particles, along with molecular-level characterization of complex light-absorbing organic constituents in bulk aerosol and snow samples (from SAIL campaign). By combining our analyses with concurrent trace gases, meteorological, cloud, and in-situ aerosol measurements, we will investigate relevant aerosol regimes, aerosol-precipitation interactions, and changes in surface energy balance induced by snowpack deposits. Our measurements will be used to evaluate particle propensity to serve 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

(CCN) and ice nucleating particles

ice nucleating particles

Tiny specks of material suspended in the air that act as starting points for the formation of ice crystals in clouds.

Source: Pacific Northwest National Laboratory Source

(INP), assess aerosol radiative properties, and the link between snowpack albedo and atmospheric deposition of particulate matter. Our specific goals for the SAIL campaign are:  (1) Characterize aerosol regimes and sources, identify particle-type populations, mixing states, and atmospheric transformations based on the statistical analysis of our detailed measurements and the real-time records of the ARM operated Mobile Aerosol Observing System deployed in the field and additional measurements available from other research groups participating in the SAIL experiment; (2) Quantify the optical and chemical properties of snowpack deposits to investigate how aerosol deposition influence snowpack lifetime; (3) Link the chemical and optical properties

optical properties

The characteristics of a material that define how it interacts with light.

Source: Source

of aerosols and snowpack deposits to determine impacts on the radiative forcing of climate from its atmospheric and surface components. Successful completion of these objectives will advance scientific understanding of aerosols regimes, sources, aerosol-precipitation interactions, and atmosphere-land interactions.

In the TRACER study, we will provide chemical imaging insights into the particle-type composition and particle mixing states informing interpretation of hygroscopicity

hygroscopicity

The ability of a particle to take up moisture from the environment and is important for understanding the ability of particles to act as cloud condensation nuclei (CCN).

Source: ARM Source

parameters inferred from the real-time measurements of size-resolved CCN spectra and from the growth factors determined from relative humidity (RH)-controlled particle size distributions. We will provide comprehensive microscopic characterization of individual particles necessary to understand and quantify variations and differences in the values of hygroscopicity parameters for aerosols of representative compositions and sources. In turn, application of the better constrained values of those hygroscopicity parameters in atmospheric models will advance predictions of aerosol effects on formation of clouds and their life cycles. We will also investigate the effects of particle composition and mixing states on the integrated optical characteristics of aerosol measured by filter-based techniques. Currently employed filter-based measurements of aerosol 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

are strongly influenced by many factors (e.g., filter type, location of particles on the filter, particle composition, mixing state and morphology,

morphology

The science of the form and structure of organisms (plants, animals, and other forms of life).

Source: National Cancer Institute Source

etc.) that typically result in absorption enhancement due to multiple scattering from the filter medium and deposited particles. Existing corrections for retrieval of atmospheric aerosol optical properties from filter-based measurements were derived from simplified reference materials which are not universally applicable to real-world aerosol mixtures. Our chemical imaging measurements of particles from the TRACER campaign will inform new observation-based corrections for improved retrieval of aerosol optical properties from filter-based measurement techniques, validating their results and associated errors.

In addition, a quantitative

quantitative

Data represented numerically, including anything that can be counted, measured, or given a numerical value.

Source: National Library of Medicine Source

description of particles’ mixing state using will allow for a meaningful comparison with the particle-resolved process models capable of simulation of gas-particle partitioning, atmospheric aging

atmospheric aging

Refers to the gradual alteration of atmospheric constituents, including gases and aerosols, through chemical, physical, and biological processes over time.

Source: Source

of aerosols on local and regional scales, and corresponding changes in their optical and cloud-forming properties. In turn, calculations by the process models will serve as an input for the Community Earth System Model

earth system model (ESM)

A model that simulates how chemistry, biology, and physical forces work together. These models are similar to, but much more comprehensive than, global climate models.

Source: U.S. Department of Energy Source

and by extension to DOE's Energy Exascale Earth System Model (E3SM)

Energy Exascale Earth System Model (E3SM)

The Energy Exascale Earth System Model (E3SM) project includes Earth System Models, simulations, and predictions to investigate energy-relevant science using code optimized for DOE's advanced supercomputers.

Source: NVCL Web Page Source

to evaluate the mass and number concentrations of different particle types at regional-to-global scales, and their impact on direct and indirect radiative forcing of climate.