Collaboration with the ARM and EMSL Facilities to Study the Composition and Hygroscopicity Relationship in Atmospheric Aerosols.

Collaboration with the ARM and EMSL Facilities to Study the Composition and 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

Relationship in Atmospheric 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

Haofei Zhang, University of California, Riverside

Atmospheric aerosols play important roles in the climate system and radiative budget; they are the largest individual source of uncertainty in assessing the Earth’s radiative balance.

radiative balance

Radiation Balance is the energy balance between incoming energy from the Sun and outgoing energy from the Earth.

Source: National Oceanic and Atmospheric Administration Source

One way that aerosols impact the climate system is by forming clouds, which is closely related to aerosol hygroscopicity. Atmospheric aerosol particles are ubiquitously comprised of both inorganic and organic species, which together determine aerosol hygroscopicity. The inorganic substances in aerosols as well as their hygroscopic properties are well known, while the organic compositions and their hygroscopicity remain largely unclear. Organic material accounts for about 20 – 80% of total aerosol mass in the atmosphere and thus play a key role in aerosol hygroscopicity. But they are present in the form of hundreds to thousands of individual species, among which only a few substances and mixtures have been investigated with hygroscopicity measurements. Thus, understanding the composition–hygroscopicity relationship in atmospheric aerosols is extremely challenging.

In this RDPP project, the PI aims to collaborate with two BER-EESSD user facilities, ARM and EMSL, to understand the aerosol composition and hygroscopicity relationship. The Southern Great Plains (SGP) observatory operated by the ARM facilities is one of the very few sites in the world that have long-term simultaneous monitoring of aerosol bulk chemical composition (by an aerosol chemical speciation monitor) and hygroscopicity (by a cloud nucleation condensation counter and a humidified tandem differential mobility analyzer). In the first objective of the project, the PI plans to explore the long-term aerosol hygroscopicity data along with the bulk aerosol composition. To aid elucidate the implicit and highly complex relationship between aerosol composition and hygroscopicity, positive matrix factorization (PMF) analysis will be applied. In the second objective of the RDPP project, the PI plans to establish a partnership with the EMSL facility and demonstrate the unique capabilities of complementary mass spectrometry

mass spectrometry (MS)

Mass spectrometry (MS) is an analytical technique that separates ionized particles such as atoms, molecules, and clusters and can be used to determine the molecular weight of the particles.

Source: National Library of Medicine Source

analysis of aerosol molecular composition. It has been shown that there is a large uncertainty in aerosol hygroscopicity estimate when using bulk aerosol chemical parameterization (i.e., elemental oxygen-to-carbon ratio). Therefore, laboratory-generated aerosols will be analyzed using a suite of mass spectrometry techniques available in the PI’s laboratory (e.g., the ion-mobility spectrometry time-of-flight mass spectrometer) and at the EMSL facility (e.g., the nanospray desorption electrospray ionization coupled to the Orbitrap mass spectrometer, or the Fourier transform ion cyclotron resonance mass spectrometer). This collaboration will lead to improved molecular-level and isomer-level understanding of aerosol composition and can be applied in future atmospheric aerosol analysis.

The RDPP project will initiate collaborations with the EESSD user facilities and provide a unique opportunity for the PI to expand his research capabilities in atmospheric science. The PI also plans to visit the ARM-SGP and EMSL user facilities and attend EESSD programmatic meetings through the support of the RDPP award, to meet EESSD scientists and develop new partnerships in broader atmospheric science topics. Further, the EESSD data obtained from this collaboration work will be incorporated into the environmental and atmospheric chemistry courses that the PI teaches at the University of California, Riverside.