Public Abstract

DE-SC0025196: Pristine Southern Ocean Aerosol and Cloud Processes: Coupling Single-Particle Measurements and Modeling during CAPE-k

Award Status: Active

Institution: Regents of the University of Michigan, Ann Arbor, MI
UEI: GNJ7BBP73WE9
DUNS: 073133571

Most Recent Award Date: 08/27/2024
Number of Support Periods: 1
PM: Stehr, Jeffrey

Current Budget Period: 09/01/2024 - 02/28/2026
Current Project Period: 09/01/2024 - 08/31/2027
PI: Pratt, Kerri

Supplement Budget Period: N/A

Public Abstract

Pristine Southern Ocean Aerosol and Cloud Processes: Coupling Single-Particle Measurements and Modeling during CAPE-k Kerri A. Pratt, University of Michigan (Principal Investigator) Christina McCluskey, National Center for Atmospheric Research (Co-Investigator) Andrew P. Ault, University of Michigan (Co-Investigator) Improving scientific understanding of aerosol-cloud interactions is critical to improving energy budget calculations for the atmosphere over the Southern Ocean. A key feature of Southern Ocean aerosol-cloud interactions is the uniquely pristine aerosol conditions, where the summertime marine near-surface atmosphere has little to no influence of continental and anthropogenic influences. The unique oceanic microbial community and biogeochemical processes of this pristine region define the atmospheric aerosol population that nucleates clouds, influencing cloud properties and precipitation. There is a dearth of in-situ Southern Ocean observations, limiting understanding of the large biases in climate model simulations compared to satellite observations and pointing to limited aerosol process understanding. The overarching objective of this project is to improve understanding and predictability of Southern Ocean aerosol concentrations, chemical composition, and sources, and their relationship to cloud condensation nuclei (CCN) and ice nucleating particles (INPs) that influence cloud droplet and ice crystal formation. This project will combine observations with modeling for the Apr. 2024 – Sep. 2025 DOE ARM Cloud and Precipitation Experiment at Kennaook (CAPE-k). Intensive atmospheric aerosol sampling of SO air masses will be conducted at Kennaook/Cape Grim, Tasmania, Australia from Feb. – Apr. 2025. Measurements of single-particle chemical composition, aerosol size distributions, CCN, and INPs will be used to assess aerosol simulated using the Community Atmosphere Model (CAM). These novel single-particle (0.03-10 µm) composition measurements (electron microscopy, Raman, photothermal infrared), in combination with additional ARM and Australian-led measurements, will enable identification of aerosol sources in Southern Ocean air masses that influence Southern Ocean clouds through their action as CCN and/or INPs. A key and novel component of the project will be the modeling (OCEANFILMS) and single-particle measurements (Raman microspectroscopy) of marine organic compounds that we hypothesize will be abundant and found as coatings on sea salt aerosol in the pristine Southern Ocean air masses. Overall, this project combines CAPE-k aerosol sampling and single-particle measurements, ARM data analyses, and modeling focused on CCN and INPs to vastly improve understanding of Southern Ocean aerosols and aerosol-cloud interactions. This project aims to contribute to the DOE ASR (Atmospheric System Research) Aerosol Processes and High Latitude Processes working groups by improving the understanding of the model representation of interactions between aerosol and clouds and therefore their impacts on the energy budget in the Southern Ocean region. This project will also include the development and leadership of an international CAPE-k aerosol science team. This CAPE-k project will contribute to PICCAASO (Partnerships for Investigating Clouds and the biogeoChemistry of the Atmosphere in Antarctica and the Southern Ocean), an international initiative to “amplify the scientific discovery of…projects occurring in the Antarctic and Southern Ocean region by facilitating global collaboration and coordination”, with a specific focus on “scientific questions surrounding the link between biogeochemistry and atmospheric processes in this pristine region.” PICCASSO is an activity of the International Global Atmospheric Chemistry (IGAC) Project Southern Hemisphere working group and CATCH (Cryosphere and Atmospheric Chemistry) activity. This project also has relevance to the international Scientific Committee on Oceanic Research (SCOR) working group CIce2Clouds, which has the mission “to bring the sea-ice and atmospheric communities together to resolve open questions about the impacts of the marine cryosphere on atmospheric chemistry in the polar ocean environments.”

Pristine Southern Ocean Aerosol and Cloud Processes: Coupling Single-Particle Measurements and Modeling during CAPE-k
Kerri A. Pratt, University of Michigan (Principal Investigator)
Christina McCluskey, National Center for Atmospheric Research (Co-Investigator)
Andrew P. Ault, University of Michigan (Co-Investigator)

Improving scientific understanding of aerosol-cloud interactions is critical to improving energy budget calculations for the atmosphere over the Southern Ocean. A key feature of Southern Ocean aerosol-cloud interactions is the uniquely pristine aerosol conditions, where the summertime marine near-surface atmosphere has little to no influence of continental and anthropogenic influences. The unique oceanic microbial community and biogeochemical processes of this pristine region define the atmospheric aerosol population that nucleates clouds, influencing cloud properties and precipitation. There is a dearth of in-situ Southern Ocean observations, limiting understanding of the large biases in climate model simulations compared to satellite observations and pointing to limited aerosol process understanding.

The overarching objective of this project is to improve understanding and predictability of Southern Ocean aerosol concentrations, chemical composition, and sources, and their relationship to cloud condensation nuclei (CCN) and ice nucleating particles (INPs) that influence cloud droplet and ice crystal formation. This project will combine observations with modeling for the Apr. 2024 – Sep. 2025 DOE ARM Cloud and Precipitation Experiment at Kennaook (CAPE-k). Intensive atmospheric aerosol sampling of SO air masses will be conducted at Kennaook/Cape Grim, Tasmania, Australia from Feb. – Apr. 2025. Measurements of single-particle chemical composition, aerosol size distributions, CCN, and INPs will be used to assess aerosol simulated using the Community Atmosphere Model (CAM). These novel single-particle (0.03-10 µm) composition measurements (electron microscopy, Raman, photothermal infrared), in combination with additional ARM and Australian-led measurements, will enable identification of aerosol sources in Southern Ocean air masses that influence Southern Ocean clouds through their action as CCN and/or INPs. A key and novel component of the project will be the modeling (OCEANFILMS) and single-particle measurements (Raman microspectroscopy) of marine organic compounds that we hypothesize will be abundant and found as coatings on sea salt aerosol in the pristine Southern Ocean air masses.

Overall, this project combines CAPE-k aerosol sampling and single-particle measurements, ARM data analyses, and modeling focused on CCN and INPs to vastly improve understanding of Southern Ocean aerosols and aerosol-cloud interactions. This project aims to contribute to the DOE ASR (Atmospheric System Research) Aerosol Processes and High Latitude Processes working groups by improving the understanding of the model representation of interactions between aerosol and clouds and therefore their impacts on the energy budget in the Southern Ocean region. This project will also include the development and leadership of an international CAPE-k aerosol science team. This CAPE-k project will contribute to PICCAASO (Partnerships for Investigating Clouds and the biogeoChemistry of the Atmosphere in Antarctica and the Southern Ocean), an international initiative to “amplify the scientific discovery of…projects occurring in the Antarctic and Southern Ocean region by facilitating global collaboration and coordination”, with a specific focus on “scientific questions surrounding the link between biogeochemistry and atmospheric processes in this pristine region.” PICCASSO is an activity of the International Global Atmospheric Chemistry (IGAC) Project Southern Hemisphere working group and CATCH (Cryosphere and Atmospheric Chemistry) activity. This project also has relevance to the international Scientific Committee on Oceanic Research (SCOR) working group CIce2Clouds, which has the mission “to bring the sea-ice and atmospheric communities together to resolve open questions about the impacts of the marine cryosphere on atmospheric chemistry in the polar ocean environments.”