Towards Aerosol-Ice Formation Closure – Chemical Imaging Investigation of Aerosol and Ice Nucleating Particles
EMSL Project ID
60345
Abstract
Prediction of ice nucleating particle (INP) number concentrations from ambient aerosol particles represents an urgent and challenging issue when simulating cloud processes in climate models. A recent field campaign aerosol – ice formation closure pilot study emphasized the need for better quantification of the role of soil-dust particles serving as atmospheric INPs. Prediction of INPs from ambient aerosol was partially successful, however, impeded by the lack of quantitative INP prediction from agriculturally derived soil-dust particles. Soil-dust particles are physicochemically complex containing inorganic, organic, and biological matter, where it has been demonstrated previously that the organic and biological soil-dust fraction can enhance INP number concentrations by immersion freezing. However, the ice-nucleating agents associated with soil-dust particles have yet not been identified. This fact impedes the development of more accurate physical models and parameterizations of immersion freezing that cloud-resolving and climate models depend on to perform reliable simulations of the Earth system and energy budget. To advance our understanding of atmospheric ice formation, we conducted AIDA (Aerosol Interactions and Dynamics in the Atmosphere) cloud chamber experiments in June/July 2021 to examine in detail the immersion freezing efficacy of soil-dust particles. These AIDA cloud chamber experiments allowed us to examine soil-dust aerosol particles before and during ice cloud formation. Compared to the field, these experiments were conducted for a longer period under simulated ambient conditions yielding the collection of larger analytical samples and data sets that result in improved closure calculations. Furthermore, the AIDA facility enabled the collection of ice crystal residuals that represent the activated INPs, allowing for a unique opportunity to identify INPs and relate those to the overall soil-dust particle population. Hence, we can directly evaluate our predictive capability of the fraction of soil-particles acting as immersion freezing INPs. This goal is directly relevant to the missions of DOE BER and the EMSL User Facility to advance our predictive understanding of the dynamic processes needed to model the Earth system.
The overarching objective of this proposal is to apply chemical imaging (CI) investigation to identify the physicochemical properties associated with soil-dust particles that make up the INPs in this particle population. CI will yield the necessary information about size-resolved chemical composition to achieve ice formation closure with important implications for INP prediction in cloud and climate models.
EMSL/PNNL provides unique micro-spectroscopic single-particle analytical techniques and high-resolution mass spectrometric techniques to examine the physicochemical characteristics of aerosol particles and INPs in the nm-to-μm size range and resolve associated molecular signatures in the particulate phase. This analytical capability will be vital for achieving aerosol – ice formation closure and will allow us to develop ice nucleation parameterizations that produce the most robust predictions of INP number concentrations and thus are best suited to be included in cloud and climate models.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2022-10-01
End Date
N/A
Status
Active
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members