AGS-firp track 2: aerosol-mixed phase cloud interactions through cloud chamber experiments

The National Science Foundation awarded San Jose State University Research Foundation $374,521 on July 1, 2026, under the Geosciences program (CFDA 47.050, AGS-FIRP Track 2) to conduct cloud chamber experiments investigating aerosol-mixed phase cloud interactions.

The project will generate multiple steady-state mixed-phase clouds using varying concentrations of cloud condensation nuclei and ice nucleating particles across different temperature gradients in Michigan Tech University's PI Cloud Chamber. The work addresses two primary research questions: how ice and supercooled liquid water particle size distributions respond to different CCN and INP concentrations, and how ice integral radius values required to glaciate mixed-phase clouds respond to different temperature and water vapor flux forcing. The research will analyze the impacts of aerosols and turbulence on cloud behavior under controlled laboratory conditions. Findings are intended to improve precipitation forecasts and provide data relevant to aircraft icing studies.

Performance occurs in San Jose, California, with work extending through June 30, 2029. Sub-awards are planned for this project.

Abstract

Clouds that contain liquid and ICE simultaneously are known as mixed-phase clouds. These clouds play an important role in the formation of precipitation and control of sunlight reaching the surface. A significant uncertainty with mixed-phase clouds is how they respond to aerosols, which are small atmospheric particles such as dust. This project will conduct a series of experiments in a specialized laboratory instrument known as a cloud chamber. Better representation of mixed-phase clouds will improve precipitation forecasts and provide important information for studies of aircraft icing. This project will consist of experiments in the michigan tech university?s PI cloud chamber to investigate the sensitivity of mixed-phase cloud microphysics to aerosol and thermodynamic perturbations. Multiple steady-state mixed-phase clouds will be generated using varying concentrations of cloud condensation nuclei (CCN) and ICE nucleating particles (INP), and different temperature gradients, to analyze the impacts of aerosols and turbulence on clouds under controlled laboratory conditions. The primary research questions are to determine: 1) how ICE and supercooled liquid water particle size distributions in mixed-phase clouds respond to different initial CCN concentrations and INP concentrations, and 2) how do the ICE integral radius values required to glaciate the mixed-phase cloud respond to different temperature and water vapor flux forcing? This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the foundation's intellectual merit and broader impacts review criteria.- subawards are planned for this award.