Secondary ice processes: A modulator of global mixed-phase clouds

In-situ observations of mixed-phase clouds (MPCs) regularly reveal that ice crystal number concentrations (ICNCs) are orders of magnitude higher than ice-nucleating (IN) particle concentrations. This discrepancy has often been attributed to the influence of missed IN sources and secondary ice production (SIP) processes, but only recently considerable work has been invested towards better understanding the role of SIP. Here we present an overview of the main SIP processes and impacts that have been identified for globally-important cloud types (including polar, orographic and other cloud systems), and preset efforts to parameterize and study their impacts through a combination of observations and simulations for a variety of case studies over the years. An emphasis will be placed on what has been learned and what critical knowledge gaps remain for weather-prediction and climate models.

About Prof. Nenes

Athanasios Nenes is a Professor of Atmospheric Processes and heads the Laboratory of Atmospheric Processes and their Impacts (LAPI) at the École Polytechnique Fédérale de Lausanne, Switzerland. He is an affiliate researcher of the Institute of Chemical Engineering Science at the Foundation for Research and Technology Hellas in Patras, Greece and a founding member of the Center of Studies on Air quality and Climate Change at the institute. His research focuses on the impact of atmospheric processes (especially aerosol) on clouds, climate, air quality and ecosystems. He is the prime author of the ISORROPIA aerosol thermodynamics models, aerosol-cloud interaction parameterizations, and developer of instrumentation to measure aerosol properties and Cloud Condensation Nuclei. He is a Web of Science Highly Cited Researcher (2022,2021,2020), having authored/co-authored 343 manuscripts (Google Scholar citations: 34100, h=96). He serves as deputy President of Atmospheric Sciences of the European Geophysical Union (EGU) and co-Chair of its Annual Assembly, is a member of the UN Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (WG38: Atmospheric input of chemicals to the ocean), and served on the US National Academies Committee on the Future of Atmospheric Chemistry Research, Secretary of Atmospheric Sciences of the American Geophysical Union (AGU) and Editor in the Copernicus journal Atmospheric Chemistry and Physics. He is a Fellow of the AGU and the American Association for Aerosol Research (AAAR); he is also member of the Academia Europaea. Distinctions include the Copernicus Medal, ERC Consolidator Grant, AGU Ascent Award, AAAR Whitby and Friedlander Awards, American Meteorological Society Houghton Award; NASA New Investigator Award and a US National Science Foundation CAREER Award. He has mentored over 20 PhD students and 20 postdocs.