Coordinated Laboratory and Field Research on the Sources, Distribution, and Prediction of Atmospheric Ice Nucleating Particles (Invited Presentation)

The role of aerosol particles for primary ice formation in clouds contributes one of the largest uncertainties in understanding and predicting the Earth’s weather and climate systems. This uncertainty is related to the poor knowledge of ice nucleation microphysics as well as the nature and atmospheric abundance of ice nucleating particles (INPs). During the recent years, new laboratory methods have been developed and used for detailed experiments on the heterogeneous ice nucleation of various aerosol types, and mobile instruments were developed for measuring the concentration, size and chemical composition of INPs and ice residuals. Both laboratory and field observations provided the basis to develop new formulations and parameterizations for primary ice formation in cloud, weather and climate models.

In order to develop and maintain high standards for ice nucleation research, several intercomparison studies, laboratory experiments and field campaigns have been organized under the umbrella of the German research unit INUIT, funded by the German Science Foundation (DFG), and the three-part Fifth International Ice Nucleation (FIN) workshop series, funded by the U.S. National Science Foundation (NSF) and the Department of Energy (DOE). The INUIT and FIN activities addressed not only instrument and intercomparison issues, but also important science topics like the nature of atmospheric INP and cloud ice residuals, the ice nucleation activity of relevant atmospheric aerosols, or the parameterization of primary ice formation in atmospheric weather and climate models.

This contribution will summarize results from  (1) the INUIT laboratory intercomparison studies with Snomax, illite and cellulose, (2) the INUIT closure studies between model predicted and observed INP concentrations, (3) the INUIT field campaigns on INPs and ice residual measurements at the Jungfraujoch research station in Switzerland and in Cyprus, (4) the FIN-1 single particle mass spectrometer intercomparison study conducted in November 2014 at the AIDA facility in Karlsruhe, Germany, (5) the FIN-2 INP activity conducted during March 2015 at the AIDA facility with nine mobile INP instruments directly sampling from the AIDA aerosol chambers and several sampling methods for wet suspensions and filter samples or INP measurements, and (6) the FIN-3 activity conducted during September 2015 at the Desert Research Institute’s Storm Peak Laboratory (SPL) in Steamboat Springs, CO.

The results from these major international activities clearly underline the progress achieved during recent years for laboratory and field observations of heterogeneous ice nucleation and ice nucleating particles, but will also outline gaps, uncertainties and future needs in these research areas.

Major contributions from the INUIT and FIN participant teams are greatly acknowledged.