In situ measurements of ice nucleating particles (INP) and quantification of biological INP

• Applicant: Professor Dr. Joachim Curtius, since 9/2017
• Subject Area: Atmospheric Science
• Term: from 2011 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 170852269

Understanding the formation of ice in the troposphere is a focus of current atmospheric research. At temperatures warmer than -37°C primary ice crystals are formed by heterogeneous nucleation on so-called ice nucleating particles (INP), a sub-fraction of the total ambient aerosol. The spatial distribution of lNP and their sources are highly variable. Atmospheric number concentrations of INP are often found to be very low, sometimes below one per liter. The objective of the proposed project is to measure INP number concentrations and their variability in the atmosphere. Moreover, laboratory studies are planned to improve our understanding ofthe chemical and biological properties of atmospheric aerosol particles that lead to ice activation. With the Fast Ice Nucleus CHamber, FINCH, which has been developed by our research group, we intend to measure atmospheric number concentrations of INP as a function of freezing temperature and supersaturation at several locations. The coupling of FINCH with a counterflow virtual impactor (CVI, RP2) to separate the INP from other supercooled droplets or unactivated particles was developed and tested during lNUlT-1. This coupling will be further characterized and coupled operation will be continued. After separation the INP will be analyzed by a size spectrometer or aerosol mass spectrometer (RP2), or will be sampled on filters or impactor plates for subsequent Environmental Scanning Electron Microscopy (ESEM) analysis (RP8). Field data will be complemented by comprehensive laboratory studies at the AIDA and LACIS facilities (RP6 and RP7), where, for example, the immersion freezing behavior of potentially relevant but less studied aerosol types of biological material (e.g., cellulose), porous material (e.g., zeolite), and mineral dust with relatively low amount of organic components will be studied in detail. Furthermore, regular laboratory tests/calibrations are planned with FINCH, for which standard routines will be set up. An improved characterization of the measurement uncertainties of FINCH will be derived. The measurement results will then serve as input parameters for advanced cloud models (collaboration with WP-M), to assess the role of INP for cloud formation, cloud properties and formation of precipitation.

• DFG Programme: Research Units
• Subproject of: FOR 1525: INUIT - Ice Nuclei Research Unit
• Ehemalige Antragstellerin: Dr. Diana Rose, until 8/2017