Periodic Reporting for period 1 - CLOUD-MOTION (CLOUD-MObility, Training and InnOvation Network)
Berichtszeitraum: 2017-09-01 bis 2019-08-31
New-particle formation, or nucleation, largely determines the number concentration of ultrafine particles (<100 nm) in the atmosphere, and models predict that approximately half of global cloud condensation nuclei (CCN) form in this way. Nucleation is therefore critical to aerosol-cloud interactions and climate. Due to the non-linear nature of the processes, competing mechanisms, and the complex variety of chemical compounds that influence nucleation and early particle growth, we are still far from a satisfactory level of understanding. Ice nucleation also plays an important role governing the radiative properties of ice and mixed-phase clouds and influencing precipitation and climate, but only a tiny, poorly understood fraction of atmospheric particles act as heterogeneous ice-nucleating particles (INP).
Both of these topics - aerosol nucleation and ice nucleation - can be studied under atmospheric conditions with great precision at the CLOUD aerosol and cloud chamber facility at CERN . The experimental data are parametrized to improve the representation of aerosols and clouds in regional and global models. CLOUD research is systematically updating models with microphysical and chemical processes based on experimental data thereby improving air-quality models and climate-change predictions, two topics of highest relevance and timeliness for society.
CLOUD-MOTION represents a network of early stage researchers (ESRs, all PhD students) at 10 institutions across Europe. The major research activity of the network is three sets of joint experiments carried out at the CLOUD aerosol chamber at CERN to which all ESRs contribute. The focus of investigations is on:
a) aerosol nucleation and growth in pristine environments (tropical free troposphere and unpolluted marine environments),
b) aerosol nucleation and growth in the anthropogenically polluted atmosphere (urban environments),
c) the formation of ice on glassy Secondary Organic Aerosol acting as Ice Nucleating Particles (“glassy SOA as INP”).
The objectives of CLOUD-MOTION reflect recent major advances in knowledge and instrumentation. Highly complex systems which include up to hundreds of components participating in nucleation and growth can now be handled. CLOUD is the world’s first experiment to reach the technical standards required to measure nucleation and growth of aerosol particles under controlled atmospheric conditions in the laboratory. A beamline at CERN allows to simulate the role of galactic cosmic rays for aerosol formation and cloud processes.
As the core of the research activities two experiments (CLOUD13T and CLOUD13) were conducted at the CLOUD chamber to investigate aerosol nucleation processes. Comprehensive measurements of the precursor chemistry as well as the nucleation and initial growth rates were conducted for a number of chemical systems, comprising several hundred experimental runs. The focus of investigations was on the following systems:
• tropical free troposphere: isoprene and α-pinene in combination with sulphur compounds for a range of temperatures;
• marine system: iodine and sulphur compounds that representative for the atmosphere in coastal or open ocean areas;
• urban nucleation: aromatic compounds such as toluene and cresol as well as the inorganic acid-base system of sulphuric and nitric acid with ammonia and dimethylamine.
Focus of the CLOUD13T experiment was the characterization of ion processes in the chamber.
In both CLOUD experiments data sets of excellent quality were obtained. Detailed interpretation has started.
All ESRs received comprehensive training on the preparation, operation, troubleshooting, and data analysis procedures for their individual instruments or models. They all learned also to operate the complex CLOUD chamber for conducting the shifts during the experiments.
Progress of the ESRs was regularly reviewed. Overall, excellent progress has been achieved by all ESRs.
For the ESRs the first phase was dominated by the acquisition of know-how and scientific background, operational trainings, instrument characterization and conducting the experiments. Very good progress was achieved, and some data analyses already matured into paper manuscripts. The third experiment of CLOUD-MOTION (CLOUD14, Sep-Nov 2019) focusses on Ice nucleation on glassy secondary organic aerosol. After this experiment, the ESRs will shift their focus to the data analysis and dissemination. As an exploitable result, an innovative gas chromatographic (GC) coupling design for a TOF mass spectrometer was developed, characterized and tested by the ESR at Tofwerk AG. This will be patented and commercially exploited.
Six collaboration meetings and data workshops took place, two CLOUD-MOTION Summer Schools were held.
These systems include, e.g.:nucleation and growth of particles from isoprene and α-pinene oxidation with and without sulfuric acid at temperatures down to -50°C;
iodic acid, sulfuric acid, and methyl sulfonic acid (marine system); oxidation of toluene and cresol, as well as the inorganic acid-base system of sulphuric and nitric acid with ammonia (urban system).
As a special highlight we observed exceptional growth properties for the HNO3-NH3 system. A manuscript on these measurements is under review in Nature (Wang et al., in review, 2019)
A patent application is currently in the final stages of preparation describing a novel GC-TOF coupling developed by the ESR from TOFWERK.
Analysis and integral interpretation of the data from the CLOUD13 and CLOUD13T experiments will be performed in the upcoming phase of the project. An exact quantification of aerosol nucleation under a large range of atmospheric conditions can be expected. Similarly, significant process understanding is expected from the liquid and ice cloud experiments. We are confident that all scientific objectives as documented in Annex I of the Grant Agreement will be met by the end of the project.
Results will be published in scientific journals and presented at international conferences. The data will be the basis for parametrizations that will enter atmospheric models up to the global scale. The impact of nucleation and growth on CCN, clouds, climate and air quality will be assessed.
The impact of CLOUD-MOTION is manifold: Atmospheric research in Europe will benefit from a well trained new generation of young scientists equipped with cutting edge knowledge and research skills.
The new knowledge generated within the project will impact our understanding of various atmospheric processes in many regions of the atmosphere. Such improved knowledge about the complex processes of atmospheric and climate change is mandatory to determine, e.g. remaining carbon budgets, and to guide the grand transformation of society towards a carbon-neutral and sustainable society.