Aerosols, Clouds, and Atmospheric Chemistry

MOSES is a novel flexible observing system of the Helmholtz Association specifically designed to investigate the interactions of short-term events and long-term trends. The events in focus are heat waves, hydrological extremes, ocean eddies and permafrost thaw. A first measurement campaign on heat waves took place in July 2018 near Jülich studiing soil moisture, ground - atmosphere exchange processes, and the distribution of atmospheric aerosol particles. Focus of our contribution was the determination of aerosol particle and cloud spatial distributions using a new 3D scanning aerosol LIDAR. This work will improve our understanding how aerosols, extrem weather, and climate change interact.

Aerosol particle nucleation and urban influences are studied at the Chacaltaya GAW Station (CHC) in the Bolivian Andes (16°21.014'S, 68º07.886'W, 5240 masl). The Chacaltaya mountain directly faces a plateau of 3800 masl in the south and west and is separated from the Amazon basin by higher peaks in the north and east. Research groups from La Paz, Stockholm, Helsinki, Innsbruck, Granada, Leipzig, and Karlsruhe combine their instruments to characterize the aerosol from November 2017 to June 2018. Focus of our contribution is the molecular composition of gas- and particle phase on the mountain and in the La Paz – El Alto metropolitan area.

Aerosol-cloud interaction is a first time focus of a field campaign at the SMEAR-II station in Hyytiälä, Finland. The campaign is led by the Department of Physics of the University of Helsinki, with contributions of 8 research teams from Canada, Finland, Germany, Sweden, Switzerland, and the UK. From March to May 2018, IMK-AAF is measuring aerosols and ice nucleating particles with newly developed instruments. The measurements have now successfully been started and will last until mid-May, in order to cover the transition from winter to early summer conditions and to assess the contribution of new particle formation and biosphere activity to the INP abundance in the boreal forest area.

The Measurements of Aerosols, Radiation, and Clouds over the Southern Ocean (MARCUS) field campaign is acquiring comprehensive observations of aerosols including cloud condensation nuclei and ice nucleating particles in the Southern Ocean boundary layer. The second ARM Mobile Facility is currently installed on the Australian Antarctic supply vessel Aurora Australis as it routinely travels between Hobart and the Antarctic. MARCUS has a strong link with the SOCRATES campaign targeting on clouds in the Southern Ocean and their connection to air-sea exchange processes. IMK-AAF is participating in MARCUS by monitoring the biological aerosol with the WIBS4 instrument.

A research project called the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES) is currently conducted in Tasmania, Australia. The US research aircraft NSF/NCAR HIAPER is deployed to unravel the secrets of clouds over the Southern Ocean. These clouds are frequently misinterpreted by current climate models, and in-situ investigations like SOCRATES play a vital role in enhancing modeling and forecasting capabilities in this area. The IMK-AAF is providing cloud microphysics measurements with the PHIPS probe. 

In September 2017, Dr. Nsikanabasi Umo joined IMK-AAF following his prestigious Alexander von Humboldt (AvH) Postdoctoral Research Fellowship Award. His work will focus on understanding the ice nucleation abilities of combustion and other aerosol particles at mixed-phase and cirrus cloud conditions. During October he is leading first experiments with the worldwide unique AIDA Cloud Simulation Chamber at IMK-AAF.

Nsikanabasi Umo obtained his PhD in 2014 from the University of Leeds, United Kingdom, in the field of Atmospheric Sciences. He is grateful to the AvH Foundation, Germany, for the award, which he considers a golden opportunity for his career advancement.

KIT International also welcomes Nsikanabasi Umo as new AvH Fellow.

In July and August 2017 we participated in a joint research project on the three-dimensional observation of atmospheric processes in cities (3DO) by dedicated characterisation of the urban background aerosol in the Rosenstein Park in downtown Stuttgart, Germany. This study allows the combination of very detailled meteorological observations with comprehensive characterisation of aerosol chemistry and physics.

On May 22nd, 1997, our institute celebrated the formal opening of the new aerosol and cloud chamber facility AIDA. After about two years of construction and technical runs, the first scientific campaign started on May 11th, 1997, and investigated heterogeneous chemistry on soot aerosols. Since then, a number of 5 to 10 campaigns was conducted every year, covering topics of trace gas chemistry, heterogeneous chemistry, aerosol formation, aerosol optical properties, polar stratospheric cloud formation as well as formation, growth, morphology and radiative properties of ice crystals in tropospheric clouds. The aerosol-cloud research with AIDA is also the topic of a recent KIT podcast (in German). We are grateful to all our national and international collaboration partners who contributed and still contribute to many of the AIDA campaigns.

The first experimental determination of HDO/H2O isotopic fractionation factors for ice deposition in simulated cirrus clouds for temperatures betwen 190-233 K could be achieved in the AIDA aerosol and cloud chamber (Lamb et al., PNAS 2017). In collaboration between the University of Chicago, PTB, and KIT unique measurement techniques for water isotopes were developed and applied for dedicated cirrus cloud simulation experiments. A detailed box model analysis including wall effects resulted in equilibrium fractionation factors and kinetic isotope effects with a weaker temperature dependence than extrapolations of previous work suggested. These results are fundamental for inferring processes on Earth and other planets from water isotopic measurements.

During the INUIT-CLACE campaign in January and February 2017, international teams collaborate at the Jungfraujoch Research Station (3571 m, Switzerland) to investigate aerosol-cloud processes and cloud microphysics in the mixed-phase cloud regime. KIT contributes single particle mass spectrometer measurements of aerosol particles and cloud ice residuals, as well as measurements of ice nucleating particle (INP) concentrations by taking aerosol filter samples for later offline INP analysis with an immersion freezing method.

Between December 2016 and 2020 the EU invests ~9 Mio € to further integrate 16 simulation chamber and 4 calibration facilities. This includes the AIDA aerosol and cloud chamber facility of KIT. Trans national access to these facilities is substantially supported. For details contact us or see: www.eurochamp.org.

Scientists of IMK-AAF, in cooperation with researchers of the KIT Laboratory of Electron Microscopy (LEM) and University College London (UCL) have succeeded in identifying the unique features on K-Feldspar responsible for its high ice nucleation efficiency. As reported in Science magazine (DOI: 10.1126/science.aai8034), they combined electron microscopy observations with molecular modeling to determine for the first time the atomic nature of this important inorganic ice nucleating particle. They showed that ice starts to grow on the specific crystal faces with (100) orientation that only occur at defects (steps, cracks, and crevices) on the surface of feldspar particles.