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Cloud Physics

Head of the department: Prof. Dr. Christiane Voigt

Despite their relevance for global climate, some physical processes on clouds and their effects on the composition of the atmosphere and its radiation budget remain unresolved. Large uncertainties in today’s assessment of climate are linked to the comprehensive characterization of clouds, their variability and their impact on the humidity and trace gas distribution of the upper troposphere and lower stratosphere (UTLS).

HALO takes off for a mission flight during ML-CIRRUS

Aviation represents the largest direct anthropogenic emitter in the UTLS region. Besides the emission of trace gases, aerosol and their precursors in that region, aviation contributes to global change via the formation of condensation trails and condensation trail cirrus clouds. In fact, contrail cirrus represents the largest contribution of the individual aviation non-CO₂ effects on present climate. The reduction and mitigation of these aviation climate effects demands a comprehensive experimental data base and targeted process studies in order to enhance our scientific understanding of the basic physical and chemical processes on clouds in the atmosphere.

We focus our research on:

• Clouds-nucleation, lifecycle, microphysics and radiation
• Impact of water vapour and clouds on the radiation budget of the atmosphere
• Ice clouds in the upper troposphere and stratosphere
• Aircraft emissions, contrails and contrail cirrus
• New technologies and alternative fuels
• Impact of trace gas transport / clouds and the composition of the UTLS
• Polar stratospheric clouds (PSCS) and ozone

We develop and implement modern methods for the direct detection of clouds, water vapour and other trace gases in the atmosphere:

• Laser spectroscopy: Cloud and aerosol spectrometers based on scattering and imaging techniques 2D-S (Spec), CAS-DPOL, FSSP (DMT) to detect the size distribution, number, cloud water content and shape of cloud particles
• Mass spectrometry: Atmospheric chemical Ionization mass spectrometer AIMS to measure H₂O, HNO₃, HCl, SO₂ and organics
• Hygrometry: frost point hygrometer, tunable diode laser TDL instruments for the measurement of H₂O from the surface to the stratosphere
• Dropsondes for the detection of humidity, temperature, wind 

The Falcon (DLR) chases NASA’s DC-8 during the ACCESS2 mission

The instruments are deployed on the research aircraft HALO and Falcon. We aim at complementing the in-situ observations with the remote sensing of clouds and with ground based and laboratory studies. Process studies help to better understand and quantify cloud formation, life cycle and climate impact.

The cloud physics group emerged from the previous Helmholtz-Hochschul Young Investigators Group AEROTROP. It is now associated with a professorship for Experimental Meteorology at the Institute of Atmospheric Physics of the the Johannes Gutenberg University Mainz.