Programme Atmosphere and Climate (ATMO)

PT 3. Tropospheric trace substances and their transformation processes

In Program Topic 3, we investigate chemistry-climate interactions on a global to regional scale.
Photo: H. Vogelmann

Our research focuses on

  • atmospheric self-cleaning
  • gas-phase and aerosol processes
  • atmospheric composition change
  • chemistry-climate interactions
  • climate change and air quality

Our aim is

  • to improve the understanding of the connections between air quality and climate change and
  • to contribute data needed for assessing it.


Therefore we perform

  • experimental studies of the atmospheric self-cleaning during day and night, with particular emphasis on the link between gas-phase oxidation processes and the formation and ageing of aerosols.
  • long-term observations of the atmosphere (variability and trends).
  • model simulations of the complex chemistry and transport in the lower troposphere and its interaction with the climate system.


The improved process understanding will immediately be applied in operational systems for forecasting the global and regional atmospheric composition.



Lidar measurement of aerosols at IMK-IFU (KIT), Garmisch Partenkirchen, Germany; Photo: T. Trickl, KIT


Photo: T. Trickl

ST1. Long term observations of tropospheric composition change


We perform routine observations of trace gases and aerosol particles in the troposphere and upper troposphere-lower stratosphere (UTLS) from instrumented passenger aircraft and ground-based remote sensing. The data are used for model improvement for climate change and air quality studies. Our research also comprises instrument development.

Contributing institutes:


Zeppelin NT; Photo: A. Hofzumahaus, FZJ


Photo: A. Hofzumahaus

ST2. Radical chemistry and atmospheric oxidation processes in the lower troposphere

Atmospheric oxidation processes by reactions of radicals and ozone are of central importance for the self-cleaning of the atmosphere. Our research aims at understanding the complexity of chemistry and transport in the lower troposphere and its interaction with the Earth system. A technical challenge lies in the retrieval of observational data over the vertical extent of the variable atmospheric boundary layer at day and night. These data are needed for atmospheric model testing and development.


Contributing institute:



View above the city of Karlsruhe Photo: H. Saathoff, KIT


Photo: H. Saathoff

ST3. Gas to particle conversion, particle formation and ageing

Atmospheric oxidation (including photochemistry and nighttime radical chemistry) directly modulates aerosol properties. These are relevant for climate and air pollution. Our aim is to understand atmospheric aerosol systems in which gas-phase chemistry dominates changes in composition, morphology and environmentally relevant physical properties of the condensed phase.

Contributing institutes:



Volume mixing ratio of carbon monoxide (CO), and relative moisture (QV; superimposed, partially transparent) 19.01.2012-20.02.2012 based on analysis using the model ICON-ART. Model development, analysis and presentation of results: Global Modelling Group, IMK-ASF, KIT


Global Modelling Group, IMK-ASF, KIT


ST4. Global and regional impacts of atmospheric processes on tropospheric composition and climate

Numerical models have become indispensable tools for assessing the impacts of climate-induced changes on chemical and physical processes in the troposphere. We aim to improve the knowledge with detailed process studies in the climate relevant region of the upper troposphere by using state of the art coupled chemistry climate and chemistry transport models on different scales. The coupled chemistry climate models are also used to assess the chemistry climate interactions and the corresponding feedbacks

Contributing institutes: