Water Vapour and Ozone
About
Water vapour is the most important greenhouse gas in the Earth’s atmosphere and crucial in the process of cloud formatting. Among the most sensitive regions of the atmosphere for climate radiative forcing (RF) is the upper troposphere and lowermost stratosphere (UTLS), which is a transition region between the troposphere and the overlying stratosphere. In this region the air is coldest and driest, and the distribution of water vapour shows a large spatial and temporal variability. The combined time series of IAGOS and its predecessor MOZAIC cover a time span of more than 25 years and includes more than 60000 flights. Therefore IAGOS is ideal for the atmospheric research on a statistically basis.
Another important trace gas is constituted by ozone. The distribution is investigated separately from IAGOS, the working group offers the equipment for quality assurance of the sondes through the World Calibration Centre for Ozone Sondes.
Research Topics
- Water vapour budget of the upper troposphere and tropopause region
- Climatologies and transport processes
- Interaction of water vapour and cirrus clouds
- World Calibration Centre for Ozone Sondes (WCCOS)
WATER VAPOUR
For the study of the UTLS region that is of particular interest for water vapor, the dataset of the European research infrastructure IAGOS is particularly suitable due to its unique characteristics. IAGOS, together with its predecessor MOZAIC (Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft), is a global atmospheric composition observation system using autonomous instruments onboard a fleet of commercial passenger aircraft.
In addition to the processing, calibration, quality assurance and documentation of IAGOS water vapor measurement data, the tasks of the working group include the preparation of climatologies and trend analyses as well as the analysis of transport processes.
A focus is also on the investigation of the formation and persistence of contrails and their currently still largely unexplained influence on the climate, as well as the distribution of ice clouds and their long-term development using combined water vapor-cloud datasets.




OZONE
Ozone plays a unique role in the oxidative capacity of the atmosphere and acts as a potent greenhouse gas in the troposphere with a positive radiative forcing that is not offset by the radiative forcing of stratospheric ozone. The ozone distribution has a large heterogeneity, making it difficult to draw a global picture of current O3 concentrations and trends.
This was previously also complicated by the lack of ozone reference standards. Therefore, in 1996, the Environmental Simulation Facility at Forschungszentrum Jülich was established as the WMO World Calibration Center for Ozone Sondes (=WCCOS): a facility for quality assurance of ozone sondes used in GAW/GLONET, focusing on precision, accuracy and long-term stability of ozone sondes.