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“Variability and long term changes of Water Vapour in the Upper Troposphere and Lower Stratosphere derived from in-situ observations”

PhD position

Advertising institute: IEK-8 - Troposphere

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Water vapour plays a major role in the balance of planetary radiation as the most important greenhouse gas in the Earth’s atmosphere. Water vapour accounts for about 67% of the natural greenhouse effect for clear sky conditions. The knowledge about the water vapour distribution in the upper troposphere and lower stratosphere is also essential for the understanding of cloud formation processes and their impact on the Earth’s radiation budget. Among the most sensitive regions of the atmosphere for climate radiative forcing is the tropopause layer which separates the troposphere as the lowermost part of the atmosphere from the overlying stratosphere, whereby the height of the tropopause varies with season and latitude. This region is referred to as upper troposphere and lowermost stratosphere (UTLS) and describes the part of the atmosphere where the air is coldest and driest. The distribution of water vapour in the UTLS shows a large spatial and temporal variability, caused by competing transport, chemical, and mixing processes at the tropopause. These processes and in particular their long-term evolutions and trends are not yet fully understood but need to be known for trend assessments.

The target of this PhD thesis is an improved understanding of water vapour distribution and transport in the global UTLS. The PhD thesis combines for the first time the joint analysis of the two world’s largest data sets of UTLS in-situ observations of water vapour and chemical tracers (ozone, carbon monoxide) by passenger aircraft (IAGOS) and research aircraft (JULIA). Linking these observation data sets to the novel system of geophysical coordinate systems developed in the SPARC initiative OCTAV-UTLS (Observed Composition Trends And Variability in the Upper Troposphere and Lower Stratosphere ( creates a unique source of data for the investigation of the distribution of water vapour in the UTLS and associated trends which will cover two decades of data.

The proposed work addresses a highly relevant research topic and offers the potential for making substantial contributions to understanding the role of water vapour in the global climate system.

For your application please use the online recruitment system on the HITEC website Please submit your application with the relevant documentation until 7 January 2018. Only complete applications will be accepted for review.

For further details, please contact Dr. Andreas Petzold at