The projection of climate warming largely depends on the emission scenarios, but also on the feedback of terrestrial ecosystems. To this end, understanding photosynthetic carbon uptake, or gross primary production (GPP) is paramount to analyze the responses of terrestrial ecosystems to climate change; however, this is challenging due to the fact that GPP cannot be directly measured on a scale larger than the leaf level. Carbonyl sulfide (COS or OCS), which may be a useful tracer for GPP estimates, provides a way to partition the net ecosystem exchange between the biosphere and the atmosphere into GPP and respiration. In the stratosphere, breakdown on COS leads to aerosol particles that contribute to climate cooling. Until now, significant uncertainties exist in the sources and sinks of COS, which limits the application of COS as a tracer for GPP.

This PhD project aims to improve our understanding of the global COS budget by using AirCore to measure COS profiles in the under-sampled stratosphere. AirCore is an innovative sampling tool that collects air samples during descent from a high altitude for vertical profile measurements. Within the project, the candidate will perform COS observations at multiple scales. This position is part of the COS-OCS project that is conducted with the universities of Wageningen and Utrecht. Specifically, the successful candidate will perform the following tasks:

1. development of the AirCore technique to obtain accurate measurements of COS using a quantum cascade laser based spectrometer
2. perform field campaigns to obtain COS vertical gradients and stratospheric COS mole fractions at high latitudes, mid-latitudes, and in the tropics
3. calibration of the COS measurements from remote sensing techniques, e.g. ground-based Fourier Transform Spectrometers and satellites
4. contribute to field measurements and modelling studies, with the aim to reduce uncertainties in the COS budget.

The successful candidate should have:
• a master degree in atmospheric science, meteorology, chemical engineering, (applied) physics or a related discipline
• excellent communication skills in oral and written English
• good practice in team working, and affinity with working in the field.

Fixed-term contract: 48 months.

The University of Groningen offers, in accordance with the Collective Labour Agreement for Dutch Universities, a salary of € 2,222 gross per month in the first year, up to a maximum of € 2,840 gross per month in the fourth and final year, based on a full-time position (1.0 FTE), excluding a holiday allowance of 8% and a 8.3% end-of-the-year allowance. The position is limited to a period of 4 years. A PhD training programme is part of the agreement and the successful candidate will be enrolled in the Graduate School of Science and Engineering.
The successful candidate will first be offered a temporary position of one year with the option of renewal for another three years. Prolongation of the contract is contingent on sufficient progress in the first year to indicate that a successful completion of the PhD thesis within the next three years is to be expected.

Application
The applications can be submitted until 28 February 2018 23:59 h / before 1 March 2018 Dutch local time by means of the application form (click on "Apply" below on the advertisement on the university website).

Application should include:
• letter of motivation
• CV (including contact information for at least two academic references)
• transcripts from your bachelor’s and master’s degree.

Applications received before 1 February 2018 will be given full consideration; however, the position will remain open until it is filled. Exceptional candidates for a postdoc position will also be considered.

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Faculty of Science and Engineering

Founded in 1614, the University of Groningen enjoys an international reputation as a dynamic and innovative institution of higher education offering high-quality teaching and research. Flexible study programmes and academic career opportunities in a wide variety of disciplines encourage the 30,000 students and researchers alike to develop their own individual talents. As one of the best research universities in Europe, the University of Groningen has joined forces with other top universities and networks worldwide to become a truly global centre of knowledge.

Within the Faculty of Science and Engineering, a 4-years PhD position is available at the Center for Isotope Research of the University of Groningen in The Netherlands, with the topic of Improving gross carbon flux estimates with AirCore carbonyl sulfide measurements.