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Three PhD and one PostDoc position on Arctic Amplification

The positions are funded within the Collaborative Research Center TR172 ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)3 (www.ac3-tr.de), whose second phase will start in January 2020. Within the TR172, IGMK together with the collaboration partners (Universities of Leipzig and Bremen, TROPOS and Alfred Wegener Institute) aim to better observe, understand and model processes leading to Arctic amplification.

PHD-1: Observational ice process fingerprints of arctic mixed-phase clouds

During Phase I of AC³, a W-Band cloud radar has been installed at the German/French research site in Ny-Ålesund/Svalbard and has collected a first long-term dataset of Arctic MPC. During the second phase, this radar will be complemented by a new polarimetric Ka-Band cloud radar. The successful candidate will apply an existing radar forward operator to a multi-month dataset of high-resolution simulations of MPC. These synthetic observations will be used to statistically assess model-observation biases for MPC. The candidate will also help to install and configure the new radar at Ny-Ålesund for long-term but also campaign operations. The candidate will apply polarimetric particle shape retrievals, dual-wavelength radar techniques, as well as polarimetric radar forward operators to those new datasets in order to derive additional constraints for microphysical process simulations. These new observations will be the basis to better understand the observed statistical biases and to achieve consistency between improved high-resolution ICON simulation performed in the partner PhD project (PHD-2) and the observed microphysical process signatures.

 

Specific requirements for this project:

  • experience in cloud remote sensing (preferentially radar)
  • strong interest in setting up and analyzing data from cloud radars and other remote sensors
  • strong interest in ice cloud microphysics, mixed-phase clouds, and evaluation of model simulations with observations

According to the guidelines in the official job posting, please send your application and questions regarding this project to Dr. S. Kneifel (skneifel@meteo.uni-koeln.de).

     

PHD-2: Assessment of mixed-phase clouds by high-resolution modelling

During Phase 1 of AC³, the new ICON Large-Eddy-Model has been tested for high-resolution simulations around Ny-Ålesund/Svalbard under arctic conditions. During the second phase, the model and its setup will be consolidated and explored. The successful candidate will for the first time perform long-term simulations around Ny-Ålesund in order to create a statistical basis for the comparison with the advanced measurements taken in the partner PhD project (PHD-1). Besides the long-term simulations, also several sensitivity studies will be performed to investigate the influence of the setup and the forcing conditions like the representation of the surface. Based on the different sets of simulations and the unique combination with the measurements new insights in the representation of the microphysical properties of arctic mixed phase clouds in the applied parameterizations can be derived. Within this project, these new ideas will be implemented and tested in the ICON-LEM framework with the aim to improve the parameterizations and advice the coarser climate and weather prediction models.

 

Specific requirements for this project:

  • strong interest in atmospheric sciences as well as an interest in mathematical modelling of the atmosphere

  • strong interest in modelling and understanding of ice cloud microphysics and mixed-phase clouds

According to the guidelines in the official job posting, please send your application and questions regarding this project to Dr. V. Schemann (schemann@meteo.uni-koeln.de).

     

PHD-3: Understanding controls on Arctic mixed layer evolution using Large-Eddy Simulations based on MOSAiC data

As part of the ongoing MOSAiC field campaign in the high Arctic (http://mosaic-expedition.org) the Polarstern Research Vessel is currently making unprecedented measurements of low level turbulence, clouds and radiation in the Arctic Mixed Layer (AML) during winter. In this PhD project, high-resolution Large-Eddy Simulations (LES) will be generated to accompany these observational datasets. The objective is i) to supplement the measurements with virtual three-dimensional fields, and ii) to use the LES as a laboratory to study interactions between turbulence, clouds, radiation, the surface and larger–scale dynamics. The simulations will be performed for each suitable day during the MOSAiC drift, yielding a library of over a 100 cases. The Lagrangian setup of these simulations follows air masses as they move towards the ship. Model results will be evaluated against independent MOSAiC measurements. Statistical interpretation of big datasets will be performed to identify controls on the evolution of the AML as embedded in warm and moist air intrusions. Hypotheses will be tested concerning the formation and maintenance of humidity layers above the thermal inversion of the AML, focusing on the role of surface heterogeneity. Obtained results will be published in high-end peer-reviewed scientific journals and presented at international conferences.

Specific requirements for this project:

  • A strong interest in high-resolution numerical simulation of geophysical flows, boundary-layer meteorology, Arctic clouds and climate, and conceptual modeling

  • Interest in confronting simulations with state-of-the-art MOSAiC measurements, in close collaboration with our project partners at TROPOS in Leipzig

  • An investigative mindset, highly motivated to gain new scientific insights into an ongoing major shift in Earth's climate (Arctic Amplification)

According to the guidelines in the official job posting (Stellenausschreibung), please send your application and questions regarding this project to Prof. Dr. R. Neggers (neggers@meteo.uni-koeln.de)

PostDoc-1: Variability of arctic clouds from ground-based sensor synergy

During Phase I of AC³, a W-Band cloud radar has been installed at the German/French research site in Ny-Ålesund/Svalbard and has collected a first long-term dataset of Arctic clouds. The successful candidate will continue the time series of cloud observations at Ny-Ålesund and analyze the long-term statistics of clouds at this site. To asses the spatial variability of liquid water path and integrated water vapor on a local scale, scanning microwave radiometer (MWR) measurements will be investigated. The cloud observations at Ny-Ålesund will also be set into context to measurements of the MOSAiC (Multidisciplinary Observatory for the Study of Arctic Climate), COMBLE (Cold-Air Outbreaks in the Marine Boundary Layer Experiment) and aircraft activities within TR172. To this end, the successful candidate will develop and apply consistent MWR retrieval algorithms for the different instruments at the different locations. He/she will also compare the cloud observations at Ny-Ålesund to long-term observations at other Arctic sites, e.g. Barrow (Alaska) and Summit (Greenland). Satellite-based cloud measurements will be exploited to set the site-specific information in a broader context.

 

Specific requirements for this project:

  • strong experience in cloud remote sensing (preferentially microwave radiometer and radar)
  • strong interest in operating and analysing remote sensing instruments
  • strong interest in cloud microphysics

According to the guidelines in the official job posting, please send your application and questions regarding this project to Dr. K. Ebell (kebell@meteo.uni-koeln.de).