2-year postdoctoral position on the impact of surface turbulent exchanges and snow cover on the polar atmosphere and on teleconnections with lower latitudes

CNRM, Toulouse, France
Closing date: 29 December 2022

Applications are invited for a 24-month postdoctoral position starting in spring 2023, in the climate research group of the CNRM in Toulouse, France (http://www.umr-cnrm.fr/) to work on the impact of surface turbulent exchanges and snow cover above ice on the polar atmosphere and on teleconnections with lower latitudes.

Mission:
The mission is to provide recommendations for the parameterizations of surface turbulent fluxes in polar regions and snow schemes above sea ice to be selected for the next version of our in-house coupled climate model, CNRM-CM7, based on a series of sensitivity experiments.

The Arctic sea ice has experienced a drastic decline over the last decades, perceived as an emblematic sign of climate change. Substantial reductions in sea ice cover, and also thickness, among other modifications, have already impacted largely on local ecosystems, indigenous populations and possibly lower-latitude climate. A further reduction in the sea ice cover and thus more open water exposed to the atmosphere is expected in the near future. Two to four times faster surface warming has also been observed in the Arctic than at any other latitude over the last decades. This phenomenon is commonly referred to as the Arctic amplification. Although the available observational record is relatively short and the response of weather systems to a potential Arctic forcing is highly chaotic, both leading to major uncertainties, the Arctic climate change is thought to impact the mid-latitude atmospheric circulation to an extent and through mechanisms which are still highly debated.

Heat exchange between sea ice and atmosphere plays a crucial role on the rate of Arctic sea ice melting as well as on the teleconnections between polar and non-polar regions. Lower troposphere heating through turbulent heat fluxes (latent and sensible) dictate the thermal structure of the lower atmosphere and plays a key role in the development of atmospheric circulation anomalies. A realistic albedo feedback amplitude, central to the Arctic amplification, requires a reliable representation of surface albedo, which heavily depends on surface characteristics such as the presence of snow over sea ice.

New formulations have recently been proposed in the literature (e.g. Lupkes and Gryanik, 2015) for ice-atmosphere turbulent heat exchanges and are ready to be tested in the in-house coupled CNRM-CM climate model. Re-calibration of those formulations and machine-learning based algorithms are under development at CNRM. Work is also on-going to refine the snow cover on ice in the same climate model.

Activities :
The postdoctoral research scientist will carry out sensitivity experiments to surface turbulent exchange formulations from the most recent literature (e.g. Lupkes and Gryanik, 2015) and from innovative developments undergoing at CNRM as well as sensitivity experiments to different snow schemes currently being implemented on ice in our in-house coupled climate model CNRM-CM6. He/she will evaluate their impact on the polar and lower latitude climates. The final objective is to provide recommendations for the parameterizations and schemes to be selected for the next version of our in-house coupled climate model, CNRM-CM7.

Required qualifications:

  • Ph.D. in atmospheric dynamics, climate sciences, fluid mechanics or related
  • Knowledge about polar dynamics and polar-non polar teleconnections
  • Experience with HPC and global climate models
  • Experience with Unix and Fortran
  • Knowledge of NetCDF encoding and related data analysis tools (cdo, nco)
  • Programming skill : scripting and visualisation (e.g. bash, R, python, ncl)
  • Good command of English.
  • Collaborative spirit and communication skill

Environment:

This position is funded by the ‘Make Our Planet Great Again’ research program through the 5-year ASET project (Atmosphere Sea ice Exchanges and Teleconnections) focused on improving the representation of surface turbulent heat fluxes in polar regions and by the Horizon 2020 CRiceS project (Climate relevant interactions and feedbacks: the key role of sea ice and snow in the polar and global climate system) focusing on improving model predictions of the role of polar processes in the climate system.

The position will be held at CNRM (Centre National de Recherches Météorologiques) in Toulouse (France) in the GMGEC department (Groupe de Météorologie Grande Echelle et Climat) in the IOGA team (Interactions Océan-Glace-Atmosphère). The GMGEC department is at the forefront of climate modelling and contributes to each phase of the Coupled Model Intercomparison Project (CMIP) with its in-home coupled model, CNRM-CM, co-developed with CERFACS. The IOGA team aims at improving the representation of ocean, sea ice and atmosphere exchanges and interactions in the CNRM-CM model. IOGA contributes to the development of modelling tools used for climate predictions and projections and numerical weather predictions (for instance the SURFEX platform, used for air-ice and air-sea fluxes calculation and ocean-atmosphere coupling) and investigates coupled mechanisms and processes driving the climate system behaviour.


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