|From||Eric Guilyardi <email@example.com>|
|Date||Tue, 7 Jun 2016 16:13:27 +0200|
Understanding the dynamics of extreme El Niño events
Post-doctoral offer at LOCEAN/IPSL, Paris, France
ENSO is the dominant source of interannual climate variability with large environmental impacts both in the tropics and in many regions distant from the Equatorial Pacific. Extreme El Niño events lead to about twice the surface warming of the regular events, reaching sea surface temperature anomalies of 4°C in the eastern tropical Pacific. The impact of these extremes events are larger than those of regular one, and potentially different in nature as their space and time characteristics also differ. The last well observed extreme El Niño was in 1997/98 and led to billions of US$ in damage and tens of thousands of casualties. The recent 2015/16 extreme El Niño also had major impacts, some still unfolding. Recent work has further shown that the occurrence of extreme El Niño could double under unmitigated climate change (1 out of 3 event instead of 1 out of 6 today, Cai et al. 2014). In the light of their devastating impacts and possible future increased occurrence, the understanding of the dynamics, predictability and teleconnections of these extreme El Niño events is still limited and requires a major effort from the community.
The physical processes that lead to extreme El Niños are not well understood nor modelled (Guilyardi et al. 2009a, Bellenger et al. 2014). Some studies suggested an amplifying role of the atmosphere, either via intraseasonal wind bursts (Lengaigne and Vecchi 2010, Menkes et al. 2014, Puy et al. 2016) or via heat flux feedbacks (Guilyardi et al. 2009b, Lloyd et al. 2012, Bellenger et al. 2014), but many other mechanisms can play a role (such as the influence external forcing, natural and anthropogenic). Predicting the actual amplitude of El Niño (beyond the prediction of the event itself) a few months in advance is still a challenge, as seen for the contrasting 2014 and 2015 situations.
The successful applicant will investigate the specific mechanisms and predictability of these extreme El Niño events by comparing modelling studies (to obtain statistical robustness and explore mechanisms) with the few observed cases available. In particular, an analysis of CMIP5 database that includes millennial-long simulations with and without natural and anthropogenic forcings will allow to infer if specific large-scale precursors can be found for extreme El Niño events as compared to regular one. Analysing and performing sensitivity experiments with specific climate models will allow to investigate these mechanism and predictability issues. The predictability of extreme events could for instance be investigated by performing ensemble experiments starting a few months to a year before a simulated extreme El Niño in these models. In collaboration with the rest of the IPSL team, teleconnections with higher latitudes (Arctic and Europe), mainly via the stratosphere and storm tracks, and impacts on the Indian monsoon will be quantified against that of regular El Niños using the PDF produced. The influence of external forcings (greenhouse gases, volcanoes, etc.) on these likelihood will also be assessed.
The work will involve designing and running simulations with one or several coupled GCMs (CNRM-CM5 and/or IPSL-CM6) as well as HadCM3 (via CPDN) to explore the mechanisms and sources of predictability. Extension of the experimental design to other models of the consortium will be assessed for some case studies. The position is part of the Belmont Forum GOTHAM project, with participants from UK, Germany, India, China and Japan.
Candidate should have a PhD in meteorology, oceanography, or environmental sciences, with a good background in dynamics. The position is offered for 2 years (1 year renewable) with a net monthly salary of about 2000 euros, commensurate with experience. This includes social benefits and health insurance.
For more information and application, contact Eric Guilyardi at firstname.lastname@example.org and Matthieu Lengaigne email@example.com . Applicants should send a resume, a statement of research interests, and the name, e-mail address, and telephone number of at least two references. Applications will be received until the position is filled. A start in Fall 2016 is preferred but later dates are negotiable.
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