Large-scale circulation patterns associated with European climate extremes

Large-scale circulation patterns associated with European climate extremes 

Lead Supervisor: Ioana Colfescu (SEE, Leeds)

Other Supervisors: Stephen Mobbs (SEE, Leeds),Ralph Burton (SEE Leeds), Massimo Bollasina (School of GeoSciences, University of Edinburgh)

Background

Weather and climate extremes have enormous impacts on society and the environment and can result in major disasters and damage. A deeper understanding of the factors and mechanisms that influence extremes and their changes is vital and urgently needed for the development of informed policies for mitigating and adapting to climate change across a wide range of climate-sensitive activities and sectors. A large source of uncertainty is due to internal variability in the climate system (Colfescu and Schneider 2020), which in large part stems from the associated atmospheric circulation.

The risk of extreme temperatures over some regions can be linked to changes in the frequency and duration of regional circulation patterns (Horton et al. 2015). For example, the heatwave of summer 2003 was characterized by a persistent blocking anticyclone. Extremes can be accompanied by hemispheric-wide anomalous atmospheric circulation patterns, which manifest as quasi-stationary planetary waves (e.g., Teng et al. 2013). These played an important role, for example, for the 2003 European and 2010 Russian heatwaves.

Figure 1. Forest fire in Russian Siberia in 2010 (left, photo from Moscow Times) and COPERNICUS data of temperature for July 2019. Areas in red emphasize highly anomalous temperatures. Images provided by Getty and WMO.

Aim

This project will tackle the following question: To what extent large-scale planetary waves contribute to generating extremes over Europe? The analysis aims at accounting for interactions across temporal (seasonal to interannual to decadal) scales and at building a dynamical portrait of the link through the extremes cycle. 

How will you work

You will use a combined approach of observations and modelling along with machine learning techniques to understand how atmospheric circulation module

extreme events over Northern Hemisphere. You will work with scientists from NCAS as well as from the University of Edinburgh School of GeoSciences. You will have the opportunity to work in a unique team of modellers, and data analysts – which will comprise both climate and weather scientists as well as data scientists – who will guide and develop your already existent skills along with new ones. NCAS will also offer the opportunity for you to take part to outreach activities. You will have access to the UK NERC supercomputing facilities for the part of your work involving modelling and data analysis.

Methodology

A combination of observations and model (e.g., the NCAR CESM Large Ensemble, a 30-member ensemble of 1920-2080) data will be used.

Key research questions

  • What are the main large-scale planetary circulation patterns associated with extreme events over Europe ?
  • What are the key interactions temporally – seasonal to interannual to decadal – which modulate these patterns ?
  • What are the key interactions spatially (e.g links to large climate variability modes like El Nino) – which modulate these patterns ?
  • How will these patterns will change in the future in the context of climate change.

Requirements

 This project involves data analyses and plotting, hence knowledge of programming in NCL(Ncar Command Language), Python and/or Matlab is highly desirable. More sophisticated utilities for reading, analysing and plotting the data will be provided. The work will be carried out in collaboration with NCAS and University of Edinburgh scientists.

Fit with NERC research directions

The proposed research is well aligned with the NERC’s “Climate and climate change” research subject, and in particular stretches across the “Large scale atmospheric dynamics”, “Water in the atmosphere”, “Climate and climate change”, and “Regional weather and extreme events” research areas. The project will directly address challenges identified in the NERC goal to “understand and predict how the Earth System works” with regard to improving the understanding of processes in climate and how they drive its variability, especially those associated with climate change and the changing of extreme events dynamics and frequency, and their representation in models. The project is timely as it addresses relevant and compelling science problems whose uncertainties severely undermine our ability to gain a better understanding and quantification of how regional climate will evolve in the future. In particular and in line with the NERC Business of the Environment strategic plan, results from this project will tell us how environmental processes control natural resources, and water availability in particular, will help to understand processes that create natural and man-made hazards, and will inform how the processes of natural variability and man-made change work across scales. The synergy with other existing national collaborators is also an exciting opportunity.

References

Colfescu, I., Schneider, E., 2020: Decomposition Of The Atlantic Multidecadal Variability In A Historical Climate Simulation, Journal of Climate

IPCC data: http://www.ipcc-data.org/

Horton, D. E., and coauthors, 2015: Contribution of changes in atmospheric circulation patterns to extreme temperature trends. Nature, 522, 465-469.

Teng, H., and coauthors, 2013: Probability of US heat extremes affected by a subseasonal planetary wave pattern. Nature Geosci., 6, 1056-1061.