Project: Low frequency oceanic Rossby waves as a pacemaker for Atlantic multidecadal variability
Supervisors: David Ferreira (UoR), Dan Hodson (UoR), Bablu Sinha (NOC)
Project Description:
This project is about understanding and predicting how our climate will change from decade to decade – a topic of great societal interest since improved predictions will have beneficial impacts on areas such as human health, food security, energy efficiency, and housing and transport infrastructure.
In the North Atlantic region, decadal changes in weather and climate are linked to slowly changing ocean temperatures that vary coherently across large distances– a phenomenon known as the Atlantic Multidecadal Variability (AMV). There are different drivers of AMV involving both atmospheric and oceanic processes with naturally arising variations being modulated by anthropogenic influences.
Recent work suggests that North Atlantic temperatures are modified on decadal timescales by slowly moving basin-scale waves known as thermal Rossby waves, the existence of which depends on the north south density gradient of the ocean.
In this project we will apply and extend thermal Rossby wave theory to assess to what extent these wave processes are present and active in climate prediction models and what role they play in the model simulations of AMV. The research will be organized around three sub-themes:
- Extend current theory of thermal Rossby waves (building on Liu (1999) and Sevellec and Fedorov (2013) to account for bottom topography and the slow (anthropogenically forced) changes in stratification and current.
- Design and analyse idealised simulations (e.g. rectangular basin with idealized topography and forcing) allowing us to control and separate the various factors.
- Analysis of state-of-the art realistic climate simulations (likely from the ensemble of the CANARI project).
We expect that 1) and 2) will inform one another and develop jointly. Preliminary analysis of 3) will provide the context for developing the theoretical and idealized modelling work as well as provide an ultimate test of the advanced theory.
