A Fully Coupled Magnetosphere-Ionosphere-Thermosphere Data Assimilation Model

Comprehensive, global and timely specifications of the Earth’s upper atmosphere (ionosphere and thermosphere) are required to ensure the effective operation, planning and management of a diverse range of systems impacted by space weather. Since 2011 the threat posed by space weather has been on the UK National Risk Register, and currently sits as the 5th most important risk to the UK (high likelihood and medium risk). One approach for mitigating such risks is the use mathematical models.

Models of the upper atmosphere have been developed over the last few decades and fall broadly into three types: statistical, physics-based or data assimilation. The data assimilation (DA) models, which fuse data with other models to provide the best possible representation of the upper atmosphere, have been shown to be the most skilful in nowcasting the atmosphere. However, these DA models have primarily been used to combine data with statistical models. The rising need for accurate and actionable forecasts has required the development of physics-based DA models.

The University of Birmingham is developing the Advanced Ensemble electron density (Ne) Assimilation System (AENeAS), a physics-based data assimilation model of the coupled ionosphere-thermosphere. One of the difficulties with such models is that measurements of the upper atmosphere are extremely sparse. Not only are the data scarce, but sometimes have not been ‘designed’ for space weather monitoring; instead they are ‘signals of opportunity’. AENeAS uses state-of-the-art mathematical techniques (the local ensemble transform Kalman filter) to assimilate data and to estimate covariances between all of the model components. This allows the model to be self-consistently updated. Also, by using an ensemble approach, AENeAS provides probabilistic nowcasts and forecasts, rather than deterministic realizations of the upper atmosphere.

AENeAS uses empirical upper and lower boundary conditions. Current research at the University of Birmingham is investigating replacing the lower boundary by coupling with the UK Met Office’s Unified Model (UM). This PhD opportunity will look to replace the empirical upper boundary of the model with a physics-based model of the magnetosphere.

It is well known that the upper boundary of ionosphere-thermosphere models is a source of large uncertainty when trying to accurately specify the conditions in the upper atmosphere. Existing research has begun to build coupled models of the system (most notably the Space Weather Modeling Framework (SWMF)). However this project will look to expand AENeAS into the magnetosphere taking advantage of the existing data assimilation system to more accurately model the magnetosphere and use the more realistic representations of the magnetosphere to better inform the ionosphere-thermosphere. Capturing the uncertainty in the magnetosphere model specification will also be incorporated into the ensemble nature of AENeAS to improve the probabilistic nowcasts and forecasts.

This fully-funded 3 year PhD opportunity will be based within the Space Environment and RF Engineering (SERENE) group at the University of Birmingham. However the position will be co-supervised by Dr. Daniel Welling, Assistant Professor of Physics at the University of Texas at Arlington, USA, an expert in magnetospheric physics and space weather modelling. As such it will be expected that the successful candidate will be able to travel and work in the USA.