Overview

The interaction between the Sun’s and the Earth’s plasma environments is very dynamic and one of societal and commercial importance. A large proportion of the energy from this terawatt system is transferred from the outer magnetosphere inwards by MHD waves, which propagate along magnetic field lines and into the upper atmosphere (ionosphere), where the energy is dissipated (Fig. 1).

By undertaking this study, the student will be able to gauge the impact of geomagnetic activity on the Earth’s environment. “Space Weather” hazards are now part of the Government’s National Risk Register since geomagnetic storms are known to affect human activities on the ground and in space. Recently, it has also become apparent that nonlinear effects in the upper atmosphere may also influence tropospheric climate, including energetic particle precipitation (EPP, associated with MHD waves) effects on stratospheric ozone (e.g. Seppälä et al., 2009) and changes to the geoelectric circuit. This project will, therefore, align well with CENTA’s theme of Anthropogenic Impacts and Environmental Sustainability.

The Radio and Space Plasma Physics (RSPP) group at the University of Leicester have unique UK access to a number of important data sets including ground magnetometers (through SuperMag), ionospheric radars (including EISCAT and SuperDARN) and satellites (e.g. the Van Allen Probes, VAPs). This project will exploit these facilities to explore energy deposition in the upper atmosphere via MHD waves. 

MHD waves can be broadly categorised as being externally (solar wind) driven or excited through wave –particle interactions between the Earth’s magnetic field and drifting plasma in the van Allen belts. Externally-excited (large scale) waves are most readily detected by ground magnetometers (SuperMag) whereas particle-driven (smaller scale) waves are more easily observed within the ionosphere and magnetosphere. The electric field of MHD waves drive the ionosphere into motion, which is directly measureable by radars such as EISCAT and SuperDARN. The NASA VAPs will also observe waves in the magnetosphere and the NASA Wind spacecraft monitors the solar wind driver for context. The data collected will provide input to up-to-date models of MHD wave generation and solar forcing of the lower atmosphere.

An illustration of the coupled Solar wind-magnetosphere-ionosphere system highlighting the key regions of geospace in this project. (Jerry Goldstein, Southwest Research Institute, USA).

Methodology

Initially, utilising a newly developed analysis method (based on the Lomb-Scargle periodogram) the student will detect MHD waves in an extended (11+ year) data set provided by SuperMag. The observations will be exploited in conjunction with contemporaneous measurements from the EISCAT and SuperDARN radars to provide a detailed picture of the ionospheric conductivity, electrodynamics and EPP occurring during events identified.

In addition, examination of upstream solar wind (Wind) and geomagnetic conditions along with measurements within the magnetosphere (VAP) will provide a way of determining how the waves are generated. A database of events and their characteristics over a period of years will be derived. These will be compared with existing models of MHD waves and EPP effects on lower atmospheric climate.

Training and Skills

The project will build upon over 40 years of experience within the Radio and Space Plasma Physics (RSPP) group in the exploitation and analysis of geophysical data and combining ground- and space-based observations of Space Weather phenomena. Training in relevant plasma and atmospheric physics and radar techniques will be provided as well as training in computer programming, model simulations and the data analysis required.  The student will gain a great deal of expertise in research methods, data management, analytical thinking and computer programming.

CENTA students are required to complete 45 days training throughout their PhD including a 10-day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to the student's projects and themes. 

Timeline

Year 1: The student will become familiar with the various instruments and data types required to undertake the study. They will gain skills in programming and analysis techniques. Furthermore, the student will undertake a detailed study of the SuperMag data set and create a database classifying the different types of events observed.

Year 2: The student will extend their studies to include case studies incorporating ionospheric (radar), magnetospheric (VAP) and solar wind (Wind) measurements to provide a more comprehensive view. A database of wave and driver characteristics will be developed.

Year 3: The robustness of the database will be tested by detailed examination of case events using all available data. These will be compared with recent models of magnetospheric wave generation, lower atmospheric forcing and climate.

Throughout the project, the student will be expected to publish their work in refereed journals and present their findings at national and international meetings.

Partners and collaboration (including CASE)

The work will be undertaken in collaboration with Dr Jesper Gjerloev, PI of SuperMAG at the Johns Hopkins University, USA. New collaborations have been established with Dr J Rae at UCL and Dr C Watt at the University of Reading, both experts in MHD waves, Dr I Cnossen at NERC’s British Antarctic Survey, an expert in solar forcing of the lower atmosphere and Prof David Jackson at the UK Met Office. As the PI institute of SuperDARN, Leicester also has access to all SuperDARN data and strong links with the PI institutes of the >30 constituent radars around the world.

Further Details

Dr Darren Wright

Radio and Space Plasma Physics Group

Department of Physics and Astronomy

University of Leicester

Tel: +44 116 2523568

Email: Darren.Wright@le.ac.uk