Quantifying Energetic Particle Precipitation into the Atmosphere (QEPPA)

Lead Research Organisation: Lancaster University
Department Name: Physics

Abstract

This proposal will combine the expertise and data sets provided by Lancaster University and the British Antarctic Survey to answer a series of important questions regarding the significance of charged particle precipitation into the atmosphere on atmospheric chemistry. This will advance the debate on how solar activity affects tropospheric and stratospheric variability by establishing a key link in the chain. Two inter-hemispheric, ground-based networks of instruments will be used to provide estimates of energetic electron precipitation. Lancaster is the PI institute for the Global Riometer Array (GLORIA) and BAS is the co-PI institute of the Antarctic-Arctic Radiation-belt Dynamic Deposition VLF Atmospheric Research Konsortia (AARDDVARK). This project aims to provide a global picture of the fluxes of energetic electrons entering the atmosphere in order to answer the key question: what is the significance of energetic electron precipitation to atmospheric chemistry and dynamics?
The primary aim of this proposal will be to utilise the riometer (relative ionospheric opacity meter) and VLF (very low frequency) radio wave observations together with advanced modelling of the electron distributions in the magnetosphere, in order to determine the characteristics of energetic electron precipitation in the atmosphere and the polar regions in particular. These instruments respond to different electron energies and by combining the observations with suitable modelling of the electrons in the magnetosphere it is possible to make estimates of the location, energy spectrum and flux of electron precipitation events, particularly in the polar regions, and at energies that have implications for atmospheric chemistry in the stratosphere and mesosphere.
The data product will be of particular use for coupled-climate models as an input to represent the coupling between geomagnetic activity and the atmosphere, instead of broad geomagnetic indexes such as Ap or Kp. Although the key aim is to produce electron flux spectra, this can be easily converted into ion-pair production rates or even NOx profiles to suit the model input requirements. This data product will be employed in an ion and neutral chemistry model to determine the corresponding level of NOx production. We will use this to answer the following key questions:
1. How does the NOx profile vary during substorms and storms?
2. How does NOx production vary between hemispheres?

We will determine the role of solar wind driving of atmospheric chemistry rather than solar irradiance. The inter-hemispheric nature of GLORIA and AARDDVARK means that we will be able to determine NOx production in both polar regions simultaneously and determine differences and similarities from season to season. These are important questions concerning the importance of atmospheric chemistry in the upper atmosphere and how it is influenced by geomagnetic activity. We will therefore be able to answer what is the significance of energetic electron precipitation to atmospheric chemistry and dynamics?

Planned Impact

Beneficiaries of this research:
Scientists involved in atmosphere and climate modelling
Scientists involved in space physics, notably the radiation belts and ionospheric electrodynamics
Policy makers (national and international) with responsibility for consideration of the impact of man's activity on the polar climate.
Airlines and other HF radio users in the Polar Regions.
The general public, particularly for inspiring children to adopt a scientific career with emphasis on the real-world system.

How they will benefit from this research:
The Academic Beneficiaries section detailed how the academic community would benefit from our work, but to summarise: The results of this research will improve our understanding of how solar activity can influence the polar climate, particularly in terms of variability. Increasing the understanding of one of the climate's driving factors in the Polar Regions will improve climate modelling performance and improve short-term (seasonal) climate predictions, particularly for North West Europe and the UK. The regular identification of electron precipitation morphology will provide information on the satellite radiation environment as well as context for observations of large scale system studies of magnetosphere-ionosphere coupling.
The results of this study will feed into coupled climate models and as such will determine the role played by one poorly understood, yet potentially powerful, mechanism linking solar variability to the polar climate. This is recognised as an area of required further research by the IPCC. Consequently it has particular importance for policy makers with an interest in mitigation of climate change effects. This is especially true for the UK where changes to temperatures in the polar regions can have a direct impact on severe weather in the UK.
Energetic electron precipitation increases ionization at mesospheric altitudes resulting in the attenuation of high frequency (HF) radio waves. This is a significant natural hazard for airlines and other HF radio users in the polar cap regions (such as the military). Large precipitation events result in the diversion of aeroplanes from desired flight paths, causing disruption to timetables and increasing fuel consumption. Understanding of the patterns of precipitation and the particular drivers that cause them will lead to better prediction; foreknowledge of the location and timing of such events will mitigate the economic impact and disruption to travel making this a potentially valuable resource for industries (such as airlines and defence) that rely on HF communications across the polar cap and auroral zones. An improved precipitation prediction model could be online by the end of the grant period and so available to the user community on the same timescale.

What will be done to ensure that they benefit from this research?
Results of the project will be disseminated in the appropriate literature and at international conferences. A dedicated workshop will be held to unite members of the atmosphere/climate community with the space physics community. This workshop will be a prime opportunity to communicate the relevant results of the work to the key beneficiaries. A dedicated website will be set up to provide direct access to the data and code that underpins the Level 2 data product as well as the data product itself. Targeted presentations will be made at USA and European workshops on space weather effects on technological systems. School activity days will be held to promote the science to school children. These will consist of interactive talks and hands on manipulation of data. Pupils will get a chance to quiz active scientists, see an RF laboratory with a hands-on display of the equipment used to generate the data used in the proposal. We will target 2 different age groups (11-14) to interest them in natural sciences and (14-16) years old to try linking the project science into their GCSE curriculum.

Publications

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Beharrell M (2015) Substorm-induced energetic electron precipitation: Morphology and prediction in Journal of Geophysical Research: Space Physics

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McKay D (2015) All-sky interferometric riometry in Radio Science