NOx and HOx production by energetic electrons and impacts on polar stratospheric ozone (NOHO)

Lead Research Organisation: NERC British Antarctic Survey
Department Name: Science Programmes

Abstract

Predicting future climate change is intimately linked to understanding what is happening to the climate system in the present, and in the recent past. Studies in the Polar Regions provide vital clues in our understanding of global climate, and early indications of changes arising from the coupling of natural processes, such as variability in the amount of energy from the Sun reaching the Earth, and man-made factors. For example, the polar winter provides the extreme cold, dark conditions in the atmosphere which, combined with chemicals released from man-made chlorofluorocarbon (CFC) gases, has led to destruction of the stratospheric ozone layer 18-25 km above the ground every spring-time since the 1980's. The Southern hemisphere ozone 'hole' is now linked to observed changes in surface temperature and sea-ice across Antarctica, decreased uptake of carbon dioxide by the Southern Ocean, and perturbations to the atmospheric circulation that can affect weather patterns as far away as the Northern hemisphere.

Recovery of the ozone layer is expected now that CFC's are banned by international protocols, but this may be delayed by other greenhouse gases we are releasing into the atmosphere and natural processes including changes in the Sun's output. Although the total amount of energy as sunlight changes by a small amount (~0.1%) over the typical 11-year solar cycle, the energetic electrons and protons streaming from the Sun changes dramatically on timescales from hours to years. These particles are guided by the Earth's magnetic field and can enter the upper atmosphere, most intensely over the Polar Regions. A visible effect is the aurora, but the particles can also significantly modify the chemistry of the atmosphere down to the stratospheric ozone layer. Powerful solar storms can also damage satellites and disrupt electrical power networks. However the mechanisms by which energetic electrons generated by the Sun enter the Earth's atmosphere, and the complex, interacting processes that affect stratospheric ozone are not well understood, which limits our ability to accurately predict future ozone changes and impacts on climate.

We propose answering major unresolved questions about the impact of energetic electrons on stratospheric ozone by making observations of the middle atmosphere from Halley station in Antarctica. This location is directly under the main region where energetic electrons enter the atmosphere, making it ideal to observe the resulting effects. We will install a state-of-the-art microwave radiometer there alongside other equipment run by BAS scientists. By analysing the microwaves naturally emitted by the atmosphere high above us we can work out how much ozone there is 30-90 km above the ground as well as measuring chemicals produced in the atmosphere by energetic electrons that affect ozone. We will make observations throughout two complete Antarctic years/winters (1/2013-2/2015) and interpret them with the help of data from spacecraft that orbit the Earth and measure the energetic electrons entering the atmosphere. We will use the Antarctic observations and develop computer-based models to better understand the impact of energetic electrons on the atmosphere. The ultimate goal is to further understanding of the processes that lead to climate variability in the Polar Regions and globally - highly relevant for UK environmental science and collaborative research at an international level in which BAS and Leeds play a key role.

Planned Impact

This research will have impact in several areas:

It will have educational benefits to the wider public who will acquire a better understanding of climate change because the proposal addresses natural variability due to solar processes affecting the atmosphere against which longer term anthropogenic trends need to be detected. The effect of solar variability on climate is an issue of public interest, as indicated by its frequent appearance on the BBC News website. The subject has fuelled poorly-informed debate on anthropogenic versus natural climate change and it is important for the scientific community to produce sound observational evidence upon which arguments can be based and the relative significance of solar versus anthropogenic influence on climate can be firmly quantified.

Improved knowledge arising from this research will benefit the Met Office who will be able to use the outputs in informing and formulating representations of stratospheric ozone both synoptically and climatologically. Their decision about whether to include assimilated ozone information in Numerical Weather Prediction - weather forecasting - and climate models requires an assessment of the impact of solar energetic particle precipitation on ozone. We will communicate our results to the Met Office and the wider community, establish the specific user requirements of the Met Office, and formulate ways of incorporating our results into their assessments, through a workshop at BAS.

Other users who could benefit from this project are: Developers of advanced instrumentation, in particular UK companies developing analytical spectroscopy and imaging tools for security, forensics, pharmaceutical, and other industrial applications, and satellite instrumentation groups including the NERC-supported Centre for Earth Observation Instrumentation. The academia-industry organisations involved could benefit from the development of methodologies & protocols, computer-based data analysis tools, semi-autonomous technologies, and experience of deploying equipment in harsh environments that will arise from this project. Observational data from the Antarctic will be applicable to calibration/validation of satellite instruments monitoring the atmosphere on NASA, European Space Agency, and EUMETSAT platforms.

The wider community of scientists and engineers in government, public sector establishments, and industry will be informed of the project outcomes through the BAS website, articles in trade journals and publicity at relevant exhibitions, user group meetings, and knowledge exchange events.

Publications

10 25 50
 
Description The research has advanced understanding of the role of energetic electron precipitation (EEP) in polar middle atmosphere chemistry. EEP increases ionisation leading to increased abundance of odd hydrogen (HOx) and odd nitrogen (NOx) species. NOx and HOx catalytically remove ozone in the stratosphere and mesosphere, thereby changing heating rates, and temperature profiles. EEP thus provides a link between space weather interactions with the upper and middle atmosphere and surface climate. Observations using ground-based millimetre-wave radiometry, and satellite datasets, have been combined to investigate nitric oxide (NO) abundances following geomagnetic storms. The observed distributions indicate significant direct NO production in the Antarctic mesosphere (altitudes 50-90 km) by medium energy electrons with energies in the range ~30 keV to 300 keV. The geographic distributions of NO during wintertime, using satellite observations by the Solar Occultation for Ice Experiment (SOFIE) show that horizontal winds in the mesosphere rapidly redistribute NO away from the geomagnetic latitudes where NOx production is greatest. Comparison with model simulations including more detailed D-region chemistry show that major uncertainties remain in adequately characterising precipitating electron fluxes and the vertical transport of auroral NO from the lower thermosphere (>90 km) into the polar mesosphere.
Exploitation Route The outcomes are adding to the body of observational evidence that EEP processes needs to be adequately represented in atmospheric and climate models. In addition these processes, that affect upper atmosphere temperatures and density, need to be included in space situational awareness models to improve predictions of the orbits of the rapidly growing number of objects - space vehicles, satellites, and space debris - in low Earth orbit.
Sectors Environment

 
Description The observational data produced by this project are being shared with scientific colleagues to inform their development of atmospheric models, the aim being to accurately represent the chemical and dynamical impacts of space weather and energetic electron precipitation into the polar middle and upper atmosphere following geomagnetic storms.
First Year Of Impact 2015
Sector Environment
Impact Types Policy & public services

 
Title Atmospheric observational and model datasets: Spatial distributions of nitric oxide (NO) in the winter time, high latitude Southern hemisphere atmosphere 
Description The data are from a study investigating nitric oxide (NO) variability in the polar mesosphere and lower thermosphere during geomagnetic storms, and the role of energetic electron precipitation in NO production. The datasets include 1) processed atmospheric datasets derived from selected NO observations by the AIM-SOFIE satellite instrument, 2) estimated electron and proton fluxes derived from POES/MEPED/SEM-2 measurements, 3) zonal and meridional wind speeds calculated using the Horizontal Wind Model (HWM14), and 4) geomagnetic indices, solar wind speed, and solar proton event (SPE) data. Funding was provided by the NERC grants NE/J022187/1 and NE/R016038/1, and the New Zealand Marsden Fund. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/01306
 
Title Middle atmospheric carbon monoxide above Troll station, Antarctica from February 2008 - January 2010: Version 2.0 (2013) 
Description Data-set associated with the retrieval of carbon monoxide (CO) volume mixing ratio profiles in the middle atmosphere above Troll station, Antarctica from February 2008 - January 2010: Version 2.0 (2013). The methodology and description of the data-sets are reported in Straub, C., P. J. Espy, R. E. Hibbins, and D. A. Newnham (2013), Mesospheric CO above Troll station, Antarctica observed by a ground based microwave radiometer, Earth Syst. Sci. Data, 5, 199-208, doi:10.5194/essd-5-199-2013. The CO observations were made using a ground-based passive millimetre-wave radiometer operated by the British Antarctic Survey (BAS). The Polar Data Centre (PDC) at BAS hold the data archive and have issued a Digital Object Identifier (doi) for the data-set. 
Type Of Material Database/Collection of data 
Year Produced 2013 
Provided To Others? Yes  
Impact No significant impact as yet. 
 
Title Middle atmospheric ozone above Troll Station, Antarctica, February 2008 - January 2010: Version 1.0 (2013). 
Description Data-set associated with the retrieval of ozone (O3) volume mixing ratio profiles in the middle atmosphere above Troll station, Antarctica from February 2008 - January 2010: Version 1.0 (2013). The methodology and description of the data-sets are reported in Daae, M., C. Straub, P. J. Espy, and D. A. Newnham (2014), Atmospheric ozone above Troll station, Antarctica observed by a ground based microwave radiometer, Earth Syst. Sci. Data, 6, 105-115, doi:10.5194/essd-6-105-2014. The CO observations were made using a ground-based passive millimetre-wave radiometer operated by the British Antarctic Survey (BAS). The Polar Data Centre (PDC) at BAS hold the data archive and have issued a Digital Object Identifier (doi) for the data-set. 
Type Of Material Database/Collection of data 
Year Produced 2013 
Provided To Others? Yes  
Impact The ozone data-sets have so far been used in scientific analyses resulting in the following three journal publications: Daae, M., P. J. Espy, H. N. Nesse Tyssøy, D. A. Newnham, J. Stadsnes, and F. Søraas (2012), The effect of energetic electron precipitation on middle mesospheric night-time ozone during and after a moderate geomagnetic storm, Geophys. Res. Lett., 39, L21811, doi:10.1029/2012GL053787. Demissie, T. D., K. Hosokawa, N. Kleinknecht, P. J. Espy, R. Hibbins (2013), Planetary wave oscillations observed in ozone and PMSE data from Antarctica, J. Atmos. Solar-Terrestrial Phys. 105-106, 207-213, doi:10.1016/j.jastp.2013.10.008. Demissie, T. D., N. H. Kleinknecht, R. E. Hibbins, P. J. Espy, and C. Straub (2013), Quasi-16-day period oscillations observed in middle atmospheric ozone and temperature in Antarctica, Ann. Geophys., 31, 1279-1284, doi:10.5194/angeo-31-1279-2013. 
 
Description Collaboration with MIT Haystack Observatory 
Organisation Massachusetts Institute of Technology
Country United States 
Sector Academic/University 
PI Contribution The PI visited MIT Haystack Observatory, USA in August 2017 to discuss the NERC STO3RM project with Professor Alan Rogers, the original developer of low-cost mesospheric ozone spectrometers based on commercial satellite TV receiver technologies. He shared information on the simulation study results and details of the supplier of 13.44 GHz receivers that can potentially be used to make remote sensing measurements of hydroxyl (OH) in the middle atmosphere. The PI also gave a general talk at the Observatory.
Collaborator Contribution Professor Alan Rogers provided technical advice on the practical construction and operation of satellite-TV based ozone spectrometers. He shared the computer code used to process observational data from such instruments into atmospheric data.
Impact Procurement of 13.44 GHz receiver to investigate potential hydroxyl (OH) observations by MIT Haystack Observatory, using information provided by PI.
Start Year 2017