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Scientific Understanding and the Risk from Extreme Space Weather Mike Hapgood

Scientific Understanding and the Risk from Extreme Space Weather Mike Hapgood M.Hapgood@rl.ac.uk / mike.hapgood@stfc.ac.uk. Some environment risks. Recent examples of extreme SpW. Halloween 2003 Recent event Well-documented Moderate on historical timescale (12 th by daily aa)

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Scientific Understanding and the Risk from Extreme Space Weather Mike Hapgood

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  1. Scientific Understanding and the Risk from Extreme Space Weather Mike Hapgood M.Hapgood@rl.ac.uk / mike.hapgood@stfc.ac.uk

  2. Some environment risks

  3. Recent examples of extreme SpW • Halloween 2003 • Recent event • Well-documented • Moderate on historical timescale (12th by daily aa) • 13 March 1989 • Big event (3rd by daily aa) • Impacts on power, drag, etc • Solar wind state not well known • 8 Feb 1986 • At solar min, but 20th largest by daily aa Data: UK Solar System Data Centre

  4. Some historical extremes • 23 Feb 1956 • SEP event with huge neutron flux at Earth’s surface => hard spectra • Gold event? • 1 Sep 1859 • Carrington event • Discovery of solar flares • Global aurorae • GIC in telegraph systems • Huge nitrate production • The perfect storm

  5. Carrington event • Carrington event is our canonical example of extreme space weather • No spacecraft • No electrical power systems – Edison was 12, Tesla only 3 • Repeat will challenge operation of spacecraft & power grids • GIC at lower latitudes where they are not usually seen • Threat to future links to solar power systems in Southern Europe and North Africa (also wind power on Atlantic margin?) • US estimates of economic impact • GIC: one to two trillion dollars (NRC workshop, May 2008) • Space: 44 billion dollars from loss of service income, 24 billion dollars in terms of spacecraft losses (ASR special issue, 2006) • Something to be scared of! • But also something that can inform us – guide our risk assessments

  6. Environmental risk & science • Assessment of risk is a standard approach to mitigate natural hazards ahead of prediction • Public authorities increasing require risk assessment for wide range of developments, e.g. • design homes to withstand 1 in 100-year risks • higher standards for design of critical infrastructure, e.g. 1 in 1000-year risks for nuclear reactors • Risk assessments critically underpinned by scientific knowledge • drives design standards • and hopefully their implementation!

  7. How is this done for other hazards?Example: 20 July 2007 floods in S. England • Flooding is a local hazard • Rainfall has local peaks • Topography channels water • Stream flows statistically independent

  8. Assessing 100-year flood risk • Collect data from similar streams, > 500 station-yrs • Normalise to stream to be assessed • Get distribution of peak flow vs return time • Apply corrections for global change

  9. How to apply to space weather? • Space weather is global • Data across Earth are correlated • So can’t combine • Can apply ideas to long STP datasets, e.g. aa • Plot opposite shows the limitations • Need other Earth-like planets? (exo-planet AKR?) • Or wait 500 years! • Statistical modelling of extremes unreliable

  10. The importance of physics! • Modelling of extreme space weather is essential • Must be physics-based or -guided • Numerical modelling unreliable outside mean ± stdev • See Tsyganenko 2005 opposite • Also Roelof & Sibeck m/p December, Dst – 20 nT, By/Bz 0 Ram 20 nPa

  11. Towards the physics of extreme events • How to make a huge auroral oval? • brings auroral effects to mid/low latitudes • expand polar cap/open field lines? • Make this big: • high V • Bz << 0 • Make this small: • time delay? • choke reconnection outflow in tail?

  12. How fast can polar cap grow? • /t ~ Vsw Bz L • Take Vsw = 2000 km s-1 • Bz = 50-100 nT • L ~ 100000 km • /t ~ 107 V • Assume Earth dipole • 108 Wb/degree • Pc grows 0.1 deg s-1 • From 70° to 45 ° in 4 mins (would envelope N Europe)

  13. What research is needed? • Response of magnetosphere to extreme inputs: • Needs modelling with comprehensive physics • What physics would be important at extremes? • What could limit the response? • Properties of extreme solar wind • Credible maximum speed? • Credible maximum Bz?

  14. Informing decision makers? • Raise awareness of credible risks from space weather • Stress global nature (no safe zone to supply help) • Explore risk magnification through impacts on interconnected systems (power, comms, …) • Risk of creeping dependency via impact on complex systems • Show the need for risk assessments • Identify the research needed to support good risk assessment

  15. SPARES

  16. What is the problem? • Extreme space weather challenges conventional institutional thinking • Rare events with huge impact. Institutions struggle with such hazards unless there is a near-continuous threat (e.g. the Cold War). • threat magnified by inter-connectedness of modern world. impacts on fundamental infrastructures cascades across economy & society • creeping dependency: everyday life is supported by complex systems whose safety under stress is not well understood. • global impact of space weather. No safe place from which help can come – unlike floods, earthquakes, ordinary volcanoes, etc. • How to proceed? • Develop natural hazard approach • Risk assessment?

  17. Using L1 warnings

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