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Scientific Understanding and the Risk from Extreme Space Weather Mike Hapgood

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Scientific Understanding and the Risk from Extreme Space Weather Mike Hapgood [email protected] / [email protected] 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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recent examples of extreme spw
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

some historical extremes
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
carrington event
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
environmental risk science
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!
how is this done for other hazards example 20 july 2007 floods in s england
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
assessing 100 year flood risk
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
how to apply to space weather
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
the importance of physics
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

towards the physics of extreme events
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?
how fast can polar cap grow
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)
what research is needed
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?
informing decision makers
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
what is the problem
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?