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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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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

Some environment risks


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


Spares

SPARES


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?


Using l1 warnings

Using L1 warnings


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