Spatiotemporal properties of dBdt: setting limits for the highest achievable accuracy of GIC forecas

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Spatiotemporal properties of dB/dt setting
limits for the highest achievable accuracy of GIC
forecasts

• Pulkkinen A., A. Klimas, and D. Vassiliadis
• NASA Goddard Space Flight Center, USA

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Contents

• The ground effects of space weather the physical
  quantities of interest
• The event-based view to the dynamics of dB/dt
  (actually, the geoelectric field)
• The statistical view to the dynamics of dB/dt
• Summary and discussion

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The ground effects of space weather
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The ground effects of space weather
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The event-based view

• October 29-31, 2003 geomagnetic storm
• Blackout in Malmö, southern Sweden
• Details can be found from Pulkkinen, A., S.
  Lindahl, A. Viljanen, R. Pirjola, October 29-31,
  2003 geomagnetic storm geomagnetically induced
  currents and their relation to problems in the
  Swedish high-voltage power transmission system,
  AGU Space Weather, 2005.

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Equivalent currents and E, Oct 30
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The event-based view (summary)
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The statistical view

• Quantify the complexity of the spatiotemporal
  behavior
• Structure function analysis of the IMAGE
  magnetometer array data (years 2002-2003)
• White noise (no predictability)

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The statistical view
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The statistical view

• Details can be found from Pulkkinen, A., A.
  Klimas, D. Vassiliadis, V. Uritsky, and E.
  Tanskanen, Spatiotemporal scaling properties of
  the ground geomagnetic field variations,
  submitted to J. Geophys. Res., 2005.

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The statistical view (dB/dt)
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The statistical view (dB/dt)

• Conditional probability P(dIEIE)

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The statistical view (dB/dt)

• Details can be found from Pulkkinen, A., R.
  Pirjola, and A. Viljanen, Estimation of
  geomagnetically induced current levels from
  different input data, to be submitted to AGU
  Space Weather, 2005.

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The statistical view (dB/dt)
IE 150, 450, 750, 1050, 1350 nT
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The statistical view (dB/dt)

• Above scales of 80-100 s, dB/dt is essentially
  white noise both in spatial and temporal sense
  (substorms and all data)!
• It may not be possible to predict the behavior
  of dB/dt (phase and amplitude) deterministically

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The statistical view (dB/dt)

• The amplitude of dB/dt fluctuations is modulated
  by the overall geomagnetic activity (seen also in
  the Oct 2003 example)
• It may be possible to estimate the likelihood of
  large dB/dt based on the estimates of the
  background geomagnetic activity

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Summary and discussion

• The complexity of the spatiotemporal variations
  in the magnetosphere reflected also in the
  variation of auroral ionospheric currents, as
  anticipated
• Due to the stochastic nature of the phenomenon,
  deterministic forecasting of GIC may not be
  possible

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Summary and discussion

• Statistical approach for GIC forecasts likely
  needed
• Example Estimate the approximate location and
  time of intensification of large-scale
  convection-related ionospheric currents ?
  statistical estimate of GIC levels based on the
  estimate of the intensity of the currents

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Summary and discussion