Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

Spatiotemporal properties of dB/dt: setting limits for

the highest achievable accuracy of GIC forecasts

Pulkkinen A., A. Klimas, and D. VassiliadisNASA Goddard Space Flight Center, USA

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

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

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

The ground effects of space weather

Energy

Dynamic variationsof the electric currents

BIMFmagnetopauseBIMFmagnetopause

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The ground effects of space weather

GIC

Induction

Spatiotemporal characteristics?

E B

t

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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.

120

o

W

60oW

0

o

60

o

E

120oE 1

80

o W

50

o N

60

o N

70

o N

80

o N

25

o W

0

o

25

o

E

50

o

E

75 o E

54 o N

60 o N

66 o N

72

o

N

78 o N

Malmö

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

Oct 29, 2003

High-pass filtering

Region of the highest activity

Failures in the Swedish system

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

Equivalent currents and E, Oct 30

Oct 30, 2003

Time of the blackout (20:07 UT)

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

The event-based view (summary)

“GIC view”

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

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):

S2(r,) a(t,r) a(t ,r r)2

S() c

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

The statistical view

†

S()

Correlated signal

Break (change in the dynamics)

Disappearance of correlations (or saturation of )

S()

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

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.

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

The statistical view (dB/dt)

}

}

Substorms

after continuation to the ionosphere

S(r) c

S() cBreak in 80 - 100 s

dX/dt

dX/dt

dY/dt

dY/dt

Scaling behavior same for substorms and the entire data set

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

The statistical view (dB/dt)

• Conditional probability P(dIE|IE)

Local variant of AE

max(dBx

i

dt,dBy

i

dt)

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

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.

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

The statistical view (dB/dt)

IE = 150, 450, 750, 1050, 1350 nT

Statistics for different geomagnetic environments

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

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

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

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

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

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

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

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

Nov 17, 2005, ESWW 2005, Nov 17, 2005, ESWW 2005, Noordwijk, The NetherlandsNoordwijk, The Netherlands

Summary and discussion

Understanding GIC behavior requires “high resolution”

understanding of the solar wind-magnetosphere-ionosphere

system