Geomagnetically induced currents – p physics y and applications Antti Pulkkinen UMBC/GEST @ NASA/GSFC June 25, 2010, GEM Workshop, Snowmass, CO. 1 Contents • Motivation/background i i /b k d – why h should h ld we care? • Some observational facts of interest about geomagnetically induced currents (GIC). (GIC) • Theory and modeling. • Forecasting – the Solar Shield project. project • Future challenges. • Summary Summary. June 25, 2010, GEM Workshop, Snowmass, CO. 2 Geomagnetically induced current (GIC) June 25, 2010, GEM Workshop, Snowmass, CO. 3 Why do we care? (applications) ( ) • GIC causes saturation of power transformers: • Transformer damage • Electric El i bl blackout k June 25, 2010, GEM Workshop, Snowmass, CO. 4 Why do we care? (physics) ( ) June 25, 2010, GEM Workshop, Snowmass, CO. 5 What does GIC look like? Typical amplitudes Bursts Sudden start Complex waveform June 25, 2010, GEM Workshop, Snowmass, CO. 6 57° geomag. lat. What drives (large) ( ) GIC? June 25, 2010, GEM Workshop, Snowmass, CO. Huttunen et al. (Space Weather, 2008) 7 35° geomag. lat. What drives (large) ( ) GIC? (CME-driven) Pulkkinen et al. (JASR, 2010) Coronal mass ejections the most significant driver of large GIC at midmid and high-latitudes. high latitudes June 25, 2010, GEM Workshop, Snowmass, CO. 8 57° geomag. lat. What drives (large) ( ) GIC? storm-time storm time substorms storm-time storm time pulsations Viljanen et al. (Space Weather, 2006) June 25, 2010, GEM Workshop, Snowmass, CO. 9 Theory and modeling • Modeling d li off G GIC C iis d done iin two steps: – Geophysical step – compute the geoelectric field using ggeomagnetic g induction theory. y – Engineering step – compute the GIC using the known system parameters. June 25, 2010, GEM Workshop, Snowmass, CO. 10 Geomagnetic (quasi-static) induction i lilinear, iisotropic in t i and d nondispersive di i medium Theory and modeling ∇⋅ E = ρ ε0 ∇×E =− j = σE June 25, 2010, GEM Workshop, Snowmass, CO. ∂ B ∂t (1) ∇⋅ B =0 (3) ∇ × B = μ0 j + μ0ε0 (2) ∂ E ∂t (4) (5) 11 Theory and modeling Time derivative of the horizontal magnetic field Ey = − Conductivity June 25, 2010, GEM Workshop, Snowmass, CO. 1 πμ0σ t ∫ −∞ ∞ Source field needs to be known (proportional to source currents) gx dt' t − tt' History needs to be known Conductivity structure needs to be known 12 Complex Image Method Pirjola and Viljanen (Annales Geophysicae, 1998) Pulkkinen et al. (PIER, 2009) Theory and modeling j (r ') j (r ') Ai , Ar σ (z) ez C ⋅ j (C ⋅ r ') μ0 Ai = 4π ∫ V j (r ) j(r') dV ' r − r' (1) μ0 C ⋅j ⋅j(C (C ⋅r ⋅r')) Ar = dV ' (2) ∫ 4 π V Workshop, r − r '−2 p(ω,σ (z))ez June 25, 2010, GEM Snowmass, CO. 13 Theory and modeling - GIC • General solutions for discretely and g systems y byy Lehtinen continuouslyy grounded and Pirjola, Ann. Geophys. (1985) and pp Geophys. p y (2001). Pulkkinen et al.,, JJ. Appl. • In practice, GIC can be computed from: GICi = ai E x (ri ) + bi E y (ri ) System parameters can be solved empirically or theoretically Output of the geomagnetic June 25, 2010, GEM Workshop, Snowmass, CO. induction computations 14 Forecasting – Solar Shield • In Solar Shield, we developed a two-level experimental system to forecast space weather effects on the h North N hA American i power grid; id project j funded f d d by b NASA’s Applied Sciences Program. • NASA/GSFC/CCMC and Electric Power Research Institute (EPRI) the key players. • Pulkkinen et al. ((Natural Hazards,, 2009). ) June 25, 2010, GEM Workshop, Snowmass, CO. 15 Level 1 forecasts June 25, 2010, GEM Workshop, Snowmass, CO. 16 Solar observations of eruptive events are used to compute “cone model” parameters. NASA/ESA SOHO/LASCO used. MHD outputdata at the Earth used in a statistical model Level 1 forecasts providing probabilistic estimate for GIC at individual nodes of the power grid. GIC forecast file is generated. Plasma “cone” introduced to the inner boundary of a heliospheric MHD model. Model propagates the disturbance to the Earth. Earth Computations carried out at the Community Coordinated Modeling Center. April 3, 2008 17 Level 2 forecasts June 25, 2010, GEM Workshop, Snowmass, CO. 18 Lagrange 1 observations used as boundary conditions for magnetospheric MHD. NASA’s ACE Magnetospheric MHD output used to drive geomagnetic data used. induction and GIC code providing GIC at individual nodes of the power grid. GIC forecast file is generated. Magnetospheric MHD model used to model the magnetospheric-ionospheric dynamics. Computations carried out at the Community Coordinated Modeling Center. April 3, 2008 19 Level 2 forecast example June 25, 2010, GEM Workshop, Snowmass, CO. Oct 24, 2003 20 Future challenges • Need d to account for f the h 3D 3 structure off the h Earth? h • Do we capture the substorm-related ionospheric current fluctuations in the global MHD-based MHD based modeling approach? Substorms important driver of large GIC. • Need to expand the global MHD-based modeling approach to cover lower latitudes. This is of significant US and d possibly ibl European E interest. i June 25, 2010, GEM Workshop, Snowmass, CO. 21 Summary •G GIC C global l b l phenomenon h that h a)) iimpacts llong conductor systems and b) is at the end of chain of complex physical processes. • CMEs the most significant driver of large GIC. • Modeling of GIC carried out in two steps - geophysical and engineering steps. • Emerging capability to forecast GIC based on the firstprinciples. • Many interesting challenges ahead. June 25, 2010, GEM Workshop, Snowmass, CO. 22