Hamrin, M., Norqvist, P., Marghitu, O., et al. Department of Physics, Umeå University, Sweden Nordic Cluster Meeting, Uppsala, August 2011 Hamrin, Nordic Cluster Meeting, 2011

Our previously published papers on plasma sheet (PS) energy conversion. Our previously published papers on plasma sheet (PS) energy conversion. Recently we have obtained experimental evidence of the relation between PS energy conversion and Recently we have obtained experimental evidence of the relation between PS energy conversion and 1.the energy input at the magnetopause 2.the energy flow towards the ionosphere Work in progress… Work in progress… Now I’m looking for advice from you! Now I’m looking for advice from you! Splinter? Splinter? Hamrin, Nordic Cluster Meeting, 2011

~20 years ago, the view on PS transport processes changed by the discovery of BBFs [Baumjohann et al., JGR, 1990; Angelopoulos et al., JGR, 1992]. PS plays a fundamental role for the energy conversion and transport processes in the Earth’s magnetosphere (Msp). PS plays a fundamental role for the energy conversion and transport processes in the Earth’s magnetosphere (Msp). Primary energy source: Solar wind kinetic energy, transferred into the Msp by means of reconnection. Primary energy source: Solar wind kinetic energy, transferred into the Msp by means of reconnection [Paschmann et al., Nature, 1979]. Tail reconnection releases energy stored in the tail magnetic field.  Magnetic energy converted to kinetic energy (BBFs). Tail reconnection releases energy stored in the tail magnetic field.  Magnetic energy converted to kinetic energy (BBFs). Energy is transported away as Poynting flux and particle flux. Possibly recurring conversions in the PS between electromagnetic energy and kinetic energy (plasma bulk and thermal) forms. Energy is transported away as Poynting flux and particle flux. Possibly recurring conversions in the PS between electromagnetic energy and kinetic energy (plasma bulk and thermal) forms [Hamrin et al., JGR, 2011]. Some energy dissipated in the auroral ionosphere. Some energy dissipated in the auroral ionosphere [Hamrin et al., Ann Geophys, 2006, Hamrin et al., Ann Geo, JGR, 2011]. Appealing to explore the structure of the PS energy conversion and transport in relation to the SW energy input and auroral dissipation! Appealing to explore the structure of the PS energy conversion and transport in relation to the SW energy input and auroral dissipation! Hamrin, Nordic Cluster Meeting, 2011

Poynting’s theorem: Poynting’s theorem: Energy of bulk motion: Energy of bulk motion: Plasma acc./decel. by Lorenz force, JB Plasma acc./decel. by Lorenz force, JB Study E∙J in the PS with Cluster! (JB)  v= (-vB)  J=E  J Study E∙J in the PS with Cluster! (JB)  v= (-vB)  J=E  J E∙J<0 (generator) E∙J>0 (load) Mechanical energy Electromag. energy Power density Hamrin, Nordic Cluster Meeting, 2011

J=B from FGM J=B from FGM =E sc /n from CIS -vB =E sc /n from CIS -vB Reference frame of irreversible energy dissipation: neutral wind system ≈ GSE (GSM) Reference frame of irreversible energy dissipation: neutral wind system ≈ GSE (GSM) We study clearly identifiable regions of energy conversion: We study clearly identifiable regions of energy conversion: “ECR”= Energy Conversion Region: “CLR” = Concentrated Load Region “CGR” = Concentrated Generator Region “ECR”= Energy Conversion Region: “CLR” = Concentrated Load Region “CGR” = Concentrated Generator Region ‘Automatic’ ECR database: 2001, 2002, 2004, 15-20R E. ‘Automatic’ ECR database: 2001, 2002, 2004, 15-20R E. 428/127 CLRs/CGRs from 220 Cluster PS passages (2730h) 428/127 CLRs/CGRs from 220 Cluster PS passages (2730h) E∙J ∑E∙J Hamrin, Nordic Cluster Meeting, 2011

1. Concentrated regions (time, space) of energy conversion  Consistent with high level of fine structure in PS 2. CLRs are stronger and more frequent than CGRs  Consistent with PS on the average behaving as a load 3. CLRs/CGRs preferring locations towards CPS/PSBL (high/low )  Consistent with MHD simulation  Consistent with MHD simulation [Birn and Hesse, Ann Geo, 2005] 4. ECR life time and (cross-tail) scale size = 1-10 min and a few R E  Consistent with BBF scale size HD simulation and BBF duration  Consistent with BBF scale size [Nakamura et al., Adv Space Res, 2005; Walsh et al., Ann Geo, 2009], MHD simulation [Birn and Hesse, Ann Geo, 2005] and BBF duration [Juusola et al., JGR, 2009] 5. Energy conversion increases with the geomagnetic activity (AE, Kp) 6. Correlated with auroral activity (AE and event investigations) Consistent picture of the PS energy conversion! Consistent picture of the PS energy conversion! Hamrin, Nordic Cluster Meeting, 2011

Now heading towards the new results linking the PS energy conversion to… 1. …SW input into the Msp 2. …transport of energy to the ionosphere (BBFs, Poynting flux) Hamrin, Nordic Cluster Meeting, 2011

Dayside reconnection (SW energy input) is favorable towards southward IMF Bz Dayside reconnection (SW energy input) is favorable towards southward IMF Bz ECRs are more common after periods of stable southward IMF ECRs are more common after periods of stable southward IMF Expected but now we have verification! Expected but now we have verification! More significant result for CLRs. Perhaps because of differences between the spatial distributions of CLRs and CGRs with respect to the Cluster orbit (?) More significant result for CLRs. Perhaps because of differences between the spatial distributions of CLRs and CGRs with respect to the Cluster orbit (?) Hamrin, Nordic Cluster Meeting, 2011 #ECRs Bz(T-20min)<0 Bz(T-20min)>0 Bz(T-20min)<0

Some extra material… Some extra material… Number of ECRs observed t hours after stable 1h- intervals of southward or northward IMF. Number of ECRs observed t hours after stable 1h- intervals of southward or northward IMF. The memory of the IMF direction remains up to ~5h. The memory of the IMF direction remains up to ~5h. Why? Why? Hamrin, Nordic Cluster Meeting, 2011 ’Stable level’ of fluctuations

ECRs are associated with high speed flows (cf. background data – gray) ECRs are associated with high speed flows (cf. background data – gray) ECRs are more common during GSM Vx>0 than Vx 0 than Vx<0 (not shown) Vx generally gives the most dominant contribution to Vtot, but there are many ECRs where the Vyz contribution cannot be neglected (not shown) Vx generally gives the most dominant contribution to Vtot, but there are many ECRs where the Vyz contribution cannot be neglected (not shown) Manuscript in preparation, Marghitu et al. Manuscript in preparation, Marghitu et al. Hamrin, Nordic Cluster Meeting, 2011 Vtot [km/s] Norm # ECRs |Vtot| [km/s]

Main conclusion 1: There is a strong correlation between high speed flows and ECRs. Main conclusion 1: There is a strong correlation between high speed flows and ECRs. (Future research: Linking generators to the breaking of the plasma) Hamrin, Nordic Cluster Meeting, 2011

Sx within ECRs and RAND intervals (background reference data) Sx within ECRs and RAND intervals (background reference data) Observation 1. Background data  Poynting flux is small and directed towards the Earth. Interpretation: Cluster is generally earthward of NENL Observation 1. Background data  Poynting flux is small and directed towards the Earth. Interpretation: Cluster is generally earthward of NENL Observation 2. CLRs and CGRs are correlated with a strong Poynting flux towards the Earth (consistent). Observation 2. CLRs and CGRs are correlated with a strong Poynting flux towards the Earth (consistent). Interpretation: During times of increased PS energy conversion (ECRs observed), we observe increased Poynting flux (superposition) towards the Earth/ionosphere, where some energy may be dissipated in auroral processes (e.g. correlation between ECRs and AE, Kp). Hamrin, Nordic Cluster Meeting, 2011 Norm # ECRs Sx~0 Sx>0, towards Earth Sx<0, away from Earth Sx (GSM)

Observational evidence: Verifying the role of the PS as an important link in the chain of processes controlling energy conversion and transfer from the SW and to final auroral dissipation Observational evidence: Verifying the role of the PS as an important link in the chain of processes controlling energy conversion and transfer from the SW and to final auroral dissipation 1.Dayside reconnection is expected to be efficient during southward IMF. PS energy conversion should therefore correlate with IMF direction. Now this is experimentally verified! 2.Also verified that PS energy conversion correlates well with 2.1 earthward plasma flows and 2.2 earthward Poynting flux. Further discussions and suggestions? Splinter? Hamrin, Nordic Cluster Meeting, 2011