Transcript Slide 1
Localized Thermospheric Energy Deposition Observed by DMSP Spacecraft D. J. Knipp1,2, 1Unversity of Colorado, Boulder, CO, USA 2High Altitude Observatory, NCAR Boulder, CO, USA with contributions from: Y. Deng, L. Kilcommons, W. Li, J.Raeder, G. Crowley Data provided by E. Sutton, F Rich, G Wilson B Anderson Outline • Dayside Energy Deposition Background – Influence of IMF By on Poynting flux – Influence of low energy electrons • Local Combined influence of Poynting flux and Particles (outside of standard indices) • Future work – Global Combined Poynting Flux and Particle Flux • Observations • Models CHAMP Cusp Neutral Density Enhancement (2002-2005) North South Rentz 2009 and Forster, 2010 Poynting Flux -Neutral Density Comparisons Poynting Flux mW/m2 Southern Hemisphere Nov 2001Feb 2002 Slow Flow CMEs & Transients High Speed Flow CHAMP Neutral Density X 10--11kg/m3 Ionosphere-Thermosphere Energy Dissipation ~ 75% ~ 25% Courtesy of Jeff Thayer, CU Poynting Vector and Particles from Defense Meteorological Satellite Program S/C DMSP instruments sense Electric and Magnetic Fields Y ee - Spacecraft track X Z S E B DMSP S || Horizontal / 0 ( E x B y E y B x ) / 0 where E V B IGRF and B DMSP Horizontal B DMSP B Main DMSP Poynting Flux Changing IMF By Poynting flux exceeds that reported for intense substorms within a superstorm Knipp et al, GRL, 2011 Flank Reconnection Contributes to Neutral Density Enhancement IMF By is large Northern Hemisphere Example--Cont DMSP Poynting Flux Neutral Density from TIEGCM Joule Heating from AMIE Localized Energy Associated with Neutral Density Upheaval Crowley et al., 2010 TIEGCM Neutral Density compared to CHAMP satellite Flank Reconnection Contributes Poynting Flux when IMF By is large Northern Hemisphere Example 2 IMF By + Nov 7 2004 Li et al (2011) Southern Hemisphere Northern Hemisphere DMSP Extreme Poynting Flux |By| > 10 Bz < 0 mW/m2 mW/m2 By-N By+S 2000-2005 Each dot represents the maximum value of the of the pass Colored dots show Poynting flux in excess of 75 mW/m2 ~ 1500 passes are shown By+N By- S DMSP Extreme Poynting Flux |By| > 10 Bz >0 mW/m2 mW/m2 By-N By+S 2000-2005 Each dot represents the maximum value of the of the pass Colored dots show Poynting flux in excess of 75 mW/m2 ~ 1500 passes are shown By+N By-S Field Aligned Currents in the Cusp Strangeway et al., 2005 DMSP Poynting Flux Bz < 0 Poynting Flux mW/m2 -10 nT < Bz< -5 nT |By| < 5 nT Poynting Flux mW/m2 Fewer extreme values; Maybe associated with flow channel persistence -5 nT < Bz< 0 nT |By| < 5 nT Effects of Large East West IMF on the Cusp OPENGGCM MHD models and DMSP data show that east-west IMF promotes flank and or lobe merging that maps to cusp regions Movement of the open field lines resulting from this reconnection produces a pair of neighboring opposite FACs in the dayside ionosphere cusp region Closure of the FACs results in Joule heating in the ionospheric flow channel between the currents FAC locations are mainly controlled by the IMF clock angle. High speed solar wind flow enhances the Joule heating Joule heating in narrow, elongated channels may exceed 170mW/m2 When IMF By > 10 nT typical values of Poynting flux ~ 75mW/m2 Soft Particle Effects in Cusp DMSP Medium and Low Energy Particles (2004 Location of maximum energy deposition during each polar pass electrons 962-679 eV 462-317 eV 213-145 eV 100- 68 eV 46-32 eV electrons 962-679 eV 462-317 eV 213-145 eV 100- 68 eV 46-32 eV North 5-10nT By – Bz - South 5-10nT By + Bz- Particles with energies < 300 eV often ignored Poynting Flux-Density Relations in the Cusp At 400 km: 29% increase in Tn At 400 km: rise and fall of neutral mass At 200 km: 7% decrease in ρn At 400 km: 31% increase in ρn Difference in the thermosphere 3 hours after adding in the Poynting flux ( 75 mW/m2) GTM simulation by Deng et al 2011 Soft Particle Effects in Cusp At 200 km: 2% decrease in ρn At 400 km: 35% increase in ρn Difference in the thermosphere 3 hours after adding in the soft particle flux (100 eV, 2 mW/m2) GITM simulation (Deng et al. 2011) Poynting Flux and Soft Particle Effects in Cusp At 200 km: 4% decrease in ρn At 400 km: 50% increase in ρn Difference in the thermosphere 3 hours after adding in Poynting Flux and the soft particle flux (PF = 75 mW/m2, 2keV 0.3 mW/m2, 100 eV, 2 mW/m2) GITM simulation (Deng et al. 2011) Poynting Flux and Soft Particle Effects in Cusp 50% increase is < 31%+35%+5%, because the Poynting Flux and Particle Precipitation Effects are not Co-located ~50% neutral density enhancement is consistent with CHAMP obs Deng et al. 2011 Magnetosphere-Ionosphere Thermosphere Cusp Energy Global Currents North South Summary and Conclusions • Persistent near cusp CHAMP neutral density enhancement – Cusp Enhanced Poynting Flux (order of magnitude) • IMF By, solar wind flow speed & variability, pressure – Cusp Soft Particle Precipitation • IMF, solar wind flow speed & variability, pressure • These are NOT well described by geomagnetic indices • Global observations and modeling are key to future progress