Simulated Response of the Magnetosphere-Ionosphere System to Empirically Regulated Ionospheric H + Outflows W Lotko 1,2, D Murr 1, P Melanson 1, J Lyon 1,3, M Wiltberger 2 1 Dartmouth College 2 NCAR/HAO 3 Boston University How does H + outflow influence MI coupling? – Some prior results – Empirically regulated outflow in the LFM global model – Event simulation – Diagnostics – Feedback between outflow and electron precipitation Conclusions Theory Program SM11D-08

Observational Statistics (Yau and André 97; Cully et al. 03; Lennartsson et al. 04) Outflow fluence increases – at higher altitude – for southward IMF – with greater SW P DYN Outflow energy increases – at higher altitude – with greater SW P DYN GW / hemisphere required to power the H + outflow Polar ions: 15 eV – 33 keV

Outflow without Precipitation (Winglee et al. 02) “Polar wind” outflow Any outflow reduces  PC O + outflow reduces  PC

Causal Driver for Ionospheric Outflow Empirical results derived from FAST cusp data near 4000-km altitude Strangeway et al. 05; Zheng et al. 05

Strangeway et al. ’02 Enhanced source population

 OUTFLOW ALGORITHM mW/m 2 LFM S || Auroral/Cusp Outflow F H|| #/m 2 -s Source “Regions” 0  1 #/m 2 -s LFM F e|| ~10 25 #/s Calibrate Fluence V || =F || /n #/m 2 -s Source-Weighted F H|| km/s V H|| n =  N Density Model N(r) (Gallager) (Strangeway) Empirical Formula Minimum (F e|| /F s, 1)

B y < 0 B z variable B x  0 P DYN  steady until 04:30 Event Simulation (CISM “Long Run”) v x  375 km/s IMF / SW at 20 R E

H + outflux at 2.25 R E B z, nT UT4 Mar 96 DUSK N S

NorthSouth Log (Flux, # / m 2 -s) simulation hours Average Number Flux Oct 97 – Mar 98 Polar perigee Log (Flux, # / m 2 -s) DUSK DAWN Lennartsson et al  ions/s3  ions/s2-3  ions/s FLUENCE

Where does the ionospheric H + go?

Control Volume Analysis Not to scale

Control Volume Analysis Not to scale

Control Volume Analysis Not to scale

Control Volume Analysis Not to scale

Mass Addition Diagnostics Mostly the inner magnetosphere Little persistence in Lobe and PS Mass addition is regulated by – IMF B z – IMF Variability Outflow latency is  20 minutes relative to IMF turnings

How does ionospheric H + outflow influence MI coupling?

– Higher density – Lower  || (and  e ) – Less e - energy flux – Lower  – Less FAC – Higher  PC MI Coupling Diagnostics Plasma addition at inner boundary  Joule dissipation  unchanged!

Feedback: Precipitation with Outflow “Drizzle” Energy “Beam” Energy “Robinson” Conductivity Precipitating Electron Flux Electron Energy Ionospheric Outflow MHD Variables MHD Variables

Conclusions Largest outflows when IMF B Z < 0 and variable Mass persistence in inner magnetosphere; less in outer regions H + outflow increases  PC while reducing I || Joule dissipation relatively unaffected! FEEDBACK between outflow-induced density enhancements and electron precipitation, conductivity dynamics