# Presentation: 808725

## Overwhelming Auroral Wind O+ Contribution to Plasma Sheet (Halloween 2003 Storm)

- M Nosé, S Taguchi, K Hosokawa, S P Christon, R. McEntire, T E Moore, M R Collier,
- JGR, in press, 2005
- T E Moore, M-C Fok, S P Christon, S Chen, M O Chandler, D C Delcourt, J Fedder, S Slinker, M W Liemohn,
- GM 1064, in press, 2005

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## Halloween Storm “DST”

- BRG bars refer to Geotail EPIC analysis periods, in what follows

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## Geotail Passes (1 hr tics)

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## Epoch Data Plots

- BRG plots map to passes per previous
- First O+ enhancement preceeds main phase
- Largest enhancement during rising phase to maximum
- Bx reversal at Geotail indicates neutral sheet crossing, spatial effects

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## EPIC Energy

- Same BRG ordering
- (a), (b) early
- (c), (d) late
- See accumulating flux at higher energy first, then lower

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## Partial pressure ratio (Red Trace)

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## Halloween 2003 on DST Trend

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## TIDE Outflow Observations

- Polar perigee pass occurs near peak ring current
- Largest outflow flux event seen by Polar in dayside cusp: 1.5x1010 cm-2s-1 =
- 10 x 24-25 Sept 1998 IME
- Nightside auroral outflow comparable but cooler

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## Solar Wind Driven Auroral Wind: Response to Dynamic Pressure Increase

- Motivation
- Responses to protoyptical solar wind disturbances
- Model single particles in MHD fields from LFM
- Auroral Wind (O+) considered here (see below for solar, polar wind)
- Auroral Wind fluxes driven by MHD ionospheric b.c.
**S** and Ne-Hot drive flux; **S** drives ion Eth; J// drives ion E//
- Pd enhancement by order magnitude in 5nT By only solar wind
- Results
- Pre-existing IMF By producing substantial convection at 0.4 nPa
- Sets off substorm shortly after pressure jump to 4.5 nPa
- Dynamic ionospheric boundary conditions drive large outflows
- Produces ring current-like pressure increase
- Moore, Fok, et al., JGR Feb 2005 “Solar and Polar Wind...”
- Moore, Fok, et al., AGU Monograph 1064, 2005
- Dynamic boundary conditions manuscript in preparation

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## Model Setup and Solar Wind Trajectories

- Delcourt [1993] full equations of motion w/ g
- 4th order Runge-Kutta
- Time step 5 ̊ gyrophase
- Linearly interpolated MHD fields from LFM simulation
- Spherical MHD grid with axis along Xgsm.
- Polar resolution 2 ̊
- Azim resolution 5.5 ̊
- Radius varies with r, Polar

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## Dynamic Particle Boundary Conditions: Pd increase

- Eperp (Poynting Flux) 	Eparl (J// and Knight) 	Escape Flux (Ne + **S**)

- North

- South

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## Dynamic Auroral Wind: Pd Increase

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005

## CONCLUSIONS

- Global auroral wind circulation linked to localized, dynamic boundary condsitions from MHD per Strangeway et al. [2005], Zheng et al. [2005]
- Pre-existing auroral wind O+ outflows are highly compressed by solar wind pressure increase
- O+ outflow increases with pressure increase, but arrival delayed
- Auroral wind O+ inflates plasma sheet and inner magnetosphere
- Largest geospace storms supported by atmospheric ablation
- Future Work
- Move to global simulations with ionospheric plasmas as dynamical elements, e.g. Winglee code

- T E Moore, NASA GSFC

- Polar Telecon 16 Sept 2005