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J. M. Forbes, E. K. Sutton, R. S. Nerem

Department of Aerospace Engineering Sciences, University of Colorado, Boulder, Colorado, USA

Sean Bruinsma, CNESToulouse, France

Thermosphere Density and Wind Responses to Solar and Geomagnetic Activity

GRACE-A & GRACE-B• launched in March 2002• 3.12 m x 1.94 m x 0.78 m • 500 km altitude• near-circular (89.5°) orbits • GRACE-B ≈ 220 km behind GRACE-A

Supported by NSF Space Weather Grant ATM-0208482

The CHAMP satellite was launched in July 2000 at 450 km altitude in a near-circular orbit

with an inclination of 87.3°

The physical parameters of the CHAMP satellite are:• Total Mass 522 kg • Height 750 mm• Length (with 4044mm Boom) 8333 mm • Width 1621 mm• Area to Mass Ratio 0.00138 m²kg

CHAMP is in a 13:20/01:20 LT orbit during the Super Storms

Local time precession rate of CHAMP is about 24 hours/133 days

The GRACE satellites are in a 16:00/04:00 LT orbit during the Super Storms

The “Halloween 2003” Intense Solar Events

Active region 10486, already under close scrutiny by several instruments on SOHO and other satellites, as well as numerous ground observatories, started up a spectacular two-part show in the morning on Tuesday 28 October 2003. An X 17.2 flare, the second largest flare observed by SOHO, was setting off a strong high energy proton event and a fast-moving Coronal Mass Ejection, hitting Earth early on Wednesday 29 October. The one-two punch was a done deal on Wednesday afternoon, when an X 10.0 flare set off another round of particles and another fast-moving CME.

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Thermosphere Density Response

~200-300%

Second CME

arrives

First CME

arrives

Oct 27

Oct 28

EUV flare

arrives

~200%

19 hrs

Vic Winter, Warrensburg Missouri, Oct 30: The first wave of aurora appeared between 01 and 02 hours UT. A second wave hit about 04 hours UT and had many red spikes with green curtains below."

Barry Kierstein, Lyndeborough, New Hampshire , Oct. 30

Aurora during theHalloween Storms

Thermosphere Wind Response to the October/November 2003 Storms from CHAMP

Accelerometer Measurements

Westward winds during quiet period

Westward intensification during disturbed periods

Daytime (LST ~ 13:20) Zonal Winds at the Equator

Note: longitude also changing @ 360°/day

CHAMP ~ 0 to -50 m/s during quiet period

HWM93 ~ 50 to 100 m/s during quiet period

CHAMP strong westward intensification during disturbed periods

Nighttime (LST ~ 01:20) Zonal Winds at the Equator

Suggests enhanced eastward electric field, vertical drifts, and vertical redistribution of equatorial plasma -- reduction or increase in east-west drag at 410 km?

TEC asymmetry possibly imply northward wind?

Equatorial plasma depletion reduces ion drag?

Reduction in O/N2 ratio or transport effect?

TEC Measurements Suggest a Possible Combination of Electrodynamic, Dynamical and Chemical Effects at the Equator

Credit: International GPS Service - http://igscb.jpl.nasa.gov

X17flare301

Oct 28X28flare308

Nov 4

302, 303Oct 29, 30

324Nov 20

(days)

The Isolated Magnetic Storm of November 20, 2003

(days)

V2

Bz

ap

Dst

Oct25

Oct30

Oct20

Nov20

Day of Year, 2003 Day of Year, 2003

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Smoothed densities, using a 150-sec (~1200 km) window, along the orbital tracks of GRACE (left) and CHAMP (right) on dayside (top) and nightside (bottom) beginning during the quiet period early on day 324, and ending during the quiet period early on day 325. The dotted black curves are beginning orbits and the solid black curves are ending orbits while the color rainbow spectrum (from dark blue to red) represents the sequence of orbits during the storm.

Large-Scale Wave Structures during the Storm

Traveling Atmospheric Disturbances during the 15-24 April 2002 Magnetically Active Interval

waves launched

~800 ms-1

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