What DMSP Data Tell us About the Thermosphere Response

to Solar Wind Forcing

Delores Knipp

CU Aerospace Engineering Sciences

and NCAR HAO

With Assistance from Liam Kilcommons, CSU

What DMSP Data Tell us About the ThermosphereResponse to Solar Wind Forcing

- Energy deposition on the dayside can be strongly controlled by the IMF By component

-Even during strong storms energy deposition on the dayside may exceed that on the nightside

-Orbit Integrated Poynting flux (and DMSP B) show the physical link between solar wind and neutral density periodicities

- During strong IMF By events magnetosheath particles are supplementing the energy deposition by Poynting flux…..but at a different altitude

- During high speed streams energy deposition on the dayside dominates that on the nightside

Adapted from Day, C., Spacecraft probes the site of magnetic reconnection in Earth's magnetotail, Physics Today, Vol. 54, No. 10, 16-17, 2001.

Adapted from NASA Press release: Connection of Sun's and Earth's magnetic fields provides energy for auroras, space weather, 2000.

Southward IMF Northward IMF

Schematics of magnetopause reconnection for IMF Bzillustrating the topological differences in reconnection location,

depending upon the interplanetary magnetic field direction.

Park et al., 2006

Merging location simulation

with dipole tilt of 30, IMF Bz = –5 nT, and IMF By = 5 nT.

0

180

90270

When IMF Bz is negative and By is present Merged flux tubes are accelerated azimuthally,

Dayside flow channel s develop between convections cellsR1 field aligned currents become asymmetric near noon

– Negative (dawnward) west,

Those connected to the southern (northern) hemisphere move duskward (dawnward)

Downward R1 currents dominate the noon sector in the northern hemisphere

- Positive (duskward) east,

Those connected to the southern (northern) hemisphere move dawnward (duskward)

Upward R1 currents dominate the noon sector in the northern hemisphere

N N

(Weimer, 2005 and Anderson, et al. 2008)

0

180

90270

0

180

90270

0

180

90270

0

180

90270

When IMF Bz is positive and By is present

Merged flux tubes are accelerated azimuthally, Dayside flow channel s develop but appear to be more variable

R1 field aligned currents become asymmetric near noon , R0 field aligned currents may be presentStrong IMF and high speed flow may provide more clarity

(Weimer, 2005 and Anderson, et al. 2008)

Poynting Vector from Defense Meteorological Satellite Program S/C

MainDMSPHorizontalDMSPIGRF

xyyx

HorizontalDMSP

where

BEBES

BBBBVE

BES

and

/)(

/

0||

0

DMSP instruments sense Electric and Magnetic Fields

Y

XZ

Spacecraft track

Cusp reconnectionnear the dawn flank

Field lines map acrossdayside

Near-Cusp energy source during strong IMF By: Li et al.

Southern lobe field lines

Obs DMSP Mag Perturbations

Calculated DMSP Poynting FluxOPENGGCM Joule Heating SH

SH

SH

Bz ~+10nTBY ~+25nTVSW ~ 950 km/s

OPENGGCM FAC

0

180

90270

Poynting Flux

Delta Bx Delta By

Vy

DMSP Data and Calculations

Aug 24 2005 Large IMF By, Bz~0

Neutral Density

Crowley et al., 2010

Poynting Flux Particle Flux

Vz

DMSP Data and Calculations

….not quite the full story…..

High-Latitude Energy Input: Field and Particles

Poynting Flux Particle Flux

Poynting Flux Particle Flux

Vz

DMSP Data and Calculations

….not quite the full story…..

2005

Poynting Flux and Solar Wind Speed

Lomb-Scargle Periodogram

DMSP F-15 Orbit Integrated |dBy| for 2005

Blue = angles in the range 90-180 , typical away or positive polarity. Red denotes angles in the range 270-360 ., typical toward or negative polarity. Yellow denotes angles in either of the other two azimuthal quadrants.

Orb

it In

tegr

ated

dB

y

DMSP F-15 Orbit Integrated dBy for 2005

Blue = angles in the range 90-180 , typical away or positive polarity. Red denotes angles in the range 270-360 ., typical toward or negative polarity. Yellow denotes angles in either of the other two azimuthal quadrants.

Orb

it In

tegr

ated

dB

y

Intense Magnetic Storm Jan 21-22 2005

High-speed StreamAugust 15-16 2005

AMIE Joule Heating and Electric PotentialDuring High Speed Flow

00 UT 16 Aug 2005

Courtesy of G. Crowley

AMIE Joule Heating and Electric PotentialDuring High Speed Flow

04 UT 16 Aug 2005

Courtesy of G. Crowley

AMIE Joule Heating and Electric PotentialDuring High Speed Flow1040 UT 16 Aug 2005

Courtesy of G. Crowley

AMIE Joule Heating and Electric PotentialDuring High Speed Flow2045 UT 16 Aug 2005

Courtesy of G. Crowley

What DMSP Data Tell us About the ThermosphereResponse to Solar Wind Forcing

- Energy deposition on the dayside is strongly controlled by the IMF By component

-Even during strong storms energy deposition on the dayside may exceed that on the nightside

-Orbit Integrated Poynting flux (and DMSP B) show the physical link between solar wind and neutral density periodicities

- During strong IMF By events magnetosheath particles are supplementing the energy deposition by Poynting flux…..but at a different altitude

- During high speed streams energy deposition on the dayside dominates that on the nightside