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 Thermosphere Response 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, Adapted from NASA Press release: Connection of Sun's and Earth's magnetic fields provides energy for auroras, space weather, Southward IMFNorthward IMF Schematics of magnetopause reconnection for IMF Bz illustrating 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

When IMF Bz is negative and By is present Merged flux tubes are accelerated azimuthally, Dayside flow channel s develop between convections cells R1 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)

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 present Strong 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 DMSP instruments sense Electric and Magnetic Fields Y X Z Spacecraft track

Cusp reconnection near the dawn flank Field lines map across dayside Near-Cusp energy source during strong IMF By: Li et al. Southern lobe field lines Obs DMSP Mag Perturbations Calculated DMSP Poynting Flux OPENGGCM Joule Heating SH SH B z ~+10nT B Y ~+25nT V SW ~ 950 km/s OPENGGCM FAC

Poynting Flux Delta BxDelta By Vy DMSP Data and Calculations

Aug Large IMF By, Bz~0 Neutral Density Crowley et al., 2010

Poynting FluxParticle Flux Vz DMSP Data and Calculations ….not quite the full story…..

High-Latitude Energy Input: Field and Particles Poynting FluxParticle Flux

Poynting FluxParticle 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 |dB y | for 2005 Blue = angles in the range , typical away or positive polarity. Red denotes angles in the range ., typical toward or negative polarity. Yellow denotes angles in either of the other two azimuthal quadrants. Orbit Integrated dBy

DMSP F-15 Orbit Integrated dB y for 2005 Blue = angles in the range , typical away or positive polarity. Red denotes angles in the range ., typical toward or negative polarity. Yellow denotes angles in either of the other two azimuthal quadrants. Orbit Integrated dBy

Intense Magnetic Storm Jan

High-speed Stream August

AMIE Joule Heating and Electric Potential During High Speed Flow 00 UT 16 Aug 2005 Courtesy of G. Crowley

AMIE Joule Heating and Electric Potential During High Speed Flow 04 UT 16 Aug 2005 Courtesy of G. Crowley

AMIE Joule Heating and Electric Potential During High Speed Flow 1040 UT 16 Aug 2005 Courtesy of G. Crowley

AMIE Joule Heating and Electric Potential During High Speed Flow 2045 UT 16 Aug 2005 Courtesy of G. Crowley

What DMSP Data Tell us About the Thermosphere Response 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