Thermospheric Density Enhancements from
Unexpected Energy Deposition During Bz North and Strong By Conditions
Geoff Crowley, ASTRA
Delores Knipp, NCAR
Kelly Ann Drake , USAF Academy
Jiuhou Lei, CU
Thanks
TIMEGCM /AMIE – Art Richmond/NCARData Providers – SuperDARN, DMSP, Ground Magnetometers
CHAMP Neutral Density at ~400 km
*10-12Kg/m3
*10-12Kg/m3
4
4 8 12 16 20 06 10 14 18
8 12 16 206 10 14 18 0DAYSIDE
NIGHTSIDE
Aug 24, 2005 (day 236)
CHAMP Neutral Density at ~400 km
*10-12Kg/m3
*10-12Kg/m3
4
4 8 12 16 20 06 10 14 18
8 12 16 206 10 14 18 0DAYSIDE
NIGHTSIDE
Aug 24, 2005 (day 236)
Aug 24, 2005 (day 236)“lobes” appear at 6-8 UT in both hemispheres
6UTShock, By turns strongly +ve
TIMEGCMCHAMP
Aug 24, 2005 (day 236)“lobes” appear at 6-8 UT in both hemispheres
9UTBz turns south
TIMEGCMCHAMP
BZ
BY
SW-VEL
06 09 UT
06 09 UT
F15 07:51UTAMIE 07:50UTPOTENTIAL
JOULE HTGFAC
• AMIE (magnetometers, DMSP, SuperDARN)• 5 min cadence
TIMEGCM 08:00 UT
Neutral Density(RHO)
Vert. Wind (W)
TIMEGCM forced with AMIE high latitude fields
• AMIE (magnetometers, DMSP, SuperDARN)• 5 min cadence
Outer Lat = 2.5°
TIMEGCMCHAMP
TIMEGCMCHAMP
CHAMP Neutral Density at ~400 km
*10-12Kg/m3
*10-12Kg/m3
4
4 8 12 16 20 06 10 14 18
8 12 16 206 10 14 18 0
Southern Hem peak
TIMEGCMRHON-HEM
0700 UT
BZ
BY
SW-VEL
06 09 UT
06 09 1545 UT
F15 16:20 UTAMIE 16:20 UTPOTENTIAL
JOULE HTGFAC
Note: Effect evident in AMIE as early as 15:45, but not seen by DMSP
TIMEGCM 17:00 UT
RHO W (Vert. Wind)
F15 18:05 UT
FAC
AMIE 18:05 UTPOTENTIAL
JOULE HTG Morning Convection cell expanded
CONCLUSIONS Poynting Flux Enhancements
• CHAMP sees unexpected density enhancements for BZ-north and strong BY events
• DMSP sees strong Poynting flux enhancements at very high latitudes (Delores)
• AMIE provides a global framework to confirm PF events
Poynting Flux Enhancements
• TIMEGCM densities often mimic CHAMP observations
• TIMEGCM reveals PF-events produce large density enhancements
• Density enhancements tend to be isolated at high latitudes
Density decrease
• Long-lived event from 16-24 UT produces density ‘hole’
• Density decrease measured by CHAMP
• Hypothesis: depletions due to dynamical effect (Crowley - cells)
Gravity Waves
• Large-scale gravity waves evident in TIMEGCM correspond to other
CHAMP density structures (not discussed in detail)