1. 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/NCAR Data Providers – SuperDARN, DMSP, Ground Magnetometers

2. CHAMP Neutral Density at ~400 km *10 -12 Kg/m 3 4 4 8 12 16 20 0 610 14 18 8 1216 20 6 10 14 18 0 DAYSIDE NIGHTSIDE Aug 24, 2005 (day 236)

3. CHAMP Neutral Density at ~400 km *10 -12 Kg/m 3 4 4 8 1216 20 0 610 14 18 8 1216 20 6 10 14 18 0 DAYSIDE NIGHTSIDE Aug 24, 2005 (day 236)

4. Aug 24, 2005 (day 236) “lobes” appear at 6-8 UT in both hemispheres 6UT Shock, By turns strongly +ve TIMEGCM CHAMP

5. Aug 24, 2005 (day 236) “lobes” appear at 6-8 UT in both hemispheres 9UT Bz turns south TIMEGCM CHAMP

6. BZ BY SW-VEL 0609 UT 06 09 UT

7. F15 07:51UT AMIE 07:50UT POTENTIAL JOULE HTG FAC AMIE (magnetometers, DMSP, SuperDARN) 5 min cadence

8. 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°

9. TIMEGCM CHAMP

10. TIMEGCM CHAMP

11. CHAMP Neutral Density at ~400 km *10 -12 Kg/m 3 4 4 8 12 16 20 0 610 14 18 8 1216 20 6 10 14 18 0 Southern Hem peak

12. TIMEGCM RHO N-HEM 0700 UT

13. BZ BY SW-VEL 0609 UT 06 09 1545 UT

14. F15 16:20 UT AMIE 16:20 UT POTENTIAL JOULE HTG FAC Note: Effect evident in AMIE as early as 15:45, but not seen by DMSP

16. TIMEGCM 17:00 UT RHOW (Vert. Wind)

17. F15 18:05 UT FAC AMIE 18:05 UT POTENTIAL JOULE HTG Morning Convection cell expanded

19. 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)