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)