高时间分辨精灵成像仪：观测与启示(英文ppt).ppt

Leiden,October 2007,High Time-Resolution Sprite Imaging:Observations and Implications,H.C.,Stenbaek,-Nielsen,Geophysical Institute,University of Alaska Fairbanks,M.G.,McHarg,U.S.Air Force Academy,Leiden,October 2007,This,ppt,version was prepared for conference web site posting.,There are no animations in this version.Animations have,been replaced with a representative image,and some additional,explanatory text has been added.,I will be preparing compressed version of animations.,(Most are too large for email),Some are available with our publications through,AGUs,journal website:,McHarg,et al.GRL,34,L06804,doi:10.1020/2006GL027854,2007,Stenbaek,-Nielsen et al.,GRL,34,L11105,doi:10.1029/2007GL029881,2007,For further info contact us by email:,hnielsengi.alaska.edu,Leiden,October 2007,Trans Luminous Events(TLE),Elve,:1 ms,E&M pulse,Halo:1-5 ms:,glow discharge,Sprite:1-10 ms;,streamer discharge,Afterglow:1-200 ms,chem.processes,Blue jets,beads,crawlers,ambers etc.:,5-1000ms,process?,Leiden,October 2007,2 examples at 1000 fps,Sprite dynamics,Images show features well known from TV image sequences with better detail,Halo,tendrils,branches,and beads,Images colorized for emphasis,Altitude scale derived assuming sprite to be at lightning strike(NLDN),Leiden,October 2007,Sprite at 1000 fps,Sequence:15 ms.,Selected frames from animation,Animation,Leiden,October 2007,Sprite at 1000 fps,Sequence:30 ms.Note:No halo with second sprite,Animation,Selected frames from animation,Leiden,October 2007,Rebrightening,Leiden,October 2007,Features to be addressed,Time scales,Branches 1 ms,Tendrils 1 ms (not resolved at ms),Image:18 Aug 1999,WIRO,Wy,.,Leiden,October 2007,Effect of frame rate9 July 2005 06:06:46 UT,Streamers(almost)resolved at 50,s(20,000 fps),33 ms video,1 ms,50,m,s,10,000 fps makes a lot of difference.,Leiden,October 2007,Link to streamers in the lab,Exposure:300 ns 50 ns 10 ns 2 ns,Courtesy of Prof.Ute Ebert and T.,Briels,of TU,Eindhoven,Netherlands,Leiden,October 2007,Scaling of process time,Time development scales as 1/n,Density at ground level:3 10,19,/cc,Density at 80 km altitude:3 10,14,/cc,Scaling factor:10,5,Leiden,October 2007,Scaled to 80 km altitude,30 ms(TV)5 ms 1 ms 0.2 ms,33 fps 200 fps 1000 fps 5000 fps,Leiden,October 2007,Scaled to 80 km altitude,30 ms(TV)5 ms 1 ms 0.2 ms,33 fps 200 fps 1000 fps 5000 fps,10,000 fps makes a lot of difference.,Leiden,October 2007,Streamer head formation,First downward,later upwards moving streamer heads,Upward starts from,Lower altitude,Existing luminous sprite structures,(animation:GRL,34,11,2007),9 ms image sequence,Animation,Leiden,October 2007,Streamer head formation,9 July 2005 06:33:11 UT:10,000 fps Gating 50 s Duration 5.0 ms,Downward streamers first,Upwards streamers later and,-from lower altitude,-from existing structure,Streamer velocity up to 0.3 c,Animation,Leiden,October 2007,Streamer head formation,Downward streamers first,Upwards streamers later and,-from lower altitude,-from existing structure,Streamer velocity up to 0.3 c,7 July 2005 08:31:20 UT:5,000 fps Gating 100 s Duration 5.0 ms,Animation,Leiden,October 2007,Downward Streamer,Summary of downward streamers:,Streamer head starts 70-90 km altitude,Halo may or may not be present,Streamer head brightens as it moves down,Direction largely,straight down,Velocity up to 6 10,7,m/s,Both increase and decrease in speed observed,Leiden,October 2007,Upward Streamer,9 July 2005,04:15:17 UT,10,000 fps,Animation,Leiden,October 2007,Upward Streamer,Summary of upward streamers:,Not present in all events,Starts later than downward streamers,Starts at lower altitude than downward streamers,Starts from bead structures,Ends with a“puff”and upward motion stops,Velocities similar to downward streamers,Significant,horizontal velocity,component,Leiden,October 2007,Morphology,C-sprite,Downward streamers,No upward streamers,Carrot sprite,Downward streamers,Upward streamers,Leiden,October 2007,Main Points,All sprites start with downward moving streamer heads,Streamer heads are small.Appear in images just like background stars,Individual streamer heads move in one direction only,No example of double headed streamers,No evidence of geomagnetic field effects,Leiden,October 2007,Streamer head brightness,Streamer heads:,Gaussian profile,Similar to stars,Smaller than spatial resolution,Point sources,Stellar,mag,-6,Emission rates:,5 10,21,to 3 10,24,phot/s,Leiden,October 2007,Size,Smaller than our 150 m resolution,Telescope,obs,:10-200 m(,Gerken,et al.),Models 25 m (Liu and,Pasko,),Assuming 25 m size:,Average brightness:1 100 GR,Leiden,October 2007,Size,Assuming 8 10,11,#/cm3/s(,Sentman,et al.):,Size from 30 300 m,Leiden,October 2007,Streamer brightness presented is in the June 16 issue of GRL.,Reprints available here at meeting,Leiden,October 2007,Implications,Streamer heads very bright,Source of energy for local chemical processes(talk Friday by D.,Sentman,),Longer lasting effects?,Significant effects on the mesosphere?,Leiden,October 2007,Streamer head splitting,9 July 2005,06:33:11 UT,10,000 fps,Animation,Leiden,October 2007,Streamer head splitting,Splitting on the run,2005 data show splitting a slow process:,Individual streamer heads propagate 30 km,but only a few splitting events observed,Only 1 or 2 new streamer heads formed in each splitting,No slow down while splitting,But 2007 telescopic images show many and multiple streamer heads forming,Leiden,October 2007,Streamer head splitting,23 June 2007 07:01:01 UT,Langmuir,NM,10,000 fps,50,s exposures,Field of view:2.12x1.58 degrees,Altitude 80 km at 600 km range,Velocity:3 10,7,m/s,;Size:0.1 to 2 km,Animation,Leiden,October 2007,Streamer head splitting,23 June 2007 04:22:49 UT,10,000 fps,50,s exp.,Field of view:2.12x1.58 deg,Altitude 80 km at 600 km,Velocity:10,7,m/s,;,Size:0.1 to 2 km,Leiden,October 2007,Streamer head splitting,Preliminary analysis,Difficult to match with earlier larger FOV images,More splits,More streamer heads,Maybe the sequences are from the central part of the sprite,Animation,Leiden,October 2007,Afterglow,9 July 2005,04:38:00 UT,10,000 fps,Leiden,October 2007,Afterglow,Very little spatial motion,Vertical structure and brightness not as expected from streamer head brightness,Duration of afterglow vary between events,Energy beyond streamer heads alone,Can last from a few ms to several 100 ms,Total optical power may be larger than for streamer heads,Leiden,October 2007,Afterglow spectrum(300 fps),N2 1P spectra.Some altitude differences indicating additional local processes(,Kanmae,et al.,GRL,2007).,Leiden,October 2007,Streamer head spectrum,Slitless,spectroscpy,Star background.0,th,and 1,st,order spectra clearly seen.,Wavelength coverage 400-900 nm,Leiden,October 2007,Streamer head spectrum50,s,(20,000 fps),Primarily N2 1P,Leiden,October 2007,Atmospheric effects,Sprites were at 600-700 km so blue attenuated by x100,Leiden,October 2007,Optical spectra,Primarily N2 1P band emissions in both streamer heads and afterglow,Spectral altitude differences in afterglow,No N2 ion emissions detected(yet),Would expect differences between streamer heads and afterglow(not proven yet we are working on it),Chemical processes and their consequences,Leiden,October 2007,Delayed Sprite,Video(30 fps).FOV:21x16 degrees,Note:First one sprite then a large carrot sprite and finally some activity at lower altitude,1000 fps images covering the first sprite to the onset of the carrot sprite,(Left-right reversed.Sorry!),Animation,Animation,Leiden,October 2007,Lightning,Lightning at USAFA,66,000 fps(15,s),Distance?(very close!),Field of view:8x8 deg,Pix size:0.2 m,(200 m range),Thanks for your attention.,Leiden,October 2007,