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National Space InstituteTechnical University of Denmark
TLEs: Combining Observations, Simulations, Theory and Instrument
Technical Aspects
Torsten Neubert
National Space Institute
Technical University of Denmark
National Space InstituteTechnical University of Denmark Overview
• Introduction– CAL/Europe– Space missions– Ground Campaigns
• Highlights of studies since last workshop– The source of sprites– The process of sprites– Effects of sprites on the atmosphere
• Lessons learned– Combinations of new instrumentation– The Internet is marvellous– Where are the blue jets?
• Preparations for TARANIS and ASIM– Models– Lab experiments– Campaigns
National Space InstituteTechnical University of Denmark Overview
• Introduction– CAL/Europe– Space missions– Ground Campaigns
• Highlights of studies since last workshop– The source of sprites– The discharge process of sprites– Effects of sprites on the atmosphere
• Lessons learned– Combinations of new instrumentation– The Internet is marvellous– Where are the blue jets?
• Preparations for TARANIS and ASIM– Models– Lab experiments– Campaigns
National Space InstituteTechnical University of DenmarkCoupling of Atmospheric Layers
• EU Research Training Network– 2002-2006– 10 young scientists– 11 research institutions in Europe
• Theme:– ”Do sprites affect the atmosphere or are they just beautifull like
rainbows”
• Strategy:– To combine new combinations of instrumentation and methods
• Outcome:– New science– Establish collaborations across Europe and across disciplines– The ASIM and TARANIS space missions
National Space InstituteTechnical University of Denmark ASIM and TARANIS
• Complementaty missions for studies of thunderstorm processes in the stratosphere and mesosphere
• ASIM: for the International Space Station (ESA)
• TARANIS: microsatellite (CNES)
• Both: Launch 2012
National Space InstituteTechnical University of Denmark
Ground Observations
National Space InstituteTechnical University of Denmark Overview
• Introduction– CAL/Europe– Space missions– Ground Campaigns
• Highlights of studies since last workshop– The source of sprites– The discharge process of sprites– Effects of sprites on the atmosphere
• Lessons learned– Combinations of new instrumentation– The Internet is marvellous– Where are the blue jets?
• Preparations for TARANIS and ASIM– Models– Lab experiments– Campaigns
Neubert. T. et al., Recent Results from Studies of Electric Discharges in the Mesosphere, submitted to Surveys in Geophysics
National Space InstituteTechnical University of Denmark Overview
• Introduction– CAL/Europe– Space missions– Ground Campaigns
• Highlights of studies since last workshop– The source of sprites– The discharge process of sprites– Effects of sprites on the atmosphere
• Lessons learned– Combinations of new instrumentation– The Internet is marvellous– Where are the blue jets?
• Preparations for TARANIS and ASIM– Models– Lab experiments– Campaigns
Neubert. T. et al., Recent Results from Studies of Electric Discharges in the Mesosphere, submitted to Surveys in Geophysics
National Space InstituteTechnical University of Denmark VLF signatures and Sprites
National Space InstituteTechnical University of Denmark IC discharges
National Space InstituteTechnical University of DenmarkThe E- field in the Mesosphere
• (A) 110 kA, 0.2 ms; 20 C; 200 Ckm• (B) 30 kA, 0.2 ms + 2 kA, 90 ms; 70 C; 700 Ckm
National Space InstituteTechnical University of Denmark Source summary
• The complete cloud discharge, including the IC components, are important for sprite morphology and location
• Modelling of the E-field in mesosphere is well underway• Valdivia, Cho and Rycroft, Steve Cummer ... and others
National Space InstituteTechnical University of Denmark Overview
• Introduction– CAL/Europe– Space missions– Ground Campaigns
• Highlights of studies since last workshop– The source of sprites– The discharge process of sprites– Effects of sprites on the atmosphere
• Lessons learned– Combinations of new instrumentation– The Internet is marvellous– Where are the blue jets?
• Preparations for TARANIS and ASIM– Models– Lab experiments– Campaigns
National Space InstituteTechnical University of Denmark
10 kHz (Stenbaek-Nielsen)
Sprite at High Speed
20 Hz
National Space InstituteTechnical University of Denmark Field Amplification in
Streamers
• The electric field is amplified in streamer tips
• Ek = background threshold field for streamer ignition
• Streamers may propagate in fields smaller than Ek
• Ecr- ~Ek / 2.5
• Ecr+ ~Ek / 6
National Space InstituteTechnical University of Denmark Comparison of Optical
Luminosity
• From 10 kHz imaging:– Streamer head: 109 - 1011 R
• PIC:– E=1.5 Ek
– Streamer head: 1.4 x 109 R
• Simulations are consistent with observatiions of the initial stage of the discharge.
Log Max Emisson Rate [R]9
8
7
6
2P1P1N
PIC 0-40 s
Stenbaek-Nielsen, grl 20080-2200 s
National Space InstituteTechnical University of Denmark
Properties of streamers at 70 km from PIC simulations
• Electric field: ~1.5 – 3.0 Ek• Conductivity: ~1 mS/m• Initial phase:
– Current density: ~100 mA/m2
– Energy deposition: ~10-5 J/m3/s
• Grown phase: ~100 times larger current (Steenbæk-N)• Sprite current = 1 kA Energy deposition: ~1 J/m• Sprite current = 10 kA Energy deposition: ~100 J/m
National Space InstituteTechnical University of Denmark Energetic electrons in
Streamers
National Space InstituteTechnical University of Denmark Overview
• Introduction– CAL/Europe– Space missions– Ground Campaigns
• Highlights of studies since last workshop– The source of sprites– The discharge process of sprites– Effects of sprites on the atmosphere
• Lessons learned– Combinations of new instrumentation– The Internet is marvellous– Where are the blue jets?
• Preparations for TARANIS and ASIM– Models– Lab experiments– Campaigns
National Space InstituteTechnical University of Denmark Infra sound from sprites
• Infra sound (1-10 Hz) observations give information on energy deposition into the neutral atmosphere
• Global network is part of Comprehensive Nuclear Testban Treaty Verification Programme
• Several stations are in France
National Space InstituteTechnical University of Denmark Sprite thunder at
1500 km distance
Sprite observed over Corsica on August 25 at 21:50:22.065
(Ip = +59.5 kA, +63.2 kA). Pressure perturbations and sonogram of infrasound observed at the Flers station 300 km North-West of Paris.
National Space InstituteTechnical University of Denmark Energy deposition
• Estimates have varied from MJ – GJ• Comparison with BOMB calculations: GJ• Pasko et al. based on infrasound obs: MJ-range• PIC simulations suggest MJ range
National Space InstituteTechnical University of Denmark Probing the mesosphere
and lower ionosphere
National Space InstituteTechnical University of Denmark EMP/ELVE pertubations
• Early fast• Caused by
lightning EMP
National Space InstituteTechnical University of Denmark IC/sprite perturbations
• Early-slow perturbation
• Caused by IC lightning electric fields and sprite
National Space InstituteTechnical University of Denmark Perturbations to the
mesosphere/ionosphere
• Models of perturbations from EMP and elves quite good (Inan group)
• IC discharges again showing up• Difficult to distinguish between effects of sprites and
fields radiated by the causative lightning activity.
National Space InstituteTechnical University of Denmark Perturbations to the
Chemistry
National Space InstituteTechnical University of Denmark Chemical effects of Sprites
• Significant effects of NO (and ozone) inside streamers• Small regional effects above severe thunderstorms• Negligable global effects
National Space InstituteTechnical University of Denmark Overview
• Introduction– CAL/Europe– Space missions– Ground Campaigns
• Highlights of studies since last workshop– The source of sprites– The discharge process of sprites– Effects of sprites on the atmosphere
• Lessons learned– Combinations of new instrumentation– The Internet is marvellous– Where are the blue jets?
• Preparations for TARANIS and ASIM– Models– Lab experiments– Campaigns
National Space InstituteTechnical University of Denmark Lessons learned
• Combinations of new instrumentation• The Internet is marvellous• Where are the blue jets?
National Space InstituteTechnical University of Denmark Overview
• Introduction– CAL/Europe– Space missions– Ground Campaigns
• Highlights of studies since last workshop– The source of sprites– The discharge process of sprites– Effects of sprites on the atmosphere
• Lessons learned– Combinations of new instrumentation– The Internet is marvellous– Where are the blue jets?
• Preparations for TARANIS and ASIM– Models– Lab experiments– Campaigns
National Space InstituteTechnical University of DenmarkIs our understanding of the mesosphere
above thunderstorms adequate?
100-200 km
10-15 km
70 km
In situ measurements in the mesosphere are difficult
Density and conductivity profiles?Small-scale irregularities?
National Space InstituteTechnical University of Denmark Some model development
• Electric field– EMP+QE– IC+CG
• The discharge process– Small scale coupled to large scale– Relativistic
• Effects on small-scale perturbations
National Space InstituteTechnical University of Denmark Laboratory
• X- and Gamma-rays from discharges
National Space InstituteTechnical University of Denmark Campaigns
• IC+CG lightning mapping• High-speed optical observations• Spectral observations of chemistry• Observations of ionisation/conductivity perturbations• Triangulation• Observations above thunderclouds
National Space InstituteTechnical University of Denmark New Science
• Already new insights into the nature of electric discharges
• Lightning represents and ”active” experiment probing the stratosphere and mesosphere. Understanding TLEs will give us a new tool to study the mesosphere, the least known region of the atmosphere