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