Mitsuteru SATO (1), T. Ushio (2),

Transcription

1 Mitsuteru SATO (1), T. Ushio (2), T. Morimoto (3), H. Kikuchi (2), Y. Takahashi (1), M. Mihara (1), Toru Adachi (4), M. Suzuki (5), A. Yamazaki (5), U. Inan (6), and I. Linscott (6) 1. Hokkaido University, Japan 2. Osaka University, Japan 3. Kinki University, Japan 4. Meteorological Research Institute, Japan 5. ISAS / JAXA, Japan 6. Stanford University, Stanford, CA, USA #1

2 JEM-GLIMS JEM-GLIMS (Global Lightning and sprite MeasurementS on JEM-EF) Lightning and TLEs observation from Japanese Experiment Module (JEM), Exposed Facility (EF), ISS. Sprites NHK Objectives 1. Nadir observations of lightning and TLEs from ISS/JEM-EF, 2. Identification of sprite spatial distribution and generation mechanism, 3. Global survey of TLE occurrence. #2

3 What is TLEs? Transient Luminous Events (TLEs) : Lightning-excited transient discharge phenomena in the mesosphere Watch here!! NHK #3

4 What is TLEs? Sprite : One of the occurrence type of TLEs. alt. (km) First discovered in Occurring in km alt. Always excited by strong cloud-to-ground lightning discharges Most frequently observed. NHK #4

5 What is TLEs? Occurrence types of TLEs. #5

6 What is the Generation Mechanism? Quasi-Electrostatic (QE) Field Model Most of the observational facts can not be explained only by the simple QE model. [Pasko et al., 1997] We need more accurate generation mechanism of sprites. The reason determining the horizontal distribution of sprites is still big mystery since the discovery of sprites. Nadir observation is essentially effective. #6

7 What is the Occurrence Rates? Global Occurrence Rates of Lightning OTD / MicroLab-1 LIS / TRMM We do not know the global occurrence rates and distributions of TLEs... ISS has 51 orbital inclination. Lighting and TLE observation by scanning all the local time area!! ISS is an ideal platform for the lightning and TLE observations. #7

8 What is the Chemical Impact of TLEs? Chemical Impact of Sprites on Earth s Atmosphere NOx production by sprites We can evaluate chemical impact of TLEs on Earth s atmosphere!! Global occurrence rates and distributions of TLEs #8

9 GLIMS Instruments Name ID Specification CMOS Camera (optical) Photometer (optical) LSI PH Two CMOS cameras 512x512 pixels, FOV= , fps = 29 (122, 488), 10 bit resolution, LSI-1: = 762+/-5 nm, LSI-2: = nm 6 channel photometers = nm, 316+/-5 nm, 337+/-5 nm, 392+/-5 nm, = 762+/-5 nm, nm f s = 20 khz, FOV=43, 12 bit resolution VLF Receiver (EM) VHF Interferometer (EM) Science instrument Handling Unit VLFR VITF SHU 1 set of VLF antenna and a receiver f = 1-40 khz, f s = 100 khz, 16 bit resolution, 15cm monopole antenna 2 sets of VHF antennas and a receiver f s = MHz, 8 bit, patch antenna, baseline=1.5 m Onboard computer Power control, Event triggering, Data acquisition & handling, Command/telemetry I/F, Data compression #9

10 LSI LSI (Lightning and Sprite Imager) 2 CMOS cameras (wide-band / narrow-band filter) LSI-1 : wide-band filter (lightning) LSI-2 : narrow-band filter (TLEs) LSI-1 LSI-2 Item Wavelength Value nm (LSI-1) 762+/-5 nm (LSI-2) FOV Optics Detector F=1.4, f=25mm CMOS (STAR-250) Pixel Number Sensitivity 6.9E-6 W/m 2 Resolution Spatial Resolution Time Resolution Table. Summary of LSI specification. 10 bit 0.4 ground surface 34.5 ms (29fps) Fig. Picture of LSI flight model. #10

11 LSI Lightning Spectrum Alt. [km] 400 ISS altitude 762nm 100 Sprite Spectrum(N 2 1PG) 762nm 10 O 2 #11

12 PH 2 photometer units (PH-U) Absolute intensity measurement of N 2 1P, 2P, N 2 + 1N emission lines Item Table. Summary of PH specification. Value Wavelength nm 337+/-5 nm 762+/-5 nm nm 316+/-5 nm 392+/-5 nm PH1 PH2 PH3 PH4 PH5 PH6 N 2 LBH N 2 2P (0,0) N 2 1P (3,1) N 2 2P (0,0) N 2 2P (1,0) N 2 + 1N (0,0) FOV for PH1-3,5,6 for PH4 Detector PMT (R7400) PDD (S1227) for PH1-3,5,6 for PH4 HV Range Resolution Sampling Freq. 0.1E-6 W/m 2 for PH1-3,5,6 10E-6 W/m 2 for PH V 12 bit 20 khz Fig. Picture of PH Unit #1 (top) and PH Unit #2 (bottom). #12

13 PH N 2 LBH spectrum of sprites Alt. [km] 400 ISS altitude nm 100 Atmospheric transmittance nm O 3 10 #13

14 VLFR VLF Receiver Detection of whistler wave generated by lightning Table. Summary of VLFR specification. Item Freq. Range Resolution Sampling Freq. Antenna Value 1-30 khz 14 bit 100 khz monopole antenna (15cm) Fig. Picture of VLFR electronics (top) and VLFR antenna (bottom). Fig. Schematic illustration showing the propagation of whistler waves. #14

15 VITF VHF Interferometer (VITF) Measurement of VHF pulses excited by lightning Item Table. Summary of VITF specification. Value Freq. Range Resolution Sampling Freq. Antenna MHz 8 bit 200 MHz patch-type antenna Fig. Picture of VITF electronics (top) and VITF antennas (bottom). Fig. Development of lightning currents derived from VHF interferometer data. #15

16 GLIMS Instruments VLFR antenna PH-U1 PH-U2 LSI-1 LSI-2 SMA connectors for VITF antennas Fig. Picture of GLIMS flight model. #16

17 JEM-GLIMS and MCE Multi-mission Consolidated Equipment (MCE) SIMPLE REX-J IMAP/VISI HDTV IMAP/EUVI GLIMS/VITF-ANT GLIMS/VLFR-ANT GLIMS/LSI GLIMS/PH Nadir GLIMS/VITF-ANT #17

18 Mission Status 2012 Jul. 21 Jul. 27 Aug. 9 JEM-GLIMS was launched by H-IIB rocket and HTV-3 cargo ship HTV-3 docked with ISS MCE was installed at JEM Exposed Facility (EF) GLIMS initial checkout operation started Sep. 15 Nov. 12 Initial checkout operation completed, and started test observation Parameter studies for event triggering Nominal operation started Nov Continuous observation and data acquisition 2014 #18

19 JEM-GLIMS Lightning Events Period : 2012/ 11/ / 01/ 31 3,130 events 2012/12/25 12:49:04UT 2013/01/01 19:36:17UT 2013/01/30 04:20:58UT 2013/03/22 22:10:47UT 10km 10km 10km 10km 2012/12/29 00:16:20UT 2013/01/18 17:04:59UT 2013/02/11 02:45:02UT 2013/03/29 13:20:05UT 10km 10km 10km 10km #19

20 Global Map of Triggered Events Period : 2012/ 11/ / 01/ 31 3,130 events South Atlantic Anomaly (SAA) #20

21 Seasonal Variation Northern Summer (June, July, August) South Atlantic Anomaly (SAA) #21

22 Seasonal Variation Northern Winter (December, January, February) South Atlantic Anomaly (SAA) #22

23 Sprite Event / Outline of the Event 2013/09/28 19:50: Central Africa Frame 1 (T trigg. =-33ms) nm LSI-1 762±5nm LSI-2 PH nm Trigger Occurrence of TLEs 20 km PH2 337nm Frame 2 (T trigg. = 0ms) PH3 762nm Frame 3 (T trigg. =+33ms) Frame 4 (T trigg. =+66ms) PH4 PH5 PH nm 316nm 392nm [ms] #23

24 Sprite Event / Image Subtraction Frame 2 (T trigg. = 0ms) LSI-1 Image Subtracted Image Existence of the fine structures!! Frame 3 (T trigg. =+33ms) 20 km 20 km #24

25 Sprite Event 2013/12/21 05:08: Mexico, Middle America Frame 3 (T trigg. = +33 ms) LSI-1 Image Subtracted Image image with LSI-1 Image 10 km 10 km Detailed horizontal structure of sprites is first identified!! #25

26 Elves Event / Outline of the Event 2013/09/08 16:57: Southern Australia Frame 1 (T trigg. =-33ms) nm LSI-1 762±5nm LSI-2 PH nm Occurrence of TLEs 15 km PH2 337nm Frame 2 (T trigg. = 0ms) PH3 762nm Frame 3 (T trigg. =+33ms) Frame 4 (T trigg. =+66ms) PH4 PH5 PH nm 316nm 392nm [ms] #26

27 Elves Event / Interpretation Alt. [km] GLIMS FOV of PH (42.7 conical) (r=125km Elves FOV of LSI (160km ifov of LSI (0.3km Lateral expansion 10 Propagation of EMP CG discharge Due to the rapid lateral expansion (<1ms) and thin optical depth of the elves emission, LSI can not image elves (below the sensitivity). Due to the wide FOV and high sensitivity, PH can only detect elves signal. #27

28 Lightning Whistler 2013/09/09 13:04: UT Lightning emission Lightning whistler Time delay from the lightning can be reasonably explained by the propagation of whistler wave with a group velocity (Vg). Frequency Dispersion Electrical properties of lightning discharge. 28

29 VHF Pulses 2013/05/25 14:50: UT Lightning images (LSI) Light curve data of PH Detection number of VHF pulses Sample waveforms of VHF pulses First identification!! VHF pulses are mainly emitted by in-cloud lightning currents. We will estimate source location using interferometric technique. #29

30 Conclusion JEM-GLIMS is continuing nadir observations of lightning & TLEs from ISS, and it succeeded in detecting thousands of lighting events since Nov JEM-GLIMS succeeded in detecting sprite and elves events by the optical instruments. JEM-GLIMS also succeeded in detecting lighting whistler and VHF pulses, which enable us to identify the electrical properties of lightning discharges. Future Plan Comparison between GLIMS optical data and GLIMS/VLF and VHF data to clarify the generation mechanism of sprites, Identification of seasonal / LT dependences of TLE occurrences. #30

31 Appendix #31

32 Global Map of FUV Events PH1 Events = 365 Global Distribution of Possible TLEs Period : 2012/ 11/ / 01/ 31 South Atlantic Anomaly (SAA) #32

33 JEM-GLIMS and MCE MCE VITF Antenna #2 VITF Antenna #1 JAXA GLIMS GLIMS Main Instruments 2-channel CMOS cameras (LSI) 6-channel photometers (PH) VLF receiver (VLFR) 2-sets of VHF receivers (VITF) PH Unit1 PH Unit2 LSI VLF Antenna #33

34 SHU SHU (Science instruments Handling Unit) Power control (power, A/D) Event trigger, data acquisition GPS synchronization data compression: HIREW (lossless) Command and telemetry interface Item Main Function FPGA Table. Summary of SHU specification. Value Power control Data acquisition Event trigger Data compression (HIREW encoding) GPS time synchronization Command, Telemetry I/F (RS422 I/F) Xilinx Vertex II CPU S-RAM Mass Memory SH2 8MB x 2 for FPGA (temporal data buffering) 8MB for CPU 128MB (FIFO memory for TLM) Fig. Picture of SHU flight model. #34

35 Sprite Event / Image Subtraction Frame 2 (T trigg. = 0ms) LSI-1 Image x (1/α) LSI-2 Image ave+5σ #35

36 Sprite Event / Absolute Intensity of PH Data Peak intensities of PH light curve data PH1 ( nm) PH2 (337nm) PH3 (762nm) PH4 ( nm) PH5 (316nm) PH6 (392nm) Peak Intensities nm: [W/m 2 ] 337nm: [W/m 2 ] 762nm: [W/m 2 ] nm: [W/m 2 ] 316nm: [W/m 2 ] 392nm: [W/m 2 ] [ms] #36

37 Occurrence Probability Occurrence Probability Sprite Event / Intensity Ratio, Occurrence Probability ISUAL Case GLIMS Lightning Case 337nm / Red( nm) 337nm / Red( nm) Log(Ratio) Log(Ratio) [ Adachi et al., AE33A-0317, this meeting ] Ratio (337 / Red) Occurrence probability of TLEs % % % % % #37

38 Relative Intensity Ratio Sprite Event / Intensity Ratio Relative Intensity Ratio toward PH4( nm) Intensity (337/Red): x Analyzed Event GLIMS Lightning Event Wavelength [nm] ( 337 / Red ) = x 26 ( 392 / Red ) = x 25 Occurrence Probability of TLEs 80% at (337/Red)=11.7 [ Adachi et al., AE33A-0317, this meeting ] #38

39 [ pt ] [ pt ] [ V ] Sprite Event / Electrical Properties of Parent CG Trigger time = [sec] GLIMS data PH [sec] Esrange (Kiruna) 40 0 NS-comp Possible CG Time = [sec] EW-comp Δt = 35.6 ms (8.5 v=0.8c) 0 ELF data Syowa (Antarctica) NS-comp EW-comp Δt = 43.0 ms (10.4 v=0.8c) [sec] #39

40 Sprite Event / Electrical Properties of Parent CG Propagation Paths of the ELF Waves Esrange Propagation Location of the sub-satellite point (SSP) ( E, N) 7.0 Mm Cross point of the two great circles Distance between sub-satellite point (SSP) and ELF stations SSP Esrange = 7.0 Mm Sub-satellite point ( E, N) 8.5 Mm Syowa Propagation SSP - Syowa = 8.5 Mm Actual distances between SSP and ELF stations are comparable to these derived from propagation time of the ELF waves. Cross point of the two great circles and sub-satellite point are very close. #40

41 Sprite Event / Electrical Properties of Parent CG Charge Moment Change (CMC) Estimation Current Moment Spectrum Current Moment Spectrum (ESR data) Assumed Current Moment Waveform H Φ (f) : Idl(f) : I 0 dl : θ : R E : h 0 : n : ν : P m : τ : observed magnetic filed spectrum current moment spectrum peak current moment angular distance radius of the Earth wave reflection height mode number propagation coefficient Legendre polynomial time constant of the lightning current Current Moment Waveform (ESR data) CMC = [C km] Station CMC Esrange Syowa [C km] [C km] Enough to excite sprites!! #41

42 FOV of LSI and PH Field-of-view (FOV) of LSI and PH FOV of PH4 (86.8 o, conical) 210 km FOV of PH1-3, PH5, PH6 (42.7 o, conical) 210 km 156 km 378 km FOV of LSI (28.7 o x 28.7 o, square) #42

43 FUV Emission and Atmos. Transmittance PH1 signals are originated from N 2 Lyman-Birge-Hopfield (LBH) emission. Sprites can emit N 2 LBH emission [Gordillo Vázquez et al., 2011; Kuo et al., 2007; Chang et al., 2010]. Lightning FUV emission may not reach ISS altitude due to the severe O 3 absorption. It this event related to TLEs??? N 2 LBH Spectrum of Sprite Halo Fig. Simulated N2 LBH spectrum of sprite halo [Gordillo Vázquez et al., 2011]. Fig. Calculated atmospheric transmittance in the visible range. #43