Ionospheric studies using a network of all-sky imagers from equatorial to sub-auroral latitudes

Transcription

1 Ionospheric studies using a network of all-sky imagers from equatorial to sub-auroral latitudes C. Martinis, J. Baumgardner, J. Wroten, M. Mendillo, D. Hickey, B. Alford, R. Finnan Center for Space Physics - Boston University

2 BU Optical Network for Thermospheric Studies existing planned 1. Equatorial and low latitude Ionosphere (from magnetic equator to the crests of the Appleton Anomaly). ESF and MSTIDs, effects on trans-ionospheric radio signals using GPS and optical diagnosis. 2. Mid latitude Ionosphere (poleward from Anomaly crests to ~ 40 mag lat). Nighttime MSTIDs, E and F region coupling. 3. Sub-auroral Ionosphere (latitudes below auroral ovals). Stable auroral red (SAR) arcs (magnetic activity effects that transfer magnetospheric ring current energy into the I-T system)

3 Typical configuration of an imaging system Front lens (narrow, all-sky) Optical system (lenses, filters) Detector (CCD) 3

4 The typical airglow signatures in the thermosphere correspond to neutral O emissions at 6300 Å and 7774Å * 7774Å emission is caused by the radiative recombination of O + * O e O h 7774 * The so-called oxygen red line at 6300 Å (OI 6300 Å) represents the spontaneous de-excitation of atomic oxygen from the 1 D state to the 3 P ground state. O( 1 D) is produced mainly by two processes involving O +. The first one with O 2 and the second one, less important, with N O2 e (1 ) O O( D) 1 O O O O 2 2 4

5 A [ O ] [ N ] [ e ] A D d D *Emission limited to 250 and 300 km is proportional to [O + ] [e - ]. I ( Rayleighs) 10 dh * Combining intensities of these two emissions: max Tinsley, 1973; Makela et al, 2001 h I I

6 630.0 nm Airglow: ESF, MSTIDs and SAR arcs NASA, ISS From Baumgardner et al., 2013 ESF MSTIDs From Kelley et al., 2003

7 ESF structures El Leoncito (31 o S, -18 o mag) ~900 km Apex height ~ 1700 km Apex height Arecibo (16 o N, 23 o mag) ~1800km Apex height 7

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9 a. ESF depletions observed at both hemispheres 9

10 Proper comparison: map Arecibo structures to the Southern hemisphere MER unwarped ARE unwarped + mapped * Excellent correlation Longitudinal extent now similar at both sites * Depletions at MER not reaching the ARE conjugate point: not enough contrast? northward winds? 0028UT 0023UT 0135UT 0129UT 10

11 b. Speed * *

12 c. Intensity 3/10/15 11/29/14 * different background * Weaker B field * Thinner structures * Northward wind

13 1 June 2013 storm ESF effects at midlatitudes 40 deg magnetic latitude, L~ 1.7 (Martinis et al, 2015; Kil et al. 2016; Martinis et al., 2016)

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17 From Martinis et al., 2015

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19 Courtesy A. Coster

20 From Martinis et al., 2016

21 MSTIDs: Bands moving north(south)-westward in the southern(northern) hemisphere. Radially outward E fields Enhancements in airglow brightness related to TEC enhancements What about ΔTEC/min?: 0.3 TECU/min (for ESF ~ 1-2 TECU/min) 21

22 MSTIDs : Airglow changes; TEC changes; E-F region coupling -25 GPS data showing TEC variations All-sky images from El Leoncito, showing moving northwestward bright bands moving northwestward TEC maps courtesy of M. Nishioka

23 Climatology is relatively well understood: American and European sectors show peak activity in both solstices. Coupling between E and F regions and inter-hemispheric coupling play crucial roles. (from Martinis et al., 2011) (from Martinis et al., 2015) 23

24 E- F region coupling Initial distribution of Fe+ at 102km altitude. Two rods aligned NW-SE. Westward wind in the E region. F-region suitable for Perkins instability Haldoupis et al.,2003 Courtesy Tatsu Yokoyama

25 For non-typical MSTIDs observations: holes in Fe+ density, Bright-only bands are produced. Thus, depending on the structure of Es layers and F-region winds condition in terms of the Perkins instability, bright-bands are explained

26 MSTIDs: C/NOFS and ASIs

27 Feb :20 UT (5:05 UT) 6:50UT

28 (1)E* mer and E* zon fluctuations consistently in phase (2)V* mer and V* zon as well as B* mer and B* zon about 180 out of phase; (3)components of V* and B* varied out of phase with each other. Burke et al, 2016 explained phase offsets based on Alfven waves properties: 1- the B* and E* vectors lie in orthogonal planes. 2- If both components of E* have the same signs, B* components must have opposite polarities. B * E * Bˆ V B Am N V * */ 0 i p i A B0 B0 Thus the phase relationships between the measured components of E*, B* and V* are consistent with an Alfvén wave explanation. 0 S E* * ( * ˆ * ˆ) ( * ˆ * ˆ B E mer E zon B mer B zon ) o E * mer B * zon E * zon B * mer Bˆ (2) o o

29 W S ˆ 0.8 [ E * ( / ) * ( ) * ( / ) * ( )] 2 mer mv m B zon nt E zon mv m B mer nt B m Burke et al., 2016 S positive Energy flowing from the southern hemisphere

30 Feb

31 Stable auroral red (SAR) arcs BU Millstone Hill Aurora SAR arc USU/BAS Rothera(M. Taylor-T.Moffat) From Kozyra et al, 1997

32 1 June 2013 * Observation of SAR arcs in both hemispheres: *First conjugate ground-based detection of SAR arcs * Morphology not exactly the same; e.g., Rothera s SAR arc shows sharper poleward edges

33 SAR Arc positions on 1 June 2013 at: Millstone Hill Rothera

34 31 May-01 June 01 June 00 UT- 09 UT

35 North

36 Comparison with models BU airglow code to obtain Background brightness MSIS + IRI; TIEGCM;GITM To model SAR arc, need to incorporate a ring-current-ionosphere coupled model

37 Van Allen Probes to measure ring current ion populations All-sky images mapped into the equatorial plane

38 (a) (b) (b) HOPE and EMFSIS data for VAP B and A, The location of the plasmapause coincides with the increase in fluxes in the three ions between ~ 8:00UT and 08:20UT. VAP B is ahead and it samples field lines that connect the sub-auroral ionosphere where a SAR arc is being measured by the MH ASI located to the west

39 X ASIs images mapped into the geomagnetic equatorial plane at 13:00, 13:24 and 13:31 UT. The Sun is at the bottom and dusk to the left (viewed from the south pole). A SAR arc is observed close to L=3. The red X indicates the satellite location at the image time

40 We want to investigate how ring current properties could be related to SAR arc characteristics Time variations of H+ fluxes with initial energy peaking at 10 kev (top) and 40 kev (middle) in a background of thermal plasma (1 ev, density = 2000 cm -3 ). Rate of energy loss as a function of ion energy (bottom) (from Fok et al., 1993) Energy loss experienced by ring current ions traveling through: (a) thermal electron gas with temperature 5800K and density 1000 cm -3 (Kozyra et al., 1997); (Kozyra et al., 1993)

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42 03/07/ nm nm 70 W

43 Survey Operations Ion Velocity Meter pointed to ram, imaging instrument views to port. Operates in this configuration >90% of mission. Conjugate Operations Set of yaw maneuvers to provide winds at both magnetic footpoints Courtesy T. Immel)

44 Summary Network of all-sky imagers allows the study of ionospheric processes from low to sub-auroral latitudes Large Ni perturbations are not always present when airglow bands are observed (Plasma blobs and MSTIDs). Satellite measurements provide S values that can help to determine source region of MSTIDs First ground-based conjugate observations of SAR arcs indicates similar morphologies. Simultaneous VAP data can be used to quantify M-I coupling at subauroral latitudes. Presence of low energy ions might validate Coulomb collisions as the mechanism providing energy source of SAR arcs Ground-based support for ICON and GOLD

45 TEC waves- Otsuka et al, 2013 Kuhlunsburg 54 o geo lat Inclination = 69 o

46 300 km 75 ZA dashed circle 400 km 75 ZA solid circle