Jøran Moen University of Oslo Also at The University Centre in Svalbard

Transcription

1 The ICI series of Space Weather Rockets Jøran Moen University of Oslo Also at The University Centre in Svalbard

2 GPS ERROR SOURCES Courtesy of Alfonsi

3 IONOSPHERIC EFFECTS ON GPS SIGNALS L-band scintillations Ionospheric irregularities can produce short term phase and amplitude fluctuations in the carrier of the radio waves which pass through them. These effects are commonly called Amplitude and Phase Ionospheric Scintillations. Signal emitted by satellite Severe amplitude fading and strong phase scintillation affect the reliability of GPS navigational systems and satellite communications. Scintillations at the receiver The scintillations occur mainly at polar, auroral and equatorial regions; more frequently around the solar maxima Courtesy of Alfonsi

4 The perturbed high latitude ionosphere Courtesy of Un. of Bath

5 Experimental observations can improve our understanding of the cause-effect mechanisms producing negative effects on GPS signals Courtesy of Un. of Bath Synergic adoption of tomographic technique and scintillations measurements De Franceschi et al., 2008

6 On the ICI-series of sounding rockets ( ) ICI-2 launch 10:35 UT 5 Dec 2008 Photo: Martin Langteigen

7 The observational relationship between the optical cusp and HF radar cusp is well documented.!! However, we are lacking verification on how HF backscatter irregularities es form!! Spectral widths 220 ms -1 Moen et al., Ann. Geophysicae, 2000

8 Oi Original i lscience Objective: We want to test the potential role of gradient drift instability to generate decameter scale HF backscatter targets. Auroral boundary NIMS Gradient drift instability growth rate γ = 1 n 0 Δn E Δ y B 3-10 min

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10 Background I: Langmuir Probe A typical I-V characteristic of a Langmuir probe. (from Lebreton et al., 2006) OPERATIONAL MODES: Swept probe : Advantage: N i, N e, T e at a time resolution of ~1s Disadvantage: 7 km spatial resolution at 700 km altitude Fixed Bias: Advantage: khz sampling rate and high spatial resolution Disadvantage: I e is a function of (N e e, T e e) ). Cannot make absolute density measurements by one probe

11 Background II: Langmuir Probe Debye length: λ = D ε 0 kt e / ne 2 λ D in the ionosphere is of the order of cm r If r λ D Sheath effects are important. If r << λ D Sheath effects can be neglected Smaller the better! But we need to collect a sufficiently large current to measure!

12 m-nlp : Multi-Needle Langmuir Probe 2 or more cylindric probes: r = 0.25 mm, l = 25 mm Advantages: Shielding effects can be neglected khz sampling rates allow high spatial resolution The need for T e can be eliminated

13 Elimination of T e I = K AN T 1+ e 1 e e I K VT 2 1 e ( ) 2 K AN T ( K AN ) K V 2 = + e 1 e e 1 e 2 2 ( ) 2 K AN K ΔV ΔI = e 1 e 2 N 2 e = K 3 ΔI 2 Δ V We don t even need to know the space craft potential!

14 2 N e = K 3 2 ΔI ΔVV

15 ESTEC Laboratory Test : It works!

16 INSTRUMENTATION on ICI-3 FBP : Fixed Bias Langmuir Probe ISAS/JAXA m-nslp : multi -Needle&Sphere Langmuir Probe system University of Oslo LEP-ESA : Low Energy Particle spectrometer (10eV-10keV), ISAS/JAXA EFW : Electric Field and Wave Experiment, University of Oslo. ADM : AC/DC C Magnetometer ete - LPP. SRADS: Sounding Rocket Attitude Detection System (UiO)

17 PMAF

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19 HF1

20 HF2

21 HF3

22 HF1 HF2 HF3 K K K A A A W W W

23 HF1

24 HF2 HF3

25 UNIVERSITY OF OSLO Tentative schedule: ICI Winter ICI Winter ICI Winter (Solar Max?) ICI Summer/Equinox All rockets from Svalbard! Research Section for Plasma and Space Physics

26 EISCAT VALBARD RADAR : SP-NO-FASM Reversed flow events: A new category of flow channels opposing the large-scale background flow: First discovered by ESR Associated with strong flow shears which may turn upside down the way we think about ionospheric instabilities And generation of HF backscatter irregularities.

27 ICI-3 objectives: Our main objective is to obtain a better physical description of instabilities and wave phenomena driven by the newly discovered Reversed Flow Events (RFEs) in the winter cusp ionosphere. Test whether the RFEs are associated with a tangential ti discontinuity (frozen into plasma) or a rotational discontinuity (indicative of reconnection). Test whether the RFE-Birkeland current sheets are related to inverted Vs. Identification of wave phenomena and non-linear saturation.