prof. jøran moen - eiscat kick-off seminar . future perspectives ... patches (gdi - gradient drift...
TRANSCRIPT
Jøran Moen
Multiscale physics, ionosphere space
weather challenges for navigation and
communication
EISCAT_3D kick-off seminar
Future perspectives
• Multi-point: Mother + daughters
• Multi-scale : Ground + in-situ (MHD, ion, and electron scales)
Cross scale
mission/
SCOPE
We will develop 4D tools to study multi-scale processes in
space plasma
4DSpace Main Objective
“We study the generation processes of turbuelence and the role
of turbulence in the energy transfer from space down to the
Earth, and its implication for space weather.”
Require multi-scale studies : 4D = 3D Space + Time
Group: 4DSpace
Different aspects
common framework
Instruments
Data analysis
4D SPACE
in situ
studies
Mechanical
solutions
Theory and
simulation
Department of Physics
- Plasma and Space Science group
- Electronics group
- Technical staff
- Electronic Lab, Mechanical Workshop
Department of Mathematics
-Fluid dynamics group
-Mechanics group
Department of Informatics
-Nanoelectronics group
Space weather effects: Ionospheric irregularities degrade GPS
signal quality
Societal impacts: Variability in GPS position accuracy and
fall out of services
The user needs: Forecasts about POSITIONING
ACCURACY, signal INTEGRITY, and
service CONTINUITY.
We need a physics
description of the
underlying physics in order
to develop numerical
forecast models
GPS Space weather
forecasts
Figure: Polar dial plots show the occurrence rate of GPS scintillations
observed at Ny-Ålesund (σϕ from (a) [0.1, 0.25] rad og (c) ≥ 0.5 rad)
Jin et al., JGR, 2015
Day : 10%
of the time
Night
0.1%
of the time
GPS scintillations
Plasma instibilities – driven by plasma
gradients and flow shears
• Flow channels => shears (KHI)
• Patches => density gradients (GDI)
• Auroral precipitation=> ionization gradients
(GDI)
Moen et al., 2008 Foster et al., 2005
F-region Instability modes:
Two generic instability mechanisms
GRADIENT DRIFT INSTABILITY KELVIN HELMHOLTZ INSTABILITY
EARLY EARLY LATE LATE
ixe
Vx
n
nGDI
0
1From Basu et al. (1988; 1992)
Cusp ionospheric density gradients
and formation of backscatter
irregularities
NIMS
B
E
y
n
n0
1 5-10 min
Gradient drift instability
growth rate
Auroral
boundary
Moen et al., JGR 2002
Motivation for the ICI sounding rocket program
• GDI instability growth time ~10 minutes based on ground
based techniques. Too slow !! (Moen et al. 2002)
• Discrete cusp precipitation may give rise plasma
structuring (Kelly et al., Moen et al., 2002)
Conclusion in 2002 : High resolution in-situ observations
are needed to test and quantify plasma instability modes!
“A space weather rocket program”
The Investigation of Cusp Irregularities
(ICI) Rocket Program
Payload :
Length: 2.9 meter
Weight : 140 kg
Apogee : ~350 km
Flight time : 10 min
ICI-4 instrumentation
FBP : Fixed Bias Langmuir Probe – ISAS/JAXA m-NLP : multi –Needle Langmuir Probe system – UiO LEP-ESA : Low Energy Particle spectrometer (10eV-10keV),
ISAS/JAXA EFW : Electric Field and Wave Experiment, UiO ADM : AC/DC Magnetometer – LPP, Ecole Polytechnique,
France.
FGM : Flux Gate Magnetometer Univ. of Alberta, Canada
SRADS: Sounding Rocket Attitude Detection System, UiO
UiO’s m-NLP system : Multiple Needle
Langmuir Probes
Absolute electron density measurements
5-10 kHz sampling rate : meter –scale
resolution
v
i2
Miniaturization is Key for us
V
IKNe
22
Bekkeng et al., Meas. Sci. Technol., 2010
Jacobsen et al. Meas. Sci. Technol., 2010
Two generic mechanisms for to polar cap scintillations:
i) Flow shears (KHI – Kelvin Helmholtz Instability)
ii) Patches (GDI - Gradient Drift Instability)
ICI-2
GDI -electron clouds
ICI-3
KHI –flow shears
ICI-4
Auroral
blobs
F-region electron density
along the trajectory
Is modulated by the cusp
electron precipitation
ixV
ICI-2 main results:
GDI-TEST POSITIVE
UNSTABLE:
STABLE :
Gowth rate: ~10’s of
seconds.
Ne
eNixV
eN
ie VN
||
ie VN
||
STABLE UNSTABLE
Moen et al., GRL, 2012
ICI 2&3 - Summary
KHI and GDI growth times may both be ~1
minute on spatial scales >1 km.
The GDI dominates for spatial scales <1 km.
GDI in cusp may be initialized by cusp
electron beams (~100 eV)!
April 20th 2012 4-NLP status
Double spectra ambiguity:
There is a need for 3D measurements
Turbulence: The long wavelength regime is due to an MHD instability and the
steepening may be due to drift waves or to diffusion (LaBelle et al., 1986; Kelley,
2009).
Or Steeping of waves: the spectral indices are related to the amplitude of the
structures and the steepening of waves (Hysell et al., 1994).
ICI-2 Kinetic
The worst GNSS space weather phenomenon in the Scandinavian Arctic
Sector occurs when polar cap patches that have moved from the Daytime
US across the polar cap enter our Night-time auroral oval (then termed
Auroral blobs) (Jin et al., SWSC, 2014) Jin, Y., J. I. Moen, and W. J. Miloch (2014), GPS scintillation effects associated with polar cap patches and
substorm auroral activity: direct comparison, J Space Weather Spac, 4(A23), doi:10.1051/swsc/2014019.
Polar cap patches
GNSS σφ + All-sky aurora + airglow patches
Jin et al. (2016), JGR-Space,. doi: 10.1002/2016JA022613