1. Space weather challenges of the polar cap ionosphereby
J. Moen, K. Oksavik, L. Alfonsi, Y. Daabakk, V. Romano, and L. Spogli
ESWW9 : 09 NOV 2012

2. Contributions to COST ES0803
Contents:
Polar Cap Space Weather
GNSS user needs
Scintillation climatology
F-layer Instability modes (GDI-KHI)
ICI-rocket results
Patch - tracking
Summary

4. Polar cap “electron clouds” during the Halloween Storm
Courtesy of Un. of Bath 4

5. Societal impacts:

6. HOWEVER…… Scintillation Climatology Maps:
Disturbed days
Quiet days
Foster et al. JGR 2005
Courtesy Spogli et al., EGU 2009
General view : The climatology maps are found consistent with the ExB drift/Gradient Drift Instability on polar cap patches
Spogli et al., Ann. Geophys, 2009 & Prikryl et al., Ann. Geophys. , 2010
HOWEVER…… 6

7. F-region Instability modes:
Two generic instability mechanisms
F-region Instability modes:
KELVIN HELMHOLTZ INSTABILITY
GRADIENT DRIFT INSTABILITY
EARLY
LATE
EARLY
LATE
HYBRID MODES:
KHI + GDI (Carlson et al., 2007)
Particle precipitation + GDI
RFE
Has to be VERYFIED by In-Situ Measurements

8. GNSS user needs – Aviation and Offshore –complex operations
Scintillation forecasts
Signal integrity
Position accuracy
Service continuity
Forecast and mitigation techniques pending on a proper physical description of turbulent ionospheric regions
In-situ investigations needed!
Signal emitted
Scintillations
at the receiver

9. ICI 2 : 5DEC2008 ICI 3 : 3DEC2011 ICI 4 : 2013 Winter
INVESTIGATION OF CUSP IREGULARITIES ROCKET PROGRAM
ICI 2 : 5DEC2008
ICI 3 : 3DEC2011
ICI 4 : 2013 Winter
All rockets from Svalbard!
10m
1s data

11. ICI 2 Encounter of HF back-scatter
First measurements of Decameter scale plasma structures associated with HF backscatter targets

12. ICI-2 major objective: Test the Gradient Drift Instability (GDI)
STABLE
UNSTABLE
Instability growth rate

13. Gowth rate: ~10’s of seconds.
F-region electron density along the trajectory
Is modulated by the cusp electron precipitation
STABLE
UNSTABLE
GDI-TEST POSITIVE
UNSTABLE:
STABLE :
Gowth rate: ~10’s of seconds.

14. σφ≥0.25
S4 ≥ 0.25
Phase scintillation dominates
Phase scintillation in cusp for Bz north indicates that instabilities are related to electron precipitation

15. Rate of TEC changes (ROT)
Bz>0
Bz<0
ROT
ROT_SD
Large ROT_SD values are associated with the presence of multi-scale structures

16. FLOW CHANNEL EVENTS: Kelvin-Helmholtz Instability (KHI)
Reversed Flow Events (RFE), life time of min.
A candiate for two-step KHI-GDI
GDI growth time 1-3 min
To be verified in-situ: ICI-3 rocket data being analyzed

17. Map and track model for polar cap patch motion
The model is based on SuperDARN convection patterns (Ruohoniemi and Greenwald 1996; Ruohoniemi and Baker 1998)
Promising tool for 1-2 hours forecasts the movement of turbulent electron clouds/scintillation regions

18. SUMMARY:
We have demonstrated evidence for rapid GDI growth on km scale cusp precipitation gradients (10’s of seconds).
We have determined the KHI growth rates for Reversed Event Flow events (1-3 minutes). Possible candidate for the KHI-GDI two step mechanism
Large ROT_SD indicates that the multi-scale structure of polar cap patches is maintained during their transit from day to night
We have prototyped a tool for mapping and forward trajectory prediction of polar cap patches that allows for 1-2 hours precise scintillation forecasts.