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4D ionisation dynamics during storms of the recent solar maximum

Cathryn Mitchell, Ping Yin, Paul Spencer and Dmitriy Pokhotelov,

University of Bath, UK

www.invertcsi.com

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Outline

Introduce the imaging method

Describe physical results

1. October 2003 - differences from a quiet day in terms of TEC

2. Uplifts in F-region plasma height – several storms

3. High latitude to polar cap imaging

What can the imaging do in its own? Where next?

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Imaging (MIDAS)

Imaging software uses mainly GPS data

Produces 3D time-evolving electron-density maps over a wide area

Resolution over North America and Europe is typically 15 minutes and tens to hundreds of km

Recent capability added to image continuously from mid-to-high latitudes across the polar cap ionosphere

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Ground-based GPS

Space-based GPS

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Vertical TEC

Electron density 2D Electron density 3D

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1. Comparison between a quiet day (23rd) and storm day (30th ) October 2003 in terms of TEC

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QUIET DAY

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STORM DAY

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QUIET DAY

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STORM DAY

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Storm day (30th ) October 2003 in terms of iso-contours of electron density

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Over the USA the quiet day and storm day are almost identical at 12 UT

Enhancement in TEC/density over South-East USA has started by 13 UT (just after sunrise)

Enhancement in TEC/density evolves into longitudinally limited structure

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2. Uplifts in the F-region at mid-latitudes

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15th July 2000

Europe (15 E) USA (70 W)

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F-region uplift characteristics for three storms  - July 2000, October 2003 and November 2003

• Dramatic elevation of the F-region over Europe and the USA

• All three storms show an east-west time delay in the peak height elevation: European sector, then east coast of the USA, then west coast of the USA

• The F-region elevations move from high latitudes to lower latitudes for the Nov 2003 storm but for the other two storms the elevation is simultaneous across all latitudes

The uplifts in the USA sector are always accompanied by increasing TEC/electron density but those in the European sector are accompanied by decreasing TEC/electron densities

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3. Imaging into the polar cap

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MIDAS – polar cap

Specific problems for imaging the polar-cap

• Limited ground-based data

• Severe gradients, localized features

• Fast moving structures

Incorporate Wiemer model of the convection to compensate for missing data

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MIDAS – mid and low latitude

Low resolution global image using spherical grid centred on geographic pole

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MIDAS – mid and high latitude

Acknowledgement: Wiemer electric field model

Spherical grid rotated equator and centred on geomagnetic pole

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MIDAS – mid and high latitude

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Electron density as a function of height and universal time from the EISCAT radar (69oN,19oE), above, and MIDAS below, 30th October 2003

MIDAS – comparison to EISCAT

Acknowledgement: EISCAT Scientific Association, in particular Ian McCrea at CCLRC

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Summary and questions

• Enhancement in TEC/density on 30th October 2003 starts just after sunrise and grows into a longitudinally limited feature – why?

• For three storms the uplifts in the F-region start in Europe and then appear in the USA about 1 hour later – why?

• Evidence that for similar local times (different storms) the uplift occurs during decreasing TEC in Europe but increasing TEC in USA – significant?

• Polar-cap imaging shows the polar cap plasma convecting but does not provide evidence of a continuous TOI from mid-latitudes into the polar cap

Future work

Can we reproduce the imaging results using a physical model?