University of Bath 4D ionisation dynamics during storms of the recent solar maximum Cathryn Mitchell, Ping Yin, Paul Spencer and Dmitriy Pokhotelov, University of Bath, UK

University of Bath Outline Introduce the imaging method Describe physical results 1. October 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?

University of Bath 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

University of Bath Ground-based GPS Space-based GPS

University of Bath Vertical TEC Electron density 2D Electron density 3D

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

University of Bath QUIET DAY

University of Bath STORM DAY

University of Bath QUIET DAY

University of Bath STORM DAY

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

University of Bath

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

University of Bath 2. Uplifts in the F-region at mid-latitudes

University of Bath 15 th July 2000 Europe (15 E)USA (70 W)

University of Bath 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

University of Bath 3. Imaging into the polar cap

University of Bath 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

University of Bath MIDAS – mid and low latitude Low resolution global image using spherical grid centred on geographic pole

University of Bath MIDAS – mid and high latitude Acknowledgement: Wiemer electric field model Spherical grid rotated equator and centred on geomagnetic pole

University of Bath

MIDAS – mid and high latitude

University of Bath Electron density as a function of height and universal time from the EISCAT radar (69 o N,19 o E), above, and MIDAS below, 30 th October 2003 MIDAS – comparison to EISCAT Acknowledgement: EISCAT Scientific Association, in particular Ian McCrea at CCLRC

University of Bath Summary and questions Enhancement in TEC/density on 30 th 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?