1. November 2004 Storms – Australian experiences By Phil Wilkinson, Garth Patterson and Patrick Phelan IPS Radio and Space Services Dept Industry, Tourism and Resources P O Box 1386, Haymarket NSW 1240 AUSTRALIA

2. November 2004 Storm - Solar Forecasts –HF warnings for fadeouts were current Region development meant there was always a potential for a major flare. Alerts –Proton alert issued 7 Nov, and the PCA continued until 13 Nov. Effects –M class flares Nov 3, 6 (with partial halo CME); X2 class flares Nov 7 (full halo, Type II/IV), 10 (Type II/IV). –Fadeouts occurred, but were not severe –PCA prevented HF equipment working in Antarctica –HF absorption observed at Hobart late afternoon 8 th November Coincident with northern hemisphere auroral sightings

3. November 2004 Storm – Mag-1 Forecasts –Geomagnetic warnings current for period. –Initial (Nov 8) severity of storm not anticipated, Ap = 60 expected, Ap = 189 observed. –Forecast based on M class flares Nov 5/6, plus weak halo CME –Was this the source of the disturbance on Nov 8? –Subsequent (Nov 10) storm expected, but severity under-estimated X2 on 7 th Nov expected to contribute further activity –Was this the source of renewed activity 10-11 Nov –and mid-latitude aurora? –and later development (Nov 11-12) over-estimated, X2/3B flare considered a potential risk for increased activity –Parallel ribbon flare; Castell U, 3B for both Learmonth and Culgoora, all suggested this cold produce a major geophysical event, BUT IT DIDN’T. –Was the SI on 11 th related to this event? The associated Bz > 0. Alerts –Several auroral alerts issued (7 – 11 Nov, 2004), some to low latitudes (10 Nov). –Geomagnetic sudden impulses (SI) (Nov 7, 1 SI & Nov 9, 2 SI. Nov 11 1 SI) detected and alerts issued automatically.

4. November 2004 Storm – Mag-2 Effects –Large positive and negative bays observed across Australia At low latitudes these caused significant currents to flow in gas pipelines (being investigated). Saturated IPS PC variometer array –Auroral sightings (23 email messages) across much of southern Australia, Europe (1) and northern USA Nov 7, 09 – 11 UT, Sidings Springs and Western Australia, Europe, USA. Nov 10, 08 – 1230 UT, Bathurst, Dunedin, Hobart. Several pictures were provided –A collection of southern aurora pictures can be found at http://homepage.mac.com/stevoss/Menu8.html

5. November 2004 Storm – Mag - 3

6. November 2004 Storm – Mag - 4 Aurora – Siding Springs Observatory, NSW, 8 th November (0950 - 1030 UT) Credit: Gordon Garradd (http://members.ozemail.com.au/~loomberah)

7. November 2004 Storm – Mag - 5 Aurora – Bathurst, NSW – observed for 10 minutes, 10 th November (1047 – 1057 UT) Credit: Ray Pickard, Bathurst Observatory (http://www.bathurstobservatory.com.au)

8. November 2004 Storm – Solar wind-1 Alerts –Solar wind shocks and geomagnetic Sudden Impulses are automatically detected and alerts issued. –Solar wind shocks (7 Nov, 3 shocks; Nov 9, 2 shocks), –and geomagnetic sudden impulses (SI) (Nov 7, 1 SI & Nov 9, 2 SI. Nov 11 1 SI). All events detected automatically and alerts issued.

9. November 2004 Storm – Solar wind-2 Solar wind Interplanetary Field: November 3 – 14, 2004 Source: SEC (composite image) http://www.sec.noaa.gov/Data/solar.html

10. November 2004 Storm – Solar wind-3 Solar wind particle fluxes: November 3 – 14, 2004 Source: SEC (composite image) http://www.sec.noaa.gov/Data/solar.html

11. November 2004 Storm – Ionosphere - 1 Forecasts –HF warnings current for storm period, –Duration of storm not correct Allowing for possible increased activity Effects –Maximum Useable Frequencies (MUF) depressed 7 Nov. Due to large height rises rather than depressed peak densities. –Greater ionospheric variability Than usually experienced during large storms Large ionisation gradients across Australia –Hemispheric differences Southern (summer) hemisphere affected more than northern (winter) hemisphere (note indices).

12. November 2004 Storm – Ionosphere - 2

13. November 2004 Storm – Ionosphere - 3

14. November 2004 Storm – Ionosphere - 4

15. November 2004 Storm – Media - 1 Press release –Prepared for release Nov 8, released Nov 9 Delay unavoidable, but ultimately useful Considerable interest, especially the prospect of observing aurora Press –Coverage in local newspapers, including auroral pictures from event Also on some media websites Radio –Featured on prime news bulletins and drive time TV –One TV interview used.

16. November 2004 Storm – Media - 2 Aurora – observed Thursday 11 th November, near Hobart Credit: Hobart mercury, November 11 th or 12 th, 2004

17. November 2004 Storm – Timeline

18. November 2004 Storm – Summary Forecasts: –Warnings for fadeouts and geomagnetic activity were current for the storm period –Severity of storm was not correctly forecast –Duration of geomagnetic and ionospheric storm not correctly forecast Partly because a third storm, predicted for 11 th November, did not eventuate. Alerts: –Auroral alerts for the period were reasonably helpful for observers (see timeline) Effects: –Australasian ionosphere severely disturbed Major gradients and significantly increased spatial variability –Severe geomagnetic disturbances observed Caused extreme current flows in low latitude gas pipeline –Aurora Wide observations of active displays –Media Good media interest, especially in the potential for auroral observations