Type II CME Science Case
Eruptive activity in the solar atmosphere can result in the ejection of plasma at over 2000 km/s, known as a coronal mass ejection. CMEs often drive shock waves through the solar system which can cause intense radio emission (known as a type II) and the eventual detection of the shock at Earth by satellites in-situ. However, although shocks may be readily identified using both radio and in-situ data, few studies have been performed regarding the relationship between these observables.
By relating the radio and in-situ manifestations we may improve our understanding and forecasting of a shock wave impact at Earth.
- We initially query the wind typeii_soho_cme catalogue for shock radio burst parameters such as start time, end time and observed frequency.
- The time of the event is then passed to a query of the soho_lasco_cme catalogue, from which a number of CME parameters are chosen, including position angle, angular width, final velocity and velocity uncertainty. The time of the event is also passed to a component that queries the goes_sxr_flare catalogue and obtains the latitude, longitude and strength of the associated solar X-ray flare.
- This information parsed from the catalogues is then used to run a ballistic propagation model known as SHEBA to produce an ETA at Earth. The ETA of this second iteration is then compared to a catalogue of in-situ shocks and CME detections in order to confirm if there was any positive shock.
We analyse an eruptive event that occurred on 11 April 2004. The event was associated with a X-ray flare and a CME which was observed by the LASCO telescopes at 04:30 UT with central position angle 203_, angular width 314, and speed 1645 km s-1.
- During this time a type II radio burst was observed by WIND/WAVES at 04:20 UT. The associated CME is propagated forward using the SHEBA propagation model to find an initial ETA range of 2004/04/12 05:57:54 21:10:41 UT.
- We evaluate the solar wind speed at this time from the catalogue of the ACE spacecraft (which measures solar wind speed at Earth). We obtain a solar wind speed of 442 km s-1, which is used to re-evaluate the CME speed and then run SHEBA a second time. This is done to take into account the fact that CMEs are slowed down by a solar wind drag effect.
- The new ETA range is 2004/04/12 05:57 2004/04/15 03:47 UT . This range is then searched for a positive detection of a shock in-situ. A search for a shock detection by the SOHO CELIAS instrument reveals a positive shock detection at 2004/04/12 17:35 UT, within the expected time window.
With regard to our science case stated above, the workflow successfully related a radio and in-situ shock detection via a CME propagation model.
- "Metaworkflows and Workflow Interoperability for Heliophysics". Dr. Gabriele Pierantoni, Dr. Eoin Carley, International Workshop on Science Gateways (IWSG 2014), Dublin, June 2014