heliophysics - User contributions [en]

07/23/2012 23:00:00 UTC

2014-10-10T16:57:56Z

Temmer isest:

This was the famous energetic, very fast event directed at STEREO-A. There were two consecutive prominence eruption/flares starting about 02:20 UT on July 23, seen best in SOHO and STEREO-B observations. The shock hit STEREO-A on July 23, 20:55 UT, followed by two ICMEs, the first starting about 23:00 UT and the second at 01:51 UT on July 24.

- N. Nitta says “It was not an Earth-affecting event, but it was said to have possibly been as geoeffective as the Carrington event had it occurred 9 days earlier [and been aimed at Earth-DW]. I think it is important to understand the interplanetary conditions as disturbed by AR 11520 over an extended period.”

- M. Temmer: “i am currently working together with Nariaki on the complex (two-step) eruption from July 23, 2012 event aiming to simulate the short arrival time and high impact speed by using the analytical drag-based-model. the low density in interplanetary space as well as the high mass of the CME might be the decisive factors for this event to be so fast. The question remains whether the event from July 19 is able to lower the density over several days and as such is able to change the interplanetary conditions. i had during the process of the analysis nice discussions with Ying Liu and Janet Luhmann. We would like to encourage people to take a closer look on this event. We had subjective interpretations of the white-light structures, but most important found no conclusion on the high magnetic field as measured in-situ for both magnetic structures. Is it maybe something intrinsic to the active region? … it would be good to get modelers involved for gaining some deeper insight into the complex eruption process and its in-situ effects.”

[Added by D. Webb]

- M. Temmer: A key element for the extreme character of the July 23, 2012 eruption is a high level of flare energy release over a long time range (max acceleration 2.2km/s^2, ~30 minutes of acceleration phase). Due to an efficient magnetic reconnection process the CME might reach a very high speed (max v=2580+/-280km/s derived from GCS 3D model) that is sustained by the prolonged energy release. The underlying mechanism which is able to build up the energy in the source region as well its conversion into such high kinetic energy is beyond the limit of information from observational data. We encourage modelers to provide further insight into the physics of source regions and reconnection processes related to such extreme events. The very high mass of the CME (1.5x10^16 g) as well as the reduced solar wind density in IP space (1-2/cm^3) due to A) the prior CME from July 19, 2012, B) general low density owing to the low solar activity, may have been the decisive factors for making this event super-fast. In addition, the largely radial orientation of the interplanetary magnetic field, due to its stretching by the CME from July 19, may have reduced the pile-up of solar wind and delayed its replenishment. [Temmer and Nitta, Solar Physics, under review]

REFERENCES:
Russell, C. et al., ApJ, 770, 38, 2013; Ngwira, C. et al., GRL, 2013; Baker, D., Space Weather, 11, 585, 2013; Liu, D.L. et al., Nature Comm., 5, 4381, 2014.

07/23/2012 23:00:00 UTC

2014-10-10T15:21:17Z

Temmer isest:

This was the famous energetic, very fast event directed at STEREO-A. There were two consecutive prominence eruption/flares starting about 02:20 UT on July 23, seen best in SOHO and STEREO-B observations. The shock hit STEREO-A on July 23, 20:55 UT, followed by two ICMEs, the first starting about 23:00 UT and the second at 01:51 UT on July 24.

- N. Nitta says “It was not an Earth-affecting event, but it was said to have possibly been as geoeffective as the Carrington event had it occurred 9 days earlier [and been aimed at Earth-DW]. I think it is important to understand the interplanetary conditions as disturbed by AR 11520 over an extended period.”

- M. Temmer: “i am currently working together with Nariaki on the complex (two-step) eruption from July 23, 2012 event aiming to simulate the short arrival time and high impact speed by using the analytical drag-based-model. the low density in interplanetary space as well as the high mass of the CME might be the decisive factors for this event to be so fast. The question remains whether the event from July 19 is able to lower the density over several days and as such is able to change the interplanetary conditions. i had during the process of the analysis nice discussions with Ying Liu and Janet Luhmann. We would like to encourage people to take a closer look on this event. We had subjective interpretations of the white-light structures, but most important found no conclusion on the high magnetic field as measured in-situ for both magnetic structures. Is it maybe something intrinsic to the active region? … it would be good to get modelers involved for gaining some deeper insight into the complex eruption process and its in-situ effects.”

[Added by D. Webb]

- M. Temmer: A key element for the extreme character of the July 23, 2012 eruption is a high level of flare energy release over a long time range (max acceleration 2.2km/s^2, ~30 minutes of acceleration phase). Due to an efficient magnetic reconnection process the CME might reach a very high speed (max v=2580+/-280km/s derived from GCS 3D model) that is sustained by the prolonged energy release. The underlying mechanism which is able to build up the energy in the source region as well its conversion into such high kinetic energy is beyond the limit of information from observational data. We encourage modelers to provide further insight into the physics of source regions and reconnection processes related to such extreme events. The very high mass of the CME (1x10^16 g) as well as the reduced solar wind density in IP space (1-2/cm^3) due to A) the prior CME from July 19, 2012, B) general low density owing to the low solar activity, may have been the decisive factors for making this event super-fast. In addition, the largely radial orientation of the interplanetary magnetic field, due to its stretching by the CME from July 19, may have reduced the pile-up of solar wind and delayed its replenishment. [Temmer and Nitta, Solar Physics, under review]

REFERENCES:
Russell, C. et al., ApJ, 770, 38, 2013; Ngwira, C. et al., GRL, 2013; Baker, D., Space Weather, 11, 585, 2013; Liu, D.L. et al., Nature Comm., 5, 4381, 2014.

07/23/2012 23:00:00 UTC

2014-10-10T15:20:25Z

Temmer isest:

This was the famous energetic, very fast event directed at STEREO-A. There were two consecutive prominence eruption/flares starting about 02:20 UT on July 23, seen best in SOHO and STEREO-B observations. The shock hit STEREO-A on July 23, 20:55 UT, followed by two ICMEs, the first starting about 23:00 UT and the second at 01:51 UT on July 24.

- N. Nitta says “It was not an Earth-affecting event, but it was said to have possibly been as geoeffective as the Carrington event had it occurred 9 days earlier [and been aimed at Earth-DW]. I think it is important to understand the interplanetary conditions as disturbed by AR 11520 over an extended period.”

- M. Temmer: “i am currently working together with Nariaki on the complex (two-step) eruption from July 23, 2012 event aiming to simulate the short arrival time and high impact speed by using the analytical drag-based-model. the low density in interplanetary space as well as the high mass of the CME might be the decisive factors for this event to be so fast. The question remains whether the event from July 19 is able to lower the density over several days and as such is able to change the interplanetary conditions. i had during the process of the analysis nice discussions with Ying Liu and Janet Luhmann. We would like to encourage people to take a closer look on this event. We had subjective interpretations of the white-light structures, but most important found no conclusion on the high magnetic field as measured in-situ for both magnetic structures. Is it maybe something intrinsic to the active region? … it would be good to get modelers involved for gaining some deeper insight into the complex eruption process and its in-situ effects.”

[Added by D. Webb]

- M. Temmer: A key element for the extreme character of the July 23, 2012 eruption is a high level of flare energy release over a long time range (max acceleration 2.2km/s^2, ~30 minutes of acceleration phase). Due to an efficient magnetic reconnection process the CME might reach a very high speed (max v=2580+/-280km/s derived from GCS 3D model) that is sustained by the prolonged energy release. The underlying mechanism which is able to build up the energy in the source region as well its conversion into such high kinetic energy is beyond the limit of information from observational data. We encourage modelers to provide further insight into the physics of source regions and reconnection processes related to such extreme events. The very high mass of the CME (1x10^16 g) as well as the reduced solar wind density in IP space (1-2/cm^3) due to a) the prior CME from July 19, 2012, b) low solar activity in general, may have been the decisive factors for making this event super-fast. In addition, the largely radial orientation of the interplanetary magnetic field, due to its stretching by the CME from July 19, may have reduced the pile-up of solar wind and delayed its replenishment. [Temmer and Nitta, Solar Physics, under review]

REFERENCES:
Russell, C. et al., ApJ, 770, 38, 2013; Ngwira, C. et al., GRL, 2013; Baker, D., Space Weather, 11, 585, 2013; Liu, D.L. et al., Nature Comm., 5, 4381, 2014.

07/23/2012 23:00:00 UTC

2014-10-10T15:19:26Z

Temmer isest:

This was the famous energetic, very fast event directed at STEREO-A. There were two consecutive prominence eruption/flares starting about 02:20 UT on July 23, seen best in SOHO and STEREO-B observations. The shock hit STEREO-A on July 23, 20:55 UT, followed by two ICMEs, the first starting about 23:00 UT and the second at 01:51 UT on July 24.

- N. Nitta says “It was not an Earth-affecting event, but it was said to have possibly been as geoeffective as the Carrington event had it occurred 9 days earlier [and been aimed at Earth-DW]. I think it is important to understand the interplanetary conditions as disturbed by AR 11520 over an extended period.”

- M. Temmer: “i am currently working together with Nariaki on the complex (two-step) eruption from July 23, 2012 event aiming to simulate the short arrival time and high impact speed by using the analytical drag-based-model. the low density in interplanetary space as well as the high mass of the CME might be the decisive factors for this event to be so fast. The question remains whether the event from July 19 is able to lower the density over several days and as such is able to change the interplanetary conditions. i had during the process of the analysis nice discussions with Ying Liu and Janet Luhmann. We would like to encourage people to take a closer look on this event. We had subjective interpretations of the white-light structures, but most important found no conclusion on the high magnetic field as measured in-situ for both magnetic structures. Is it maybe something intrinsic to the active region? … it would be good to get modelers involved for gaining some deeper insight into the complex eruption process and its in-situ effects.”

[Added by D. Webb]

- M. Temmer: A key element for the extreme character of the July 23, 2012 eruption is a high level of flare energy release over a long time range (max acceleration 2.2km/s^2, ~30 minutes of acceleration phase). Due to an efficient magnetic reconnection process the CME might reach a very high speed (max v=2580+/-280km/s derived from GCS 3D model) that is sustained by the prolonged energy release. The underlying mechanism which is able to build up the energy in the source region as well its conversion into such high kinetic energy is beyond the limit of information from observational data. We encourage modelers to provide further insight into the physics of source regions and reconnection processes related to such extreme events. The very high mass of the CME (1x10^16 g) as well as the reduced solar wind density in IP space due to a) the prior CME from July 19, 2012, b) low solar activity in general, may have been the decisive factors for making this event super-fast. In addition, the largely radial orientation of the interplanetary magnetic field, due to its stretching by the CME from July 19, may have reduced the pile-up of solar wind and delayed its replenishment. [Temmer and Nitta, Solar Physics, under review]

REFERENCES:
Russell, C. et al., ApJ, 770, 38, 2013; Ngwira, C. et al., GRL, 2013; Baker, D., Space Weather, 11, 585, 2013; Liu, D.L. et al., Nature Comm., 5, 4381, 2014.

Working Group 4

2014-10-08T06:25:54Z

Temmer isest: /* Preliminary list of events */

Campaign Event Group led by Nariaki Nitta (USA), Luciano Rodriguez (Belgium); At-large leaders: David Webb (USA)

A brief summary of the activity of WG4 at the workshop can be found [http://solar.gmu.edu/wiki/presentations/WG4_Summary_20130620.pdf here]. <br>

==Objectives==

*Provide textbook-style standard CME-ICME chain events from the Sun to the Earth based on the state-of-the-art observations and successful theoretical analysis and numerical simulation: happy stories

*Examine controversial Earth-Affecting CME/ICME pairs during the STEREO era (from 2007): surprising stories

*To analyse the complications that arise when linking CMEs to ICMEs

*To obtain new insights that could be applied when forecasting ICME arrivals at the Earth

*Integrate theory, simulations and observations in order to get a complete view of the chain of events from the Sun to the Earth

==Scientific Questions, Technique Approach/Methodology==

===What are the common issues when linking ICMEs to CMEs?===

*Multiple events

*Stealth CMEs

*CME deflection

*etc.

===Calculating arrival times===

*Projected vs 3D speeds

*Propagation models (DBM, ENLIL, etc.)

*Error margins

===When/why will a full halo CME not arrive to the Earth?===

===When/why will a narrow CME (as seen from L1) arrive to the Earth?===

===What solar parameters can we use to provide an estimation of geoeffectivity?===

===More interesting topics:===
*Forbush decreases (Mateja, Dragan, Darije)
*Sympathetic flares (Nariaki)
*SEPs (Bernd?)
*Prominence material in ICMEs, signatures in compositional data (Luciano)
*Determination of S/C path through the ICME, central or flank crossings
*Use of remote data to infer Bz: magnetograms, extrapolations, flux rope orientation
*False alarms: CMEs that did not arrive to the Earth when they were expected to, and viceversa.

==Preliminary list of events==

*3 April 2010

*1-4 August 2010

*14-15 February 2011

*12 July 2012

*23 July 2012

*28 September 2012

*5-9 October 2012

*6 February 2013

*12-17 March 2013

*11-14 April, 2013

*31 May 2013

*7 June 2013

*MiniMAx24 list (https://igam07ws.uni-graz.at/mediawiki/index.php?title=Main_Page:Event_Studies)

*WG1 events

==Selected campaign events==

*Textbook example: [http://solar.gmu.edu/heliophysics/index.php/07/14/2012_17:00:00_UTC 12 July 2012]

*Problematic event: [http://solar.gmu.edu/heliophysics/index.php/10/08/2012_05:00:00_UTC 5 October 2012] (stealth CME, ICME trailed by a HSS)

*Backup problematic event: June 7 2013 (MC a bit weak)

==Future Plan==
* Collect results of simulations and models
* Compare and integrate simulations results with observations
* Start/continue the work related to the scientific questions