05/31/2013 15:30:00 UTC - Revision history

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Davidwebb at 20:27, 29 September 2014

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	=References=		=References=
		+	*Gopalswamy, N., Tsurutani, B., Yan, Y.: 2015, Short-term variability of the Sun-Earth system: An overview of progress made during the CAWSES-II period, Progress in Earth and Planetary Sci., 2, 13, DOI 10.1186/s40645-015-0043-8
		+	*Nitta, N. V., T. Mulligan: 2017, Earth-Affecting Coronal Mass Ejections Without Obvious Low Coronal Signatures, Solar Phys., submitted.
		+	*Marubashi, K., K.-S. Cho, H. Ishibashi: 2017, Interplanetary Magnetic Flux Rope as Agent Connecting Solar Eruptions and Geomagnetic Activities, Solar Phys., submitted.
		+	*Webb, D, N. Nitta: 2017, Study on Understanding Problem Forecasts of ISEST Campaign Flare-CME Events, Solar Phys., submitted.

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 =Comment Section=
-*This is a varSITI campaign event
+*This is a varSITI campaign event for ISEST and ROSMIC.
 * M. Temmer >> question: CME? or rather CIR which caused the intense geomagnetic storm of -125 nT?

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 * M. Temmer >> question: CME? or rather CIR which caused the intense geomagnetic storm of -125 nT?
-I out together some discussion extracted from the email conversation during June 2 to June 6, 2013. If you were not involved and would be interested in receiving the original emails let me know and I will forward them...
+I put together some discussion extracted from the email conversation during June 2 to June 6, 2013. If you were not involved and would be interested in receiving the original emails let me know and I will forward them...
 Jie Zhang: I believe that the slow/gradual May 27 CME is the cause of the intense geomagnetic storm. The CME in LASCO is not even close to a typical halo CME (JAVA movie in SEEDS: http://spaceweather.gmu.edu/seeds/dailymkmovie_ql.php?cme=20130527 ). The extremely faint arm across the equator at a later time indicates a partial halo nature. But as pointed out by Nariaki, it would have been regarded as a backside event, due to the lack of surface signature.

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	Ian Richardson: I tend to agree with Volker that this is a classic CIR with what looks like forward (5/31~18 UT) and reverse (6/2~02 UT) shocks (or developing shocks; I haven't looked at any high resolution data), and evidence of a stream interface (e.g., the increase in speed, temperature, decrease in density at 6/1~08 UT) within the CIR , preceded by the already noted sector boundary. The slow-fast stream speed difference is quite large ~300-800 km/s, so this may account for the well formed CIR. Here is a schematic of a CIR after Belcher and Davis 1971, with additions [http://www.uni-graz.at/~temmerma/download/varsiti/2013May31_Ian.png]. [...]		Ian Richardson: I tend to agree with Volker that this is a classic CIR with what looks like forward (5/31~18 UT) and reverse (6/2~02 UT) shocks (or developing shocks; I haven't looked at any high resolution data), and evidence of a stream interface (e.g., the increase in speed, temperature, decrease in density at 6/1~08 UT) within the CIR , preceded by the already noted sector boundary. The slow-fast stream speed difference is quite large ~300-800 km/s, so this may account for the well formed CIR. Here is a schematic of a CIR after Belcher and Davis 1971, with additions [http://www.uni-graz.at/~temmerma/download/varsiti/2013May31_Ian.png]. [...]
		+
		+	Angelos Vourlidas: I’ve been trying to locate the source region of the CME on May 27th since Jie and Nariaki started discussing this. It is actually a polar CME (only occurring during polarity reversal periods) of streamer-blowout type with a considerable extent towards the ecliptic. Very faint. This event is Earth-directed and there’s some evidence in the in-situ data of multiple fronts encountering Earth between May 30-June 1st. The same can be seen in HI1-A images.
		+
		+	So my proposed interpretation based on Volker’s and Ian’s comments is the following:
		+	We’re seeing the interaction of a fast stream form the CH to the east with the May 27th post-CME flow. That flow (which admittedly is hard to see in regular images. You have to take my word on this at the moment) is likely coming from the area north of AR 11755. There’s a faint filament eruption from that QS neutral line on 5/27 ~9:36UT. So, there’s possibly organized magnetic field structure there which could be compressed in the CIR.

	=Image Data=		=Image Data=

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 * M. Temmer >> question: CME? or rather CIR which caused the intense geomagnetic storm of -125 nT?
 Jie Zhang: I believe that the slow/gradual May 27 CME is the cause of the intense geomagnetic storm. The CME in LASCO is not even close to a typical halo CME (JAVA movie in SEEDS: http://spaceweather.gmu.edu/seeds/dailymkmovie_ql.php?cme=20130527 ). The extremely faint arm across the equator at a later time indicates a partial halo nature. But as pointed out by Nariaki, it would have been regarded as a backside event, due to the lack of surface signature.
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 make the Bz large-though some of it must arise from the standard CIR velocity deflections.
-Ian Richardson: I tend to agree with Volker that this is a classic CIR with what looks like forward (5/31~18 UT) and reverse (6/2~02 UT) shocks (or developing shocks; I haven't looked at any high resolution data), and evidence of a stream interface (e.g., the increase in speed, temperature, decrease in density at 6/1~08 UT) within the CIR , preceded by the already noted sector boundary.  The slow-fast stream speed difference is quite large ~300-800 km/s, so this may account for the well formed CIR.  Here is a schematic of a CIR after Belcher and Davis 1971, with additions [http://www.uni-graz.at/~temmerma/download/varsiti/2013May31_Ian.png].
+Ian Richardson: I tend to agree with Volker that this is a classic CIR with what looks like forward (5/31~18 UT) and reverse (6/2~02 UT) shocks (or developing shocks; I haven't looked at any high resolution data), and evidence of a stream interface (e.g., the increase in speed, temperature, decrease in density at 6/1~08 UT) within the CIR , preceded by the already noted sector boundary.  The slow-fast stream speed difference is quite large ~300-800 km/s, so this may account for the well formed CIR.  Here is a schematic of a CIR after Belcher and Davis 1971, with additions [http://www.uni-graz.at/~temmerma/download/varsiti/2013May31_Ian.png]. [...]
 =Image Data=

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	Ian Richardson: I tend to agree with Volker that this is a classic CIR with what looks like forward (5/31~18 UT) and reverse (6/2~02 UT) shocks (or developing shocks; I haven't looked at any high resolution data), and evidence of a stream interface (e.g., the increase in speed, temperature, decrease in density at 6/1~08 UT) within the CIR , preceded by the already noted sector boundary. The slow-fast stream speed difference is quite large ~300-800 km/s, so this may account for the well formed CIR. Here is a schematic of a CIR after Belcher and Davis 1971, with additions [http://www.uni-graz.at/~temmerma/download/varsiti/2013May31_Ian.png].		Ian Richardson: I tend to agree with Volker that this is a classic CIR with what looks like forward (5/31~18 UT) and reverse (6/2~02 UT) shocks (or developing shocks; I haven't looked at any high resolution data), and evidence of a stream interface (e.g., the increase in speed, temperature, decrease in density at 6/1~08 UT) within the CIR , preceded by the already noted sector boundary. The slow-fast stream speed difference is quite large ~300-800 km/s, so this may account for the well formed CIR. Here is a schematic of a CIR after Belcher and Davis 1971, with additions [http://www.uni-graz.at/~temmerma/download/varsiti/2013May31_Ian.png].
		+
		+	Scanning our 2005 paper, the largest CIR storm we note is Dst = -161 nT (Table 2), so the current storm is certainly not out of bounds. Such infrequent storms typically require the CIR field to be southward for a few hours - that how you get a large storm - so if you see a large storm, then that's what you will see in the solar wind data. It may not necessarily be evidence of a transient, though we perhaps we have become "trained" to think that any feature with some organization is such a structure. I don't see any clear evidence that the southward field feature is a transient, but maybe if we had e.g., charge state data (unlikely given the SWICS problems) a more definitive conclusion could be made. Of course it would be interesting to understand how such southward fields could be produced by the stream interaction - clearly compression could produce the intensity, but is there, for example, some deflection due to the stream configuration that causes it to go south for a few hours?

	=Image Data=		=Image Data=

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 Bothmer Volker: I have been reluctant to comment on this earlier, but the in-situ data Show a classic CIR with sector boundary. No Need for CME search. Textbook CIR storm. Forward Shocks from HSS at 1Au are not so frequent but they occur.
-Dave Webb: I tend to agree with you; I had noted the distinct sector boundary right away. However, I am somewhat reluctant to put this to bed yet. First, the Dst>-100 nT is at the outer limits of what CIRs by themselves can produce (see, eg, Richardson, I.G. et al., JGR, 111, A07S09, 2006). The Dst is mostly driven by the very narrow, brief, strong Bsouth spike at early on June 1. And as earlier posts noted, there are several CME candidates, albeit weak, during this period that could have been compressed by the HSS. CMEs can erupt through the HCS and get caught up at sector boundaries. Is there evidence of ICME flow around this time (I again attach the ACE data plot)? There is the shock, and enhanced density and low T. There are also some rotations in the IMF which was enhanced for >1 day. What do others think about this?
+Dave Webb: I tend to agree with Volker B.; I had noted the distinct sector boundary right away. However, I am somewhat reluctant to put this to bed yet. First, the Dst>-100 nT is at the outer limits of what CIRs by themselves can produce (see, eg, Richardson, I.G. et al., JGR, 111, A07S09, 2006). The Dst is mostly driven by the very narrow, brief, strong Bsouth spike at early on June 1. And as earlier posts noted, there are several CME candidates, albeit weak, during this period that could have been compressed by the HSS. CMEs can erupt through the HCS and get caught up at sector boundaries. Is there evidence of ICME flow around this time (I again attach the ACE data plot)? There is the shock, and enhanced density and low T. There are also some rotations in the IMF which was enhanced for >1 day. What do others think about this?
 Janet Luhmann: [...] The key to the larger storm is of course the big -Bz that came with the June passage. This is about as big as a CIR storm can get from what I have read.  Also although there may not be a CME involved there could of course be some small transients (blobs or slow CME for ex.) that help