Last major update issued on May 9, 2012 at 04:35 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2118 [December 2011 - January 2012] - 2119 [January-February 2012]
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The geomagnetic field was quiet to active on May 8. Solar wind speed at SOHO ranged between 285 and 461 km/s. A high speed stream associated with CH515 became the dominant solar wind source after 18h UTC.
Solar flux measured at 20h UTC on 2.8 GHz was 122.8 (increasing 29.6 over the last solar rotation). The Potsdam WDC planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.4). Three hour interval K indices: 23122224 (planetary), 12123323 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight UTC the visible solar disk had 13 spotted active regions (in 2K resolution SDO images).
Region 11470 [S17W67] decayed slowly and quietly.
Region 11471 [S22W63] decayed slowly and quietly.
Region 11474 [N14W10] decayed slowly and quietly.
Region 11475 [N12W02] lost the southernmost spot and gained a spot in the northern part of the same polarity area.
Region 11476 [N10E33] has developed slowly with a strong magnetic delta structure forming in the southern part of the huge leading penumbra. Another strong delta with nearly no distance between opposite polarity umbrae is in a penumbra in the northern central part of the region. A major flare will become likely if the current development continues. Flares: M1.4/1F at 13:08 as well as a few C1 events.
New region 11477 [S22E74] rotated into view at the southeast limb on May 7 and was numbered the next day by SWPC.
Spotted active regions not numbered by NOAA/SWPC:
New region S1635 [S24E83] rotated into view at the southeast limb as a single symmetrical penumbra.
New region S1636 [S17E32] emerged with a tiny spot.
New region S1637 [N23W02] emerged with a single spot.
New region S1638 [S21W06] emerged with 2 spots.
New region S1639 [S16W18] emerged with a tiny spot.
New region S1640 [S16W33] emerged with a single spot.
New region S1641 [N11W27] emerged with a single spot.
May 6: No obviously Earth directed CMEs were observed in STEREO imagery.
May 7: The M1.9 event in region 11471 may have had a weak Earth directed component. The most interesting CME of the day was observed after a filament erupted in the southeast quadrant beginning near 21:15 UTC. STEREO-B displays a CME late on May 7 and early on May 8 which could easily be Earth directed, neither STEREO-A nor LASCO imagery from the relevant time is currently available.
May 8: A filament eruption beginning at 09:45 UTC near AR 11474 across the central meridian was the source of a small CME observed in both STEREO-A and B imagery after 11h UTC. While most of the ejected material was over the northern limbs, it appears that a part of the CME is Earth directed.
Coronal hole history (since October
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A recurrent trans equatorial coronal hole (CH515) was in an Earth facing position on May 5-7. Another recurrent trans equatorial coronal hole (CH516) will become Earth facing on May 9-10.
The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using this method, the extent and intensity of both CHs are consistent with other data sources.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair to good.
The geomagnetic field is expected to be unsettled to minor storm on May 9-10 due to a high speed stream from CH515 becoming quiet to active on May 11. quiet initially on May 8. The CME observed late on May 7 could reach Earth on May 10 and contribute to the ongoing disturbance. The CME observed on May 8 could reach Earth on May 11. Starting late on May 12 or early on May 13 a high speed stream from CH516 could cause quiet to active conditions until May 14.
|Coronal holes (1)||Coronal mass ejection (2)||M and X class flares (3)|
1) Effects from a coronal hole could reach Earth within the
next 5 days. When the high speed stream has arrived the color changes to
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
Click on image for higher resolution image) Compare to the previous day's image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) is positive.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.
|Active region||Date numbered
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with magnetic polarity overlay
|Total spot count:||40||98||55|
|Sunspot number:||90||228||145||(total spot count + 10 * number of spotted regions)|
|Weighted penumbral SN:||63||123||80||(Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10)|
|Relative sunspot number (Wolf number):||54||80||80||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) for STAR SDO 2K, k = 0.55 for STAR SDO 1K|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|2011.11||153.5||96.7||(61.2 projected, +1.3)||5.55|
|2011.12||141.3||73.0||(63.9 projected, +2.7)||3.78|
|2012.01||132.5||58.3||(67.4 projected, +3.5)||7.15|
|2012.02||106.5||33.1||(71.4 projected, +4.0)||8.81|
|2012.03||114.7||64.2||(73.5 projected, +2.1)||16.08|
|2012.04||113.0||55.2||(74.5 projected, +1.0)||10.10|
|2012.05||116.4 (1)||25.1 (2A) / 97.1 (2B)||(75.8 projected, +1.3)||(6.19)|
1) Running average based on the daily 20:00 UTC observed solar flux value at
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official SIDC international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC ap indices.
This report has been prepared by Jan Alvestad. It is based on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.