Last major update issued on May 20, 2013 at 05:05 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update May 1, 2013)] [Cycle 24 progress (last update April 7, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update May 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update May 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update May 6, 2013)]
[POES auroral activity level since October
2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated May 12, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet to active on May 19. Solar wind speed at SOHO ranged between 348 and 442 km/s under the influence of CME effects. The CME associated with the M3 event on May 17 arrived at SOHO at 22:13 UTC when a solar wind shock was recorded. The interplanetary magnetic field has been predominantly northwards since then causing only minor geomagnetic effects.
Solar flux measured at 20h UTC on 2.8 GHz was 135.3 (increasing 22.4 over the last solar rotation). The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 10.5). Three hour interval K indices: 32222324 (planetary), 32323313 (Boulder).
The background x-ray flux was at the class B6 level.
At midnight UTC the visible solar disk had 10 spotted active regions (in 2K resolution SDO images).
Region 11744 [N07W64] decayed slowly and quietly.
Region 11745 [N14W40] decayed slowly and quietly.
Region 11746 [S28W37] displayed some interesting development in the trailing spot section as several penumbra spots and one umbra spot emerged with little sepatation between opposite polarity spots.
Region 11747 [S17W44] decayed slowly and quietly.
Region 11748 [N12W03] gained some small spots while the magnetic delta structure in the leading penumbra decayed further. The region was quiet.
Region 11750 [S09W69] lost all negative polarity umbrae, however, there are many spots within a fairly small area. Further C class flaring is possible. C5+ flare: C6.3 at 15:15 UTC.
Spotted regions not numbered by SWPC:
S2426 [S18E65] gained spots and was quiet.
New region S2427 [N04E78] rotated into view. Further C class flaring is likely. C5+ flare: long duration C9.9 peaking at 17:50 UTC. [Another AR slightly further north is near the northeast limb and may either have contributed to this event]
New region S2428 [N02W22] emerged with several spots. The region has a southern hemisphere polarity alignment.
New region S2429 [S21W15] emerged with a few penumbra spots.
May 18-19: No obviously Earth directed CMEs were observed in LASCO and
May 17: A halo CME was observed after an M3 event in AR 11748.
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
No obvious coronal holes are currently in or near Earth facing positions.
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.
The geomagnetic field is expected to be quiet to unsettled with a chance of active intervals on May 20 due to CME effects and quiet on May 21-22.
|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 2K resolution) Compare to the previous day's image. 0.5k image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue 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:||53||111||55|
|Sunspot number:||113||211||155||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||81||145||89||(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):||68||74||85||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 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
|2011.11||153.5 (cycle max)||96.7 (cycle max)||61.1 (+1.2)||5.55|
possible cycle 24 max
|2012.11||121.3||61.8||(59.1 projected, +0.5)||7.08|
|2012.12||108.6||40.8||(58.4 projected, -0.7)||3.44|
|2013.01||127.1||62.9||(58.0 projected, -0.4)||4.69|
|2013.02||104.3||38.0||(58.2 projected, +0.5)||6.11|
|2013.03||111.3||57.9||(57.8 projected, -0.4)||10.56|
|2013.04||124.8||72.4||(57.4 projected, -0.4)||5.40|
|2013.05||139.6 (1)||89.5 (2A) / 146.1 (2B) / 80.8 (2C)||(57.5 projected, +0.1)||(8.12)|
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) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
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.