Last major update issued on June 1, 2013 at 06:40 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update June 1, 2013)] [Cycle 24 progress (last update June 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update June 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 unsettled on May 31. Solar wind speed at SOHO ranged between 311 and 403 km/s. An apparent solar wind shock was observed at SOHO at 15:31 UTC. The inteplanetary magnetic field swung strongly southwards early on June 1 causing major storm conditions. The source of the disturbance could be a corotating active region associated with CH571.
Solar flux measured at 20h UTC on 2.8 GHz was 101.8 (decreasing 39.8 over the last solar rotation). The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.4). Three hour interval K indices: 00011333 (planetary), 11012333 (Boulder).
The background x-ray flux was at the class B2 level.
At midnight UTC the visible solar disk had 9 spotted active regions (in 2K resolution SDO images).
Region 11755 [N12W73] decayed slowly and quietly and lost the trailer
Region 11756 [S18W87] decayed slowly and quietly as it rotated to the southwest limb.
Region 11757 [S08W12] decayed slowly and quietly.
Region 11758 [S18E11] developed slowly and was mostly quiet.
Region 11760 [N11E39] has only small spots yet managed to produce an M1.0 flare at 20:00 UTC.
Region 11761 [S20E24] decayed slowly and was mostly quiet.
Spotted regions not numbered by SWPC:
S2446 [S18W17] lost the trailing spot.
S2451 [N18E32] reemerged with a penumbra spot.
S2454 [N13W43] was quiet and stable.
May 29-30: No obviously Earth directed CMEs were observed in LASCO and
May 31: Several CMEs were observed during the day, none of them with obvious Earth directed components. A large filament eruption across the central meridian in the northern hemisphere began near noon and lasted into the evening. The associated CME was directed northwards.
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 (CH571) was in an Earth facing position on May 29-30.
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 major storm on June 1 and quiet to active on June 2-3 due to effects associated with CH571.
|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:||8||45||15|
|Sunspot number:||58||135||55||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||24||56||26||(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):||35||47||30||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
|2012.12||108.6||40.8||(59.5 projected, -0.2)||3.44|
|2013.01||127.1||62.9||(59.1 projected, -0.4)||4.69|
|2013.02||104.3||38.0||(59.3 projected, +0.2)||6.11|
|2013.03||111.3||57.9||(58.9 projected, -0.4)||10.56|
|2013.04||124.8||72.4||(58.6 projected, -0.3)||5.40|
|2013.05||131.4||78.7||(58.7 projected, +0.1)||9.04|
|2013.06||(1)||0.0 (2A/2B) / 75.7 (2C)||(59.0 projected, +0.3)|
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.