Last major update issued on March 13, 2013 at 05:00 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update March 1, 2013)] [Cycle 24 progress (last update March 2, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update March 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update March 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update March 1, 2013)]
[POES auroral activity level since October
2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated February 3, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet on March 12. Solar wind speed at SOHO ranged between 290 and 328 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 123.0 (increasing 22.8 over the last solar rotation). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.4). Three hour interval K indices: 11112121 (planetary), 11212212 (Boulder).
The background x-ray flux was at the class B4 level.
At midnight UTC the visible solar disk had 12 spotted active regions (in 2K resolution SDO images).
Region 11687 [N07W51] decayed slowly and quietly.
Region 11689 [S19W41] decayed slowly and quietly.
Region 11690 [N24W08] has polarity intermixing. A long duration C2.0/1F event peaking at 11:07 UTC was centered over this region as a filament erupted.
Region 11691 [N12W13] developed slowly and quietly.
Region 11692 [N09E37] was quiet and stable.
Region 11694 [N15E38] decayed slowly and quietly.
Region 11695 [N10E59] was mostly quiet and stable.
Region 11696 [N04E20] developed further and has polarity intermixing. Further C class flares are possible. A C3.6 flare at 21:43 UTC appears to have had its origin in this region. The flare may have triggered a nearby filament eruption which began at 22:44 UTC and peaked early on March 13 as a long duration C1.8 event.
Spotted regions not numbered by SWPC:
S2278 [S20W15] was quiet and stable.
S2286 [N09W04] was quiet and stable.
New region S2287 [S25E83] rotated into view.
New region S2288 [N13E01] emerged with a single spot.
March 10-11: No obviously Earth directed CMEs were observed in LASCO
March 12: A weak partial halo CME was observed in LASCO imagery from the combined ejecta of the C2 LDE near the central meridian and a filament eruption in the northeast quadrant. While imagery is very limited as I write this, a STEREO-B image hints at the possibility of an Earth directed CME in association with the C1 LDE near AR 11696 late in the day.
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 small northern hemisphere coronal hole (CH559) was in an Earth facing position on March 11.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on March 13-15. The CME observed early on March 13 could reach Earth on March 16 and cause unsettled to active conditions.
|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:||25||107||42|
|Sunspot number:||95||227||122||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||55||141||76||(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):||57||79||67||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
|2012.09||122.9||61.4||(57.9 projected, -0.2)||8.07|
|2012.10||123.3||53.3||(57.0 projected, -0.9)||9.97|
|2012.11||121.3||61.4||(56.1 projected, -0.9)||7.08|
|2012.12||108.6||40.8||(54.9 projected, -1.2)||3.44|
|2013.01||127.1||62.9||(53.6 projected, -1.3)||4.69|
|2013.02||104.3||38.0||(52.5 projected, -1.1)||6.11|
|2013.03||115.8 (1)||34.9 (2A) / 90.1 (2B) / 47.5 (2C)||(51.5 projected, -1.0)||(7.71)|
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.