Last major update issued on October 24, 2013 at 09:55 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update October 1, 2013)] [Cycle 24 progress (last update October 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update October 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update October 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update October 9, 2013)]
[POES auroral activity level since October
2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated October 10, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet on October 23. Solar wind speed at SOHO ranged between 275 and 467 km/s, early in the day under the influence of a weak disturbance.
Solar flux measured at 20h UTC on 2.8 GHz was 152.7 (increasing 42.8 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 114.4. The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4). Three hour interval K indices: 12210000 (planetary), 12111211 (Boulder).
The background x-ray flux was at the class C1 level.
At the time of counting spots (see image time) spots were observed in 12 active regions in 2K resolution (SN: 306) and 8 active regions in 1K resolution (SN: 168) SDO images on the visible solar disk.
Region 11872 [S17W36] was quiet and stable.
Region 11873 [N12W31] decayed slowly and quietly.
Region 11875 [N06W09] developed further but at a slower rate than on the previous days. The region has a strong magnetic delta structure centrally and could produce major flares. C5+ flares: C6.5 at 11:17, M2.7 at 20:53, M1.4 at 23:43 and an M3.1 event which began just before midnight and peaked at 00:08 UTC on Oct.24.
Region 11877 [S12E11] developed slowly with spots emerging around the large penumbra. The region was quiet most of the day, then became quite active before midnight and early on Oct.24 producing a major M9.3 flare at 00:30. The major flare was associated with a faint halo CME. C5+ flares: C8.7 at 22:26 UTC.
Region 11879 [S12E24] developed slowly and quietly.
Spotted regions not numbered by SWPC:
S2753 [N19W55] reemerged with penumbra spots.
S2769 [N15W16] was quiet and stable.
S2774 [S18W44] was quiet and stable.
S2775 [S22E53] was quiet and stable.
S2776 [N14E22] was quiet and stable.
New region S2778 [S09E84] rotated partly into view.
New region S2779 [S20W11] emerged with a penumbra spot.
October 21, 23: No obviously Earth directed CMEs were observed in LASCO and
October 22: A partial CME was observed early in the day following a filament eruption in the northeast quadrant. A small halo CME was associated with the M4 event in AR 11875 late in the day.
October 24: A faint halo CME was observed after the M9 event in AR 11877.
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 poor.
The geomagnetic field is expected to be quiet to unsettled on October 24. October 25 could see quiet to active conditions due to CME arrivals. On October 26 unsettled to minor storm conditions are possible due to effects from the CME observed early on Oct.24.
|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
|N23W86||actual location: N17W84|
|Total spot count:||91||186||88|
|Sunspot number:||141||306||168||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||121||227||124||(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):||87||107||92||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 peak)||96.7 (cycle peak)||61.1 (+1.2)||5.55|
likely cycle 24 max
|2013.04||124.8||72.4||(56.2 projected, -1.3)||5.40|
|2013.05||131.4||78.7||(55.8 projected, -0.4)||9.73|
|2013.06||110.1||52.5||(56.0 projected, +0.2)||12.60|
|2013.07||115.5||57.0||(56.1 projected, +0.1)||9.47|
|2013.08||114.6||66.0||(55.9 projected, -0.2)||8.27|
|2013.09||102.6||36.9||(55.4 projected, -0.5)||5.23|
|2013.10||123.9 (1)||86.5 (2A) / 116.7 (2B) / 66.6 (2C)||(53.9 projected, -1.5)||(8.95)|
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 the 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.