Last major update issued on August 3, 2013 at 05:30 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update July 1, 2013)] [Cycle 24 progress (last update August 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update August 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update August 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 1, 2013)]
[POES auroral activity level since October
2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated July 28, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was very quiet on August 2. Solar wind speed at SOHO ranged between 285 and 331 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 112.9 (decreasing 21.3 over the last solar rotation). The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.3). Three hour interval K indices: 11111110 (planetary), 02122312 (Boulder).
The background x-ray flux was at the class B2 level.
At midnight UTC the visible solar disk had 12 spotted active regions (in 2K resolution SDO images).
Region 11801 [N19W62] was quiet and stable.
Region 11806 [S14W18] gained a few spots and was quiet.
Region 11807 [N28W71] decayed slowly and quietly.
Region 11808 [N13E02] developed slowly and quietly.
Region 11809 [N12E42] developed slowly and quietly.
Region 11810 [S26E46] was quiet and stable.
Region 11811 [N06E13] decayed early in the day but regained spots after noon. Unfortunately USAF/SWPC failed to observe that AR S2583 had emerged to the west of AR 11811 as a new region and reassigned AR 11811 to what is AR S2583.
New region 11812 [S12W62] emerged on July 25 as AR S2570 and was numbered by SWPC 8 days later.
Spotted regions not numbered by SWPC:
S2574 [S09E06] has many penumbra spots and was quiet.
S2580 [S14E34] reemerged with a penumbra spot.
S2583 [N07E07] decayed slowly and quietly.
S2584 [S15E05] was quiet and stable.
July 31 - August 2: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
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 northern hemisphere coronal hole (CH577) rotated across the central meridian on July 31-August 1 and could become marginally geoeffective.
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 August 3-5 with a chance of unsettled and active intervals on August 3-4 if the high speed stream from CH577 becomes geoeffective.
|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
poor observation by USAF/SWPC, their location is that of AR S2583
real location: N06E13
|Total spot count:||32||113||42|
|Sunspot number:||112||233||142||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||63||144||73||(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):||67||82||78||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|
possible cycle 24 max
|2013.02||104.3||38.0||(57.8 projected, -0.9)||6.11|
|2013.03||111.3||57.9||(57.3 projected, -0.5)||10.56|
|2013.04||124.8||72.4||(57.3 projected, 0.0)||5.40|
|2013.05||131.4||78.7||(57.3 projected, 0.0)||9.73|
|2013.06||110.1||52.5||(57.6 projected, +0.3)||12.60|
|2013.07||115.5||57.0||(57.7 projected, +0.1)||9.33|
|2013.08||112.5 (1)||6.5 (2A) / 100.0 (2B) / 55.7 (2C)||(57.6 projected, -0.1)||(3.9)|
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.