Last major update issued on July 27, 2012 at 03:35 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-24 (last update June 2, 2012)] [Cycle 24 progress NEW]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 2, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update June 2, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 1, 2012)]
[POES auroral activity level since October
2009 - updated July 17, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]
The geomagnetic field was very quiet on July 26. Solar wind speed at SOHO ranged between 309 and 372 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 114.7 (decreasing 2.7 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: 2.8). Three hour interval K indices: 10101100 (planetary), 00112211 (Boulder).
The background x-ray flux is at the class B5 level.
At midnight UTC the visible solar disk had 10 spotted active regions (in 2K resolution SDO images).
Region 11525 [S21W70] decayed slowly and quietly retaining only a
single tiny spot.
Region 11526 [S17W12] added spots and lost rudimentary penumbra on the leader spots.
Region 11527 [N25E28] was quiet and stable.
Region 11528 [N17E26] was quiet and stable.
Region 11529 [S11E31] was quiet and stable.
Region 11530 [S18E41] was quiet and stable.
New region 11531 [N15W57] was first observed with spots on July 19, then was spotless for several days until July 25 when quick development was observed. SWPC numbered the region one day later.
New region 11532 [S20E69] rotated partly into view on July 25 and was numbered the next day by SWPC. The region is close to an FSO classification. C flares are possible and there is a slight chance of an M class flare.
Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1819 [N22E18] decayed with only a single tiny spot remaining at the end of the day.
New region S1824 [S28E30] emerged with several spots.
An unusually large filament system is situated across the equator between the active regions in the northern and southern parts of the eastern hemisphere. The filament system appears to be stable but should be watched for activity as an eruption while it is near the central meridian could cause a major geomagnetic storm.
A filament eruption near the northeast limb was observd late in the day and was associated with a CME off the northeast limb and north pole.
July 24-26: 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 recurrent trans equatorial coronal hole (CH525) was in an Earth facing position on July 25-27.
The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using this method, the extent and intensity of both CHs are consistent with other data sources.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on July 27. A high speed stream from CH525 could cause unsettled to minor storm conditions on July 28-30.
|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 higher resolution image) Compare to the previous day's image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) 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:||17||76||35|
|Sunspot number:||77||176||105||(total spot count + 10 * number of spotted regions)|
|Weighted penumbral SN:||45||110||69||(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):||46||62||58||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) 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
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|2012.01||132.5||58.3||(65.0 projected, +1.6)||7.15|
|2012.02||106.5||33.1||(66.5 projected, +1.5)||8.81|
|2012.03||114.7||64.2||(67.2 projected, +0.7)||16.08|
|2012.04||113.0||55.2||(66.5 projected, -0.7)||10.10|
|2012.05||121.5||69.0||(64.8 projected, -1.7)||7.06|
|2012.06||119.6||64.5||(64.0 projected, -0.8)||10.08|
|2012.07||134.4 (1)||83.5 (2A) / 99.5 (2B)||(65.0 projected, +1.0)||(15.58)|
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) Month average to date.
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.