Last major update issued on August 5, 2012 at 05:40 UTC.
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The geomagnetic field was quiet to unsettled on August 4. Solar wind speed at SOHO ranged between 341 and 423 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 138.7 (decreasing 39.0 over the last solar rotation). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.5). Three hour interval K indices: 12211113 (planetary), 11213322 (Boulder).
The background x-ray flux is at the class B6 level.
At 20h UTC the visible solar disk had 10 spotted active regions (in 2K resolution SDO images).
Region 11530 [S19W78] was quiet and stable.
Region 11532 [S20W51] decayed further losing all penumbra on the trailing
spots.
Region 11534 [N22W36] was quiet and stable.
Region 11535 [N18W02] decayed slowly producing a few small C flares
during the first half of the day.
Region 11537 [N12E24] was quiet and stable.
Region 11538 [S23E17] displayed slow decay and was quiet.
Region 11539 [S22E33] decayed slowly and was mostly quiet.
Region 11540 [S27E45] gained several small spots and lost penumbra on the
trailing spots.
Region 11541 [S16E51] decayed slowly and quietly.
Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1842 [N17E12] was quiet and stable.
The only interesting event during the day was a very long duration C3.5 event beginning just after 11h and peaking at 15:00 UTC. Its source was a large filament eruption in the southeast quadrant from about 40 degrees east to the central meridian and from near the equator in the north to ARs 11539 and 11538 in the south. The event was associated with a full halo asymmetric CME. Earth is probably outside the path of the core CME, however, an impact is likely on August 7.
August 2-3: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
August 4: A full halo CME was associated with a large filament eruption
in the southeeast quadrant, the CME could influence Earth on August 7-8.
Coronal hole history (since October
2002)
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 close to geoeffective positions.
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. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on August 5-6. The CME from the August 4 eruption could reach Earth on August 7 and cause unsettled to minor storm conditions until August 8.
| 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
green.
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 detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlay |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC | STAR SDO | SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 11529 | 2012.07.22 2012.07.23 |
1 | S11W88 | 0030 | HSX |
 |
rotated out of view | ||||
| 11530 | 2012.07.23 2012.07.24 |
1 | 1 | 1 | S18W78 | 0100 | HSX | HSX |
 |
 |
area: 0160 |
| 11532 | 2012.07.25 2012.07.26 |
4 | 12 | 5 | S19W53 | 0240 | CSO | CHO |
 |
 |
area: 0330 location: S20W51 |
| 11534 | 2012.07.27 2012.07.28 |
3 | 1 | N23W40 | 0000 | AXX |
 |
 |
location: N22W36 | ||
| 11535 | 2012.07.29 2012.07.30 |
10 | 22 | 13 | N18W02 | 0100 | CSO | CSI |
 |
 |
beta-gamma area: 0220 |
| 11536 | 2012.07.30 | 3 | S25W38 | 0030 | CSO | part of AR 11532 | |||||
| 11537 | 2012.07.31 | 1 | 1 | 1 | N12E23 | 0050 | HSX | HSX |
 |
 |
|
| 11538 | 2012.07.31 | 8 | 17 | 8 | S22E16 | 0220 | ESO | ESO |
 |
 |
area: 0400 |
| S1835 | 2012.07.31 | N12W16 | plage | ||||||||
| 11539 | 2012.08.01 2012.08.02 |
3 | 4 | 3 | S22E31 | 0020 | CRO | CRO |
 |
 |
|
| S1837 | 2012.08.01 | N27W07 | plage | ||||||||
| 11541 | 2012.08.02 2012.08.03 |
1 | 3 | 1 | S15E50 | 0000 | AXX | AXX |
 |
 |
location: S16E51 |
| 11540 | 2012.08.02 2012.08.03 |
8 | 13 | 7 | S27E46 | 0090 | CAO | CAI |
 |
 |
area: 0130 |
| S1840 | 2012.08.02 | N09E02 | plage | ||||||||
| S1841 | 2012.08.02 | N06W69 |
 |
plage | |||||||
| S1842 | 2012.08.03 | 3 | 3 | N17E12 | 0010 | BXO |
 |
 |
|||
| Total spot count: | 40 | 79 | 42 | ||||||||
| Sunspot number: | 140 | 179 | 142 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted penumbral SN: | 83 | 117 | 80 | (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): | 84 | 63 | 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 (3) |
|---|---|---|---|---|
| 2011.05 | 95.8 | 41.6 | 47.6 (+5.8) | 8.94 |
| 2011.06 | 95.8 | 37.0 | 53.2 (+5.6) | 8.06 |
| 2011.07 | 94.2 | 43.9 | 57.2 (+4.0) | 8.16 |
| 2011.08 | 101.7 | 50.6 | 59.0 (+1.8) | 7.26 |
| 2011.09 | 133.8 | 78.0 | 59.5 (+0.5) | 12.27 |
| 2011.10 | 137.3 | 88.0 | 59.9 (+0.4) | 8.28 |
| 2011.11 | 153.5 | 96.7 | 61.1 (+1.2) | 5.55 |
| 2011.12 | 141.3 | 73.0 | 63.4 (+2.3) | 3.78 |
| 2012.01 | 132.5 | 58.3 | 65.5 (+2.1) | 7.15 |
| 2012.02 | 106.5 | 33.1 | (67.4 projected, +1.9) | 8.81 |
| 2012.03 | 114.7 | 64.2 | (68.1 projected, +0.7) | 16.08 |
| 2012.04 | 113.0 | 55.2 | (67.5 projected, -0.6) | 10.10 |
| 2012.05 | 121.5 | 69.0 | (65.8 projected, -1.7) | 7.06 |
| 2012.06 | 119.6 | 64.5 | (65.0 projected, -0.8) | 10.08 |
| 2012.07 | 133.9 | 66.5 | (66.0 projected, +1.0) | 14.37 |
| 2012.08 | 138.7 (1) | 17.5 (2A) / 136.0 (2B) | (68.6 projected, +2.6) | (9.28) |
1) Running average based on the daily 20:00 UTC observed solar flux value at
2800 MHz.
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.
