Last major update issued on August 19, 2012 at 04:05 UTC.
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The geomagnetic field was quiet to active on August 18. Solar wind speed at SOHO ranged between 334 and 458 km/s. Effects from CH529 became noticable after 14h UTC with solar wind speed increasing slowly from 360 km/s at 18h to above 450 km/s by the end of the day.
Solar flux measured at 20h UTC on 2.8 GHz was 97.0 (increasing 3.3 over the last solar rotation). The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 9.9). Three hour interval K indices: 12222243 (planetary), 12332333 (Boulder).
The background x-ray flux is at the class B3 level.
At 06 UTC (due to image processing lag HMI imagery at 06h UTC were the latest available at the time of writing this) the visible solar disk had 6 spotted active regions (in 2K resolution SDO images).
Region 11543 [N23W73] lost penumbral area, however, the single
penumbra is interesting with positive polarity flux emerging in its center.
Region 11546 [N16E46] was quiet and stable.
Region 11547 [N06E09] decayed slowly and quietly.
New region 11548 [N19E73] rotated partly into view on August 17. The
region has been very active and the source of 5 impulsive M flares and many C
flares during the day. Further M class flaring is likely.
Flares above the C5 level: major M5.5 at 01:02,
M1.8 at 03:23, C6.1 at 06:18, C7.3 at 14:27, M2.0/1N at 16:07, M1.0 at 22:54,
M1.3 at 23:22 UTC.
Spotted regions not numbered by SWPC:
S1862 [N13W38] developed slowly and quietly.
New region S1866 [S18W11] emerged with tiny spots in an old plage area.
August 16, 18: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
August 17: A large filament eruption near AR 11543 starting at 22h UTC
was the source of a wide and bright CME. While the major part of the CME was
directed northwards, there may have been a weak Earth directed component. A weak glancing blow is possible on
August 21.
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
A recurrent coronal hole (CH529) in the southern hemisphere was Earth facing on August 15-16.
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 fair.
The geomagnetic field is expected to be quiet to active on August 19 due to effects from CH529. On August 20-21 mostly quiet conditions are likely with a chance of weak CME effects on August 21.
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. 0.5k image [NEW]
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 | ||||||||||
11543 | 2012.08.06 2012.08.07 |
3 | 6 | 2 | N23W74 | 0300 | HHX | CKO |
|
||
S1856 | 2012.08.14 | N13W23 | plage | ||||||||
S1857 | 2012.08.14 | S19W56 | plage | ||||||||
11546 | 2012.08.15 2012.08.16 |
1 | 1 | 1 | N16E44 | 0050 | HSX | HSX |
location: N16E46 area: 0090 |
||
11547 | 2012.08.16 2012.08.17 |
2 | 6 | 3 | N06E09 | 0010 | CRO | DRO | |||
S1861 | 2012.08.16 | N23E10 | plage | ||||||||
S1862 | 2012.08.16 | 5 | 3 | N13W38 | 0010 | BXO | |||||
11548 | 2012.08.17 2012.08.18 |
8 | 6 | 4 | N20E76 | 0120 | CAO | DAO | |||
S1865 | 2012.08.17 | S28E04 | plage | ||||||||
S1866 | 2012.08.18 | 2 | S18W11 | 0000 | AXX | ||||||
Total spot count: | 14 | 26 | 13 | ||||||||
Sunspot number: | 54 | 86 | 63 | (total spot count + 10 * number of spotted regions) | |||||||
Weighted SN: | 37 | 49 | 36 | (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): | 32 | 30 | 35 | 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 | 32.9 | (67.4 projected, +1.9) | 8.81 |
2012.03 | 114.7 | 64.3 | (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) | 13.90 |
2012.08 | 121.0 (1) | 52.8 (2A) / 90.9 (2B) | (68.6 projected, +2.6) | (8.15) |
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.