Last major update issued on April 2, 2012 at 03:40 UTC.
[Solar and geomagnetic data - last month (updated
daily)]
[Solar wind and electron fluence charts (updated
daily)
[Solar cycles 21-24 (last update
April 1, 2012)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last
update April 1, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and
24 (last update April 1, 2012)]
[Historical solar and geomagnetic data charts 1954-2006
(last update April 5, 2007)]
[Archived reports since January 2003 (last update
April 1, 2012)]
[POES auroral activity level since October
2009 - updated April 1, 2012]
Annotated geomagnetic activity charts - Carrington rotation
2118 [December 2011 - January 2012] -
2119 [January-February
2012]
[Solar polar fields vs solar cycles - updated
June 27, 2011]
The geomagnetic field was quiet to unsettled on April 1. Solar wind speed at SOHO ranged between 309 and 357 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 107.3 (decreasing 24.3 over the last solar rotation). The Potsdam WDC planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.0). Three hour interval K indices: 23222223 (planetary), 12222211 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight UTC the visible solar disk had 9 spotted active regions (in 2K resolution SDO images).
Region 11443 [N13W72] decayed slowly and quietly.
Region 11445 [S22W45] was quiet and stable.
Region 11448 [S17E17] decayed and could soon become spotless.
Region 11449 [S18W58] decayed and was quiet.
Region 11450 [N15E23] developed slowly and quietly.
Region 11451 [N17E40] decayed and could soon become spotless.
Spotted regions not reported by NOAA/SWPC:
[S1553] rotated into view at the southeast limb on March 27. Location at midnight:
S17E16
[S1558] emerged in the southeast quadrant on March 28. Location at
midnight: S30W28
[S1562] emerged near the northeast limb on March 31. Location at midnight:
N18E61
March 30-April 1: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
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 small coronal hole (CH510) in the northern hemisphere was in an Earth facing position on March 30. A new trans equatorial coronal hole (CH511) emerged near the central meridian on March 31.
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 fair.
The geomagnetic field is expected to be quiet to unsettled on April 2-4 with occasional active intervals due to weak effects from CH510 and CH511.
| 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 | ||||||||||
| 11443 | 2012.03.21 2012.03.22 |
2 | 2 | 1 | N14W74 | 0020 | CRO | BXO |
 |
 |
location: N13W72 |
| 11444 | 2012.03.22 2012.03.23 |
N21W86 |
plage location: N19W76 |
||||||||
| 11445 | 2012.03.23 | 1 | 3 | 3 | S23W45 | 0120 | HSX | CSO |
 |
 |
area: 0210 |
| 11448 | 2012.03.26 2012.03.28 |
2 | S17E01 | 0000 | AXX |
 |
 |
location: S17E07 | |||
| S1553 | 2012.03.27 | 4 | 2 | S17E16 | 0010 | BXO |
 |
 |
|||
| S1554 | 2012.03.27 | N16W55 | plage | ||||||||
| 11449 | 2012.03.28 2012.03.29 |
3 | 4 | 3 | S18W60 | 0040 | DSO | CRO |
 |
 |
|
| S1558 | 2012.03.28 | 3 | 1 | S30W28 | 0000 | BXO |
 |
 |
|||
| S1559 | 2012.03.29 | N22W58 | plage | ||||||||
| 11450 | 2012.03.30 2012.03.31 |
4 | 16 | 7 | N17E22 | 0020 | BXO | CRI |
 |
 |
location: N15E23 area: 0040 |
| 11451 | 2012.03.30 2012.03.31 |
2 | N17E39 | 0000 | AXX |
 |
 |
|
|||
| S1562 | 2012.03.31 | 5 | 3 | N18E61 | 0020 | CRO |
 |
 |
|||
| S1563 | 2012.03.31 | N26E05 |
 |
plage | |||||||
| Total spot count: | 10 | 41 | 20 | ||||||||
| Sunspot number: | 50 | 131 | 90 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted penumbral SN: | 23 | 55 | 35 | (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): | 30 | 46 | 50 | 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 (3) |
|---|---|---|---|---|
| 2008.07 | 65.7 (SF minimum) | 0.5 | 2.8 (-0.4) | |
| 2008.12 | 69.2 | 0.8 | 1.7 (-) sunspot minimum |
|
| 2011.01 | 83.6 | 19.1 | 31.0 (+2.2) | 5.51 |
| 2011.02 | 94.6 | 29.4 | 33.4 (+2.4) | 6.44 |
| 2011.03 | 115.0 | 56.2 | 36.9 (+3.5) | 8.18 |
| 2011.04 | 112.6 | 54.4 | 41.8 (+4.9) | 8.83 |
| 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 | (60.1 projected, +0.6) | 8.28 |
| 2011.11 | 153.5 | 96.7 | (61.6 projected, +1.5) | 5.55 |
| 2011.12 | 141.3 | 73.0 | (64.3 projected, +2.7) | 3.78 |
| 2012.01 | 132.5 | 58.3 | (67.8 projected, +3.5) | 7.15 |
| 2012.02 | 106.5 | 33.1 | (71.8 projected, +4.0) | 8.81 |
| 2012.03 | 114.7 | 64.2 | (73.9 projected, +2.1) | (20.17) |
| 2012.04 | 107.3 (1) | 1.7 (2A) / 50.0 (2B) | (74.9 projected, +1.0) | (9.0) |
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 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.
