Last major update issued on April 22, 2011 at 05:50 UTC.
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Annotated geomagnetic activity charts - Carrington rotation
2107 [Feb.-March
2011] - 2108 [March-April
2011] NEW
The geomagnetic field was quiet on April 21. Solar wind speed ranged between 407 and 457 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 113.0 (increasing 0.4 over the last solar rotation). The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.8). Three hour interval K indices: 12111212 (planetary), 12111222 (Boulder).
The background x-ray flux is at the class B8 level.
At midnight UTC the visible solar disk had 7 spotted regions.
Region 11191 decayed further and could become spotless today.
Region 11193 decayed losing spots and penumbral area.
Region 11195 developed slowly during the first half of the day, then more
quickly during the latter half. Early on April 22 the region has developed
rapidly and could soon become capable of producing a major flare. Flares:
C1.0 at 08:38, C8.5/1N at 09:48, C4.9 at 14:51 and C4.5 at 22:00 UTC.
Region 11196 was quiet and stable.
New region 11197 rotated into view at the southeast limb on April 19 and
was numbered by NOAA/SWPC two days later. Slow decay was observed on April 21.
New region 11198 was first observed with spots on April 19, then
became spotless on April 20 before reemerging with several spots on April 21.
Spotted regions not numbered by NOAA/SWPC:
[S965] emerged in the southeast quadrant on April 20. Location at midnight:
S18E21
April 19-21: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
Coronal hole history (since late 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 near Earth facing positions.
The darkest areas on the solar disk are likely coronal holes.
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 to fair.
The geomagnetic field is expected to be mostly quiet on April 22-24.
Coronal holes (1) | Coronal mass ejections (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 polarity overlay |
Comment | |||
---|---|---|---|---|---|---|---|---|---|---|
SWPC | STAR SDO | SWPC | STAR | Current | Previous | |||||
11191 | 2011.04.11 2011.04.12 |
1 | 3 | N08W52 | 0010 | HRX | BXO | location: N09W48 area: 0000 |
||
11193 | 2011.04.12 2011.04.13 |
20 | 21 | N16W32 | 0300 | EHI | EHI | |||
S950 | 2011.04.13 | S15W49 | plage | |||||||
S951 | 2011.04.13 | N28W61 | plage | |||||||
S953 | 2011.04.14 | N21W65 | plage | |||||||
S957 | 2011.04.17 | N08W59 | plage | |||||||
11195 | 2011.04.18 2011.04.19 |
10 | 31 | S17E43 | 0240 | DAI | DAC | beta-gamma |
||
S960 | 2011.04.18 | N10W08 | plage | |||||||
11196 | 2011.04.19 2011.04.20 |
4 | 15 | S26E63 | 0040 | CSO | CAO | location: S26E65 |
||
11197 | 2011.04.19 2011.04.21 |
1 | 2 | S16E57 | 0010 | AXX | AXX | formerly region S962 area: 0000 |
||
S963 | 2011.04.19 | S18E01 | plage | |||||||
11198 | 2011.04.19 2011.04.21 |
4 | 4 | S26W38 | 0010 | BXO | BXO | formerly region S964 | ||
S965 | 2011.04.20 | 6 | S18E21 | 0000 | AXX | |||||
S966 | 2011.04.20 | S32W38 | plage | |||||||
Total spot count: | 40 | 82 | ||||||||
Sunspot number: | 100 | 152 |
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 |
3.25 |
2010.02 | 84.7 | 18.8 | 10.6 (+1.3) | 4.15 / 4.61 |
2010.03 | 83.4 | 15.4 | 12.3 (+1.7) | 4.58 / 4.65 |
2010.04 | 75.9 | 8.0 | 14.0 (+1.7) | 10.22 / 10.24 |
2010.05 | 73.8 | 8.7 | 15.5 (+1.5) | 9.18 / 8.15 |
2010.06 | 72.5 | 13.6 | 16.4 (+0.9) | 8.17 / 6.85 |
2010.07 | 79.8 | 16.1 | 16.7 (+0.3) | 6.31 / 5.15 |
2010.08 | 79.2 | 19.6 | 17.4 (+0.7) | 8.49 / 7.77 |
2010.09 | 81.1 | 25.2 | 19.6 (+2.2) | 5.33 / 5.45 |
2010.10 | 81.6 | 23.5 | (22.6 predicted, +3.0) | 6.07 / 6.27 |
2010.11 | 82.5 | 21.5 | (25.7 predicted, +3.1) | 4.80 / 5.50 |
2010.12 | 84.2 | 14.4 | (28.9 predicted, +3.2) | 3.41 / 4.35 |
2011.01 | 83.6 | 19.1 | (31.9 predicted, +3.0) | 4.32 / 5.51 |
2011.02 | 94.6 | 29.4 | (34.4 predicted, +2.5) | 5.41 / 6.44 |
2011.03 | 115.0 | 56.2 | (36.7 predicted, +2.3) | 7.79 |
2011.04 | 112.7 (1) | 60.2 (2A) / 86.0 (2B) | (39.6 predicted, +2.9) | (10.61) |
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 preliminary daily SWPC ap indices.
Values in red are based on the official NGDC
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.