Last update issued on April 11, 2003 at 03:00 UTC.
[Solar and geomagnetic data - last 4 weeks (updated daily)]
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[Solar cycles 21-23 (last update April 2, 2003)]
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[Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2002 (last update January 27, 2003)]
[Archived reports (last update April 7, 2003)]
The geomagnetic field was unsettled to minor storm on April 10. Solar wind speed ranged between 496 and 722 km/sec, gradually increasing all day under the influence of a high speed stream from coronal hole CH31.
Solar flux measured at 20h UTC on 2.8 GHz was 103.7. The planetary A
index was 26 (STAR Ap - based on the mean of three hour interval ap indices: 26.1).
Three hour interval K indices: 35553343 (planetary), 35543443 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 3 spotted regions on the visible disk. Solar flare activity was very low.
Region 10330 developed a few spots ahead of the dominant penumbra while some of the small spots east of that penumbra
disappeared. One of the new negative leading spots was early on at the edge of the large positive polarity penumbra but had edged
slightly away by midnight.
Region 10332 decayed slowly and quietly and could soon become spotless.
New region 10334 rotated into view at the southeast limb on April 9 and was numbered the next day.
April 8-10: No obviously geoeffective CMEs observed.
Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28
days ago 27 days ago 26
days ago
A large coronal hole (CH31), mainly in the southern hemisphere, was in a geoeffective position on April 6-9. The eastern part of CH31 appears to be separating and is now CH32. CH32 will be in a geoeffective position on April 11-13.
Processed SOHO EIT 284 image at 13:06 UTC on April 10. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to minor storm on April 10-13 when the high speed stream from CH31 dominates the solar wind, isolated major storm intervals are possible on April 11 and 12. A high speed stream from CH32 will likely reach Earth late on April 13 or early on April 14 and dominate the solar wind until April 17 resulting in mostly unsettled to minor storm conditions. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor and will likely remain so at least until April 18, propagation along north-south paths is fair and could become fair to good over the next few days and remain fairly good until at least April 17. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay.]
| 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.
2) Material from a CME is likely to impact 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.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by SEC/NOAA. 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 SEC or where SEC has observed no spots.
| Solar region | Date numbered | SEC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10329 | 2003.04.03 | N02W74 | plage | ||||
| 10330 | 2003.04.03 | 16 | 11 | N07W16 | 0380 | CHI |
beta-gamma classification was DKO at midnight |
| 10331 | 2003.04.05 | 2 | S08W74 | 0020 | CRO |
became spotless late in the day |
|
| 10332 | 2003.04.07 | 2 | 2 | N11E18 | 0010 | AXX |
classification was HSX at midnight, area 0020 |
| 10333 | 2003.04.09 | N11W49 | plage | ||||
| 10334 | 2003.04.10 | 6 | 3 | S08E69 | 0110 | CAO | formerly region S135 |
| S134 | emerged on 2003.04.08 |
S18W05 | now spotless | ||||
| S136 | emerged on 2003.04.10 |
S22W41 |
emerged early in the day, then decayed and became spotless late in the day |
||||
| Total spot count: | 26 | 16 | |||||
| SSN: | 66 | 46 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2002.03 | 179.5 | 98.4 | 113.3 (-1.3) |
| 2002.04 | 189.8 | 120.7 | 110.5 (-2.9) |
| 2002.05 | 178.4 | 120.8 | 108.8 (-1.7) |
| 2002.06 | 148.7 | 88.3 | 106.2 (-2.6) |
| 2002.07 | 173.5 | 99.6 | 102.7 (-3.5) |
| 2002.08 | 183.6 | 116.4 | 98.7 (-4.0) |
| 2002.09 | 175.8 | 109.6 | 94.6 (-4.1) |
| 2002.10 | 167.0 | 97.5 | (91.0 predicted, -3.6) |
| 2002.11 | 168.7 | 95.0 | (85.7 predicted, -5.3) |
| 2002.12 | 157.2 | 81.6 | (81.3 predicted, -4.4) |
| 2003.01 | 144.0 | 79.5 | (78.3 predicted, -3.0) |
| 2003.02 | 124.5 | 46.2 | (73.3 predicted, -5.0) |
| 2003.03 | 131.4 | 61.5 | (67.6 predicted, -5.7) |
| 2003.04 | 132.3 (1) | 36.8 (2) | (62.7 predicted, -4.9) |
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number is typically 25-45% less.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.
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