Last major update issued on April 5, 2005 at 04:35 UTC.
[Solar and
geomagnetic data - last month (updated daily)]
[Solar wind and
electron fluence charts (updated daily)]
[Solar cycles 21-23
(last update April 4, 2005)]
[Solar cycles 1-20]
[Graphical comparison
of cycles 21, 22 and 23 (last update April 4, 2005)]
[Graphical
comparison of cycles 2, 10, 13, 17, 20 and 23 (last update April 4, 2005)]
[Historical solar and
geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports
(last update April 2, 2005)]
The geomagnetic field was quiet to minor storm on April 4. Solar wind speed ranged between 336 and 618 km/sec under the influence of a high speed stream from CH154. The interplanetary magnetic field was strongly southwards late in the day and caused severe storming early on April 5.
Solar flux measured at 20h UTC on 2.8 GHz was 84.8. The planetary
A
index was 17 (STAR Ap - based on the mean of three hour interval ap
indices: 17.1).
Three hour interval K indices: 12222445 (planetary), 12323444 (Boulder).
The background x-ray flux is at the class A7 level.
At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10747 developed early in the day, then began to decay slowly as the opposite polarity areas became better
separated.
Region 10748 was quiet and stable.
Region 10749 was quiet and stable.
April 2-4: No obvious fully or partly Earth directed CMEs were 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 recurrent coronal hole (CH154) in the northern hemisphere was in an Earth facing position on March 31-April 2. This coronal hole has decayed significantly over the last rotation and lost about half of its area. A coronal hole (CH155) in the southern hemisphere was in an Earth facing, potentially geoeffective, position on April 3.
Processed SOHO/EIT 284 image at 19:06 UTC on April 4. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to severe storm on April 5 due to effects from CH154. Unsettled conditions are possible on April 6 in relation to a stream from CH155. Quiet to unsettled is expected for April 7-8.
| 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) 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.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor to useless. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela) with a very weak signal. Only a few other trans Atlantic stations were noted with Rádio Sociedade (Brazil) on 740 kHz having the best signal.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. 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. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
| Active region | Date numbered | SEC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10747 | 2005.03.31 | 21 | 11 | S06W32 | 0110 | DAI | classification was DAO at midnight |
| 10748 | 2005.03.31 | 1 | 3 | N11E08 | 0020 | HSX | classification was CSO at midnight |
| 10749 | 2005.04.03 | 2 | 2 | S06E52 | 0040 | HSX | |
| S527 | emerged on 2005.03.24 |
N03W88 | plage | ||||
| S529 | emerged on 2005.03.28 |
S08W54 | plage | ||||
| S530 | emerged on 2005.03.28 |
N07W48 | plage | ||||
| Total spot count: | 24 | 16 | |||||
| SSN: | 54 | 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) |
| 2004.02 | 107.0 | 45.8 | 49.3 (-2.7) |
| 2004.03 | 112.0 | 49.1 | 47.1 (-2.2) |
| 2004.04 | 101.2 | 39.3 | 45.5 (-1.6) |
| 2004.05 | 99.8 | 41.5 | 43.8 (-1.7) |
| 2004.06 | 97.4 | 43.2 | 41.6 (-2.2) |
| 2004.07 | 119.1 | 51.1 | 40.2 (-1.4) |
| 2004.08 | 109.6 | 40.9 | 39.2 (-1.0) |
| 2004.09 | 103.1 | 27.7 | 37.5 (-1.7) |
| 2004.10 | 105.9 | 48.0 | (35.6 predicted, -1.9) |
| 2004.11 | 113.2 | 43.5 | (33.9 predicted, -1.7) |
| 2004.12 | 94.5 | 17.9 | (31.6 predicted, -2.3) |
| 2005.01 | 102.2 | 31.3 | (28.9 predicted, -2.7) |
| 2005.02 | 97.2 | 29.1 | (26.5 predicted, -2.4) |
| 2005.03 | 89.9 | 24.8 | (24.7 predicted, -1.8) |
| 2005.04 | 81.1 (1) | 4.9 (2) | (22.9 predicted, -1.8) |
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 (NOAA/SEC)
sunspot number. The official international sunspot number is typically
30-50% less.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.
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