Last major update issued on April 4, 2006 at 03:35 UTC.
[Solar and
geomagnetic data - last month (updated daily)]
[Solar wind and
electron fluence charts (updated daily)]
[Solar cycles 21-23
(last update April 1, 2006)]
[Solar cycles 1-20]
[Graphical comparison
of cycles 21, 22 and 23 (last update April 1, 2006)]
[Graphical
comparison of cycles 2, 10, 13, 17, 20 and 23 (last update April 1, 2006)]
[Historical solar and
geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update
April 3, 2006)]
The geomagnetic field was inactive to very quiet on April 3. Solar wind speed ranged between 273 and 302 (all day average 282) km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 100.4. The planetary A index
was 1 (STAR Ap - based on the mean of three hour interval ap
indices: 1.1).
Three hour interval K indices: 00000101 (planetary), 00001111 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 4 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 3 C class events were recorded during the day.
Region 10865 developed further in the intermediate spot section with
the penumbra trailing the leading spots gaining enough area to begin merging
with the leading penumbra. The magnetic delta structure has disappeared, however,
the region remains capable of producing C class flares. A minor M class event is
possible. Flare: C4.0 at 21:26 UTC.
Region 10866 saw the single penumbra split into two penumbrae.
Region 10867 developed slowly and has mixed polarities both in the
trailing and intermediate spot sections. Flares:
C1.8 at 12:03 and C1.4 at 16:25 UTC.
Sptted regions not numbered by NOAA/SEC:
[SW639] This region emerged in the southwest quadrant on April 3.
Location at midnight: S23W30.
April 1-3: No partly or fully Earth directed CMEs were observed in LASCO imagery.
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 small coronal hole (CH218) in the northern hemisphere may have been in an Earth facing position on April 3. A coronal hole (CH219) in the southern hemisphere will likely rotate to an Earth facing position on April 8.
Processed SOHO/EIT 284 image at 01:06 UTC on April 4. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet on April 4-6, possibly with some unsettled intervals on April 6 due to effects from CH218.
| 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.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is good. Propagation on long distance northeast-southwest paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: WLAM Lewiston ME and Radio Vibración (Venezuela). Many stations from the eastern half North America were audible, several with good to excellent signals.
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 |
|---|---|---|---|---|---|---|---|
| 10865 | 2006.03.28 | 31 | 23 | S11W21 | 0330 | EKI | classification was EKC at midnight, area 0600 |
| 10866 | 2006.03.29 | 6 | 4 | S06E05 | 0120 | CAO | |
| 10867 | 2006.04.02 | 12 | 16 | S16E03 | 0100 | DAO | beta-gamma classification was DAI at midnight |
| S639 | 2006.04.03 | 1 | S23W30 | 0010 | AXX | ||
| Total spot count: | 49 | 44 | |||||
| SSN: | 79 | 84 | |||||
| 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) |
| 2005.01 | 102.2 | 31.3 | 34.6 (-0.6) |
| 2005.02 | 97.2 | 29.2 | 33.9 (-0.7) |
| 2005.03 | 89.9 | 24.5 | 33.5 (-0.4) |
| 2005.04 | 86.0 | 24.2 | 31.6 (-1.9) |
| 2005.05 | 99.3 | 42.7 | 28.9 (-2.7) |
| 2005.06 | 93.7 | 39.3 | 28.8 (-0.1) |
| 2005.07 | 96.4 | 40.1 | 29.1 (+0.3) |
| 2005.08 | 90.5 | 36.4 | 27.4 (-1.7) |
| 2005.09 | 91.1 | 21.9 | 25.8 (-1.6) |
| 2005.10 | 77.0 | 8.5 | (24.8 predicted, -1.0) |
| 2005.11 | 86.3 | 18.0 | (22.7 predicted, -2.1) |
| 2005.12 | 90.7 | 41.2 | (19.8 predicted, -2.9) |
| 2006.01 | 83.4 | 15.4 | (16.7 predicted, -3.1) |
| 2006.02 | 76.5 | 4.7 | (13.6 predicted, -3.1) |
| 2006.03 | 75.4 | 10.8 | (11.4 predicted, -2.2) |
| 2006.04 | 92.8 (1) | 6.0 (2) | (10.7 predicted, -0.7) |
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% lower.
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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