Last major update issued on March 29, 2004 at 04:10 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update March 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update March 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update March 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update January 16,
2004)]
[Archived reports (last update March 28, 2004)]
The geomagnetic field was quiet to minor storm on March 28. Solar wind speed ranged between 610 and 985 km/sec under the influence of a high speed stream from coronal hole CH87.
Solar flux measured at 20h UTC on 2.8 GHz was 129.0. The planetary A
index was 17 (STAR Ap - based on the mean of three hour interval ap indices: 17.5).
Three hour interval K indices: 35333322 (planetary), 45333421 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 7 spotted regions on the visible disk. The solar flare activity level was low. A total of 4 C class events was recorded during the day. A C1.2 flare at 04:43 UTC was not optically correlated.
Region 10577 decayed slowly and quietly. The region could become spotless before rotating over the southwest limb late
today and early tomorrow.
Region 10578 decayed further and could become spotless today.
Region 10581 was quiet and stable.
Region 10582 decayed significantly with penumbra disappearing to the southeast and northeast of the main penumbra. Several
new, small spots emerged. Flares: C1.0 at 00:08 and C1.8 long duration event peaking at 12:44
UTC.
Region 10584 decayed and is likely to become spotless early today.
Region 10585 developed slowly. Flare: C1.3 at 03:55 UTC.
New region 10587 rotated into view at the southeast limb. C flares are possible.
March 26-28: No partly or fully earth directed CMEs observed in limited LASCO data.
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 (CH87) in the northern hemisphere was in a geoeffective position on March 25-27.
Processed SOHO/EIT 284 image at 00:12 UTC on March 18. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on March 29-31 due to a high speed stream from coronal hole CH87.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along long distance north-south paths is poor to fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). WWZN Boston on 1510 kHz was noted, as were a few of the most common Newfoundland stations].
| 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.
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 |
|---|---|---|---|---|---|---|---|
| 10577 | 2004.03.17 | 1 | 1 | S03W68 | 0020 | HAX | |
| 10578 | 2004.03.18 | 2 | 3 | N14W57 | 0020 | HSX |
classification was BXO at midnight, area 0010 |
| 10579 | 2004.03.22 | S13W32 | plage | ||||
| 10580 | 2004.03.24 | S06W60 | plage | ||||
| 10581 | 2004.03.24 | 1 | 1 | S03E24 | 0140 | HAX | |
| 10582 | 2004.03.25 | 23 | 36 | N15E30 | 0390 | DKI | beta-gamma |
| 10583 | 2004.03.27 | 3 | N08W81 | 0040 | BXO | spotless | |
| 10584 | 2004.03.27 | 4 | 6 | S13E08 | 0030 | CAO |
classification was BXO at midnight, area 0010 |
| 10585 | 2004.03.27 | 7 | 13 | S14E40 | 0050 | DAI | |
| 10587 | 2004.03.28 | 4 | 5 | S13E73 | 0110 | DAI |
classification was CAO at midnight, area 0070 |
| Total spot count: | 45 | 65 | |||||
| SSN: | 125 | 135 | |||||
| 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) |
| 2003.02 | 124.5 | 46.0 | 78.3 (-2.5) |
| 2003.03 | 131.4 | 61.1 | 74.0 (-4.3) |
| 2003.04 | 126.4 | 60.0 | 70.1 (-3.9) |
| 2003.05 | 115.7 | 55.2 | 67.6 (-2.5) |
| 2003.06 | 129.3 | 77.4 | 65.0 (-2.6) |
| 2003.07 | 127.7 | 83.3 | 61.8 (-3.2) |
| 2003.08 | 122.1 | 72.7 | 60.0 (-1.8) |
| 2003.09 | 112.2 | 48.7 | (58.9 predicted, -1.1) |
| 2003.10 | 151.7 | 65.5 | (56.2 predicted, -2.7) |
| 2003.11 | 140.8 | 67.3 | (53.5 predicted, -2.7) |
| 2003.12 | 114.9 | 46.5 | (50.9 predicted, -2.6) |
| 2004.01 | 114.1 | 37.2 | (46.7 predicted, -4.2) |
| 2004.02 | 107.0 | 46.0 | (42.1 predicted, -4.6) |
| 2004.03 | 110.6 (1) | 68.5 (2) | (39.7 predicted, -2.4) |
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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