Last major update issued on April 4, 2005 at 03:25 UTC.
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 on April 3. Solar wind speed ranged between 289 and 354 km/sec. A weak low speed stream from CH154 only caused a mild increase in geomagnetic activity.
Solar flux measured at 20h UTC on 2.8 GHz was 81.1. The planetary
index was 6 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 12111222 (planetary), 12211322 (Boulder).
The background x-ray flux is at the class A6 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 further and was quiet until late in the day when minor, persistent sub flare activity was
observed. C flares are possible.
Region 10748 was quiet and stable.
New region 10749 rotated into view at the southeast limb on April 2 and was numbered by SEC on April 3.
April 1-3: No obvious fully or partly Earth directed CMEs were observed.
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 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 to minor storm on April 4-5 due to effects from CH154. Unsettled conditions are possible on April 6 in relation to a stream from CH155.
|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 fair to good. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: WLAM Lewiston ME. Surprisingly WAZN Watertown MA was noted on top of WLAM for a few minutes. Stations in the Boston (850 WEEI, 1030 WBZ, 1060 WBIX, 1510 WWZN) and New York (660, 770, 880, 1050 and 1560 kHz) areas had the best signals with peaks to S9+10dB.
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
|Location at midnight||Area||Classification||Comment|
|10747||2005.03.31||6||14||S05W09||0060||DAO||classification was DAI at midnight, area 0100|
|10748||2005.03.31||1||1||N11E20||0010||HSX||area was 0020 at midnight|
formerly region S532
classification was HAX at midnight, area 0040
|Total spot count:||8||16|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|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||79.9 (1)||3.1 (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.