Last major update issued on July 31, 2004 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 July 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update July 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update July 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update July 1, 2004)]
The geomagnetic field was quiet to unsettled on July 30. Solar wind speed ranged between 449 and 566 km/sec. A weak solar wind shock was observed at SOHO at 20:41 UTC. This was likely related to the partial halo CME observed on July 28 following a very long duration C4 event. The shock only caused a minor increase in geomagnetic activity.
Solar flux measured at 20h UTC on 2.8 GHz was 88.7. The planetary A
index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 8.1).
Three hour interval K indices: 21123223 (planetary), 21112323 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 2 spotted regions on the visible disk. The solar flare activity level was low. A total of 1 C class event was recorded during the day. This was a C1.2 flare at 07:31 from region 10652 behind the northwest limb.
Region 10654 developed slowly in the intermediate spot section, this part of the region has some polarity intermixing.
New region 10655 rotated into view at the southeast limb on July 29 and was numbered the next day by SEC.
July 29-30: No obvious Earth directed 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
No obvious coronal holes are currently approaching geoeffective positions.
Processed SOHO/EIT 284 image at 01:06 UTC on July 31. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on July 31 - August 3.
|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. Propagation along long distance north-south paths is fair. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. After local sunrise several stations from Argentina were heard, the best propagation was above 1400 kHz. No stations from North America were observed.
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|
classification was DAO
|10655||2004.07.30||1||2||S09E71||0110||HAX||formerly region S440|
|Total spot count:||13||18|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2004.01||114.1||37.7||(51.1 predicted, -3.7)|
|2004.02||107.0||45.8||(46.9 predicted, -4.2)|
|2004.03||112.0||49.1||(44.1 predicted, -2.8)|
|2004.04||101.2||39.3||(42.1 predicted, -2.0)|
|2004.05||99.8||41.5||(38.8 predicted, -3.3)|
|2004.06||97.4||43.2||(36.0 predicted, -2.8)|
|2004.07||120.2 (1)||85.9 (2)||(34.2 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.