Last major update issued on July 27, 2007 at 02:40 UTC.
geomagnetic data - last month (updated daily)]
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[Solar cycles 21-23 (last update July 23, 2007)]
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[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update July 23, 2007)]
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The geomagnetic field was quiet to active on July 26. Solar wind speed ranged between 271 and 548 km/s (average speed was 352 km/s, increasing 25 km/s over the previous day). A high speed stream from CH279 arrived at about 15h UTC at ACE.
Solar flux measured at 20h UTC on 2.8 GHz was 68.4. The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 8.6). Three hour interval K indices: 00011433 (planetary), 00122533 (Boulder).
The background x-ray flux is below the class A1 level.
At midnight the visible solar disk was spotless. The solar flare activity level was very low. No C class events were recorded during the day.
July 24-26: No obvious fully or partly Earth directed CMEs were observed.
history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A trans equatorial recurrent coronal hole (CH280) was in an Earth facing position on July 25-27.
Processed SOHO/EIT 195 image at 23:12 UTC on July 27. The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is fair to good.
Monitoring remarks from a location near N58E06: July 27: Lots of stations from Argentina, Brazil and Uruguay were heard early. 1070 Radio El Mundo had a good signal at 22:25 UTC, 1470 Radio Cristal was also strong then. A little later 1510 kHz was alive with several stations, Radio San Carlos (Uruguay) was dominant (and for such a small, distant station had an incredible signal). Propagation to North America was better than expected with strong signals from some Newfoundland stations (like 800 VOWR and 930 CJYQ), 1510 WWZN, 1520 WWKB, 1370 WDEA and others.
The geomagnetic field is expected to be quiet to unsettled on July 27 due to effects from CH279 and quiet on July 28. Another high speed stream (from CH280) could cause unsettled to active conditions on July 29-30.
|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.
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|
|Total spot count:||0||0|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2007.01||83.3||16.9||(11.9 predicted, -0.2)|
|2007.02||77.7||10.6||(11.3 predicted, -0.6)|
|2007.03||72.2||4.8||(10.8 predicted, -0.5)|
|2007.04||72.4||3.7||(10.8 predicted, unchanged)|
|2007.05||74.4||11.7||(10.6 predicted, -0.2)|
|2007.06||73.7||12.0||(10.7 predicted, +0.1)|
|2007.07||72.2 (1)||14.0 (2)||(11.0 predicted, +0.3)|
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.