Last major update issued on July 31, 2006 at 05:10 UTC.
geomagnetic data - last month (updated daily)]
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The geomagnetic field was quiet on July 29. Solar wind speed ranged between 350 and 469 km/s (all day average 405 km/s - decreasing 74 km/s from the previous day). A high speed stream from CH234 began to dominate the solar wind early on July 31.
Solar flux measured at 20h UTC on 2.8 GHz was 73.9. The planetary A index
was 5 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 22100112 (planetary), 22211112 (Boulder).
The background x-ray flux is at the class A2 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 10901 redeveloped a trailing spot while the leader spot
continued to lose penumbral area.
New region 10902 emerged quickly early in the day in the southwest quadrant, then began to decay slowly.
Spotted regions not numbered by NOAA/SEC:
[S669] This region emerged in the southwest quadrant on July 30. Polarities are reversed making this a candidate for the first cycle 24 region.
July 28-30: No partly or fully Earth directed CMEs were detected in LASCO imagery.
Coronal hole 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 well defined recurrent trans equatorial coronal hole (CH234) was in an Earth facing position on July 28-30.
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 major storm on July 31 and August 1 due to a high speed stream from CH234 becoming quiet to active on August 2 and quiet to unsettled on 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) 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 poor. Propagation on long distance northeast-southwest paths is fair. Propagation did not favor a particular area tonight. Stations from the easternmost parts of North America, from Venezuela, Perú, Brazil, Argentina and Uruguay were all heard. 1470 kHz had CPN Radio (Perú) dominating for at least 30 minutes around LSR.
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|
|10901||2006.07.22||1||3||N06W43||0010||HSX||classification was CAO at midnight, area 0030|
|10902||2006.07.30||2||2||S10W21||0030||CSO||classification was HAX at midnight, area 0020
|S669||2006.07.30||1||S12W55||0010||HRX||candidate cycle 24 region|
|Total spot count:||3||6|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2006.01||83.4||15.4||(20.7 predicted, -2.3)|
|2006.02||76.5||4.7||(18.2 predicted, -2.5)|
|2006.03||75.4||10.8||(16.4 predicted, -1.8)|
|2006.04||89.0||30.2||(15.7 predicted, -0.7)|
|2006.05||80.9||22.2||(14.9 predicted, -0.8)|
|2006.06||76.5||13.9||(12.7 predicted, -2.2)|
|2006.07||75.8 (1)||22.3 (2)||(11.3 predicted, -1.4)|
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% 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.