Last major update issued on July 28, 2006 at 04:25 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update July 19, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update July 19, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update July 19, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update July 9, 2006)]
The geomagnetic field was quiet to active on July 27. Solar wind speed ranged between 315 and 582 km/s (all day average 381 km/s - increasing 35 km/s over the previous day). A high speed stream from CH233 became the dominant solar wind source after noon and caused a significant geomagnetic disturbance towards the end of the day and early on July 28. The planetary A index for the 00-03h UTC interval on July 28 was 94.
Solar flux measured at 20h UTC on 2.8 GHz was 74.4. The planetary A index
was 9 (STAR Ap - based on the mean of three hour interval ap
Three hour interval K indices: 10002234 (planetary), 11112124 (Boulder).
The background x-ray flux is at the class A2 level.
At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10901 was mostly quiet and stable.
July 25-27: 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 coronal hole (CH233) in the northern hemisphere had poorly defined southward extensions that were in Earth facing locations on July 23-24. A well defined recurrent trans equatorial coronal hole (CH234) will reach an Earth facing location on July 29-30.
Processed SOHO/EIT 284 image at 01:06 UTC on July 28. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to major storm on July 28 and quiet to active on July 29 due to coronal hole effects. Mostly quiet conditions are expected for July 30 and 31. Late on July 31 or early on August 1 a strong high speed stream from CH234 can cause unsettled to minor storm conditions lasting until August 2.
|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 very poor. Propagation on long distance northeast-southwest paths is good. Between 01 and 02h UTC a few stations from North America were still audible (Newfoundland on 620, 710, 740, 800, 930 and 1210 kHz and 1510 WWZN). Only a few stations from South America were audible before LSR. After LSR the band opened towards Brazil, Argentina and Uruguay with many stations audible. Strong signals from Argentina were noted on 700, 710, 780, 790, 870, 910, 950, 1110, 1190, 1270 and 1450 kHz.
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||13||4||N05E00||0070||CSO||classification was CAO at midnight|
|Total spot count:||13||4|
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||76.1 (1)||20.4 (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.