Last major update issued on June 18, 2004 at 03:55 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update June 14, 2004)]
The geomagnetic field was quiet to unsettled on June 17. Solar wind speed ranged between 454 and 567 km/sec under the influence of a weak high speed stream from coronal hole CH102.
Solar flux measured at 20h UTC on 2.8 GHz was 111.3. 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: 13222232 (planetary), 22232232 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 4 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.
Region 10631 decayed slowly and will rotate to the southwest limb late today.
Region 10632 was quiet and stable.
Region 10634 developed further in the leading spot section with negative polarity spots emerging just south of the large positive polarity penumbra. Slow decay was observed in the trailing spot section. A minor M class flare is possible. Flare: C1.2 at 02:41 UTC.
Region 10635 developed in the trailing spot section and could produce a minor M class flare.
June 15-17: No fully or partly 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
A recurrent trans equatorial coronal hole (CH102) was in a geoeffective position on June 14-15.
Processed SOHO/EIT 284 image at 13:05 UTC on June 15. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on June 18-20 with a chance of active intervals on June 18 due to a high speed stream from coronal hole CH102.
|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 poor to very poor. Propagation along long distance north-south paths is fair to good. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. Radio Vibración (Venezuela) was noted at times. After local sunrise propagation was again best towards Argentina, Uruguay and Brazil. Radio Real (Uruguay) on 1590 kHz had a nice signal. An interesting Spanish speaking station was heard above the dominant Brazilian station on 740 kHz for a few minutes. The only North American station noted was WWZN on 1510 kHz with a weak to occasionally fair signal. WDHP on 1620 had a good signal and Caribbean Beacon on 1610 kHz had a better than usual signal.
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 HRX
at midnight, area 0010
|Total spot count:||56||73|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.12||114.9||46.5||(54.4 predicted, -2.3)|
|2004.01||114.1||37.2||(50.5 predicted, -3.9)|
|2004.02||107.0||46.0||(46.2 predicted, -4.3)|
|2004.03||112.0||48.9||(43.5 predicted, -2.7)|
|2004.04||101.2||39.3||(41.4 predicted, -2.1)|
|2004.05||99.8||41.5||(38.2 predicted, -3.2)|
|2004.06||92.6 (1)||39.3 (2)||(35.3 predicted, -2.9)|
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.