Last update issued on July 18, 2003 at 04:10 UTC.
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[Solar cycles 21-23 (last update July 2, 2003)]
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The geomagnetic field was unsettled to minor storm on July 17. Solar wind speed ranged between 567 and 771 km/sec, mostly under the influence of a high speed stream from coronal hole CH48.
Solar flux measured at 20h UTC on 2.8 GHz was 138.7. The planetary A
index was 22 (STAR Ap - based on the mean of three hour interval ap indices: 22.3).
Three hour interval K indices: 54333344 (planetary), 54344344 (Boulder).
The background x-ray flux is at the class B5 level.
At midnight there were 8 spotted regions on the visible disk. Solar flare activity was low. A total of 10 C class events was recorded during the day.
Region 10405 was quiet and stable.
Region 10408 was quiet and stable.
Region 10409 decayed quickly and lost about half of its penumbral area. Flare: C1.1 at 02:46 UTC.
Region 10410 developed quickly and became the largest region on the visible disk. Some polarity intermixing is obvious, and further flux emergence could cause magnetic delta structures to form. An M class flare is possible. Flares: C2.3 at 09:14, C2.6 at 15:29, C1.4 at 16:54, C2.8 at 17:44, C3.8 (associated with a weak to moderate type II radio sweep) at 18:40, C1.3 at 20:13 and C5.1 at 23:56 UTC.
Region 10411 was quiet and stable.
Region 10412 developed further and has a weak magnetic delta structure in the northwestern part. A minor M class flare is possible. Flares: C9.8/1N (M1.0 recorded by GOES10, this event was associated with moderate type II and IV radio sweeps) at 08:23 and C2.2 at 18:22 UTC.
Region 10413 was quiet and stable.
New region 10414 rotated into view at the southeast limb on July 16 and was numbered by SEC the next day.
July 15-16: No potentially geoeffective CMEs observed.
July 17: There may have been a faint CME associated with the C9 flare in region 10412.
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 coronal hole (CH48) in the northern hemisphere and with a large trans equatorial extension was in a geoeffective position on July 12-16.
Processed GOES SXI coronal structure image at 22:26 UTC on July 17. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to active on July 18 and quiet to active on July 19 due to a high speed stream from coronal hole CH48. CMEs associated with flares in regions 10410 and 10412 on July 17 could reach Earth on July 20 and cause an increase in geomagnetic activity.
Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay.]
|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.
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.
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.
|Solar region||Date numbered||SEC
|Location at midnight||Area||Classification||Comment|
|10401||2003.07.06||2||S09W90||0010||AXX||rotated out of view|
classification was HSX
at midnight, area 0050
classification was HRX
area was 0150
area was 0070
|10414||2003.07.17||1||1||S02E71||0090||HAX||formerly region S209|
|Total spot count:||99||111|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.01||144.0||79.7||(79.7 predicted, -2.3)|
|2003.02||124.5||46.0||(74.7 predicted, -5.0)|
|2003.03||131.4||61.1||(69.0 predicted, -5.7)|
|2003.04||126.4||60.0||(64.1 predicted, -4.9)|
|2003.05||115.7||55.2||(59.2 predicted, -4.9)|
|2003.06||129.3||77.4||(55.2 predicted, -4.0)|
|2003.07||130.5 (1)||75.9 (2)||(51.6 predicted, -3.6)|
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 interpretations, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.