Last major update issued on May 18, 2004 at 03:50 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update May 3, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update May 3, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update May 3, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update May 8, 2004)]
The geomagnetic field was quiet to unsettled on May 17. Solar wind speed ranged between 294 and 341 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 111.1. The planetary A
index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 6.8).
Three hour interval K indices: 21012322 (planetary), 11112232 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 6 spotted regions on the visible disk. The solar flare activity level was low. A single C class event was recorded during the day. Region 10614 rotated over the southwest limb and produced a C7.0 at 04:17 UTC.
Region 10606 decayed slowly and quietly.
Region 10609 decayed and lost about a third of its penumbral area.
Region 10612 decayed quickly and lost about half of the penumbral area and several spots.
Region 10613 was quiet and stable.
Region 10615 was quiet and stable.
New region 10617 emerged in the southeast quadrant on May 17. The region could become interesting as the inversion line currently runs nearly east-west.
May 15-17: No fully or partly Earth directed CME 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 small, recurrent coronal hole (CH96) in the southern hemisphere was in a geoeffective position on May 17.
Processed SOHO/EIT 284 image at 01:05 UTC on May 18. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on May 18-19 and quiet to active on May 20 due to effects from a weak coronal hole stream.
|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. 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: none, several stations were noted including Radio Vibración (Venezuela), Radio Cristal del Uruguay and Radio Rafaela (Argentina). Argentinean stations were noted on other frequencies as well (970, 1030, 1630 kHz) and propagation generally favored stations much further south than what was expected from the geomagnetic conditions. WWZN Boston on 1510 kHz had a good signal, otherwise North American stations were hard to hear.
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 CAO
at midnight, area 0050
classification was DAO
at midnight, area 0220
area was 0080
classification was HSX
at midnight, area 0090
|10614||2004.05.16||3||S08W89||0030||CAO||rotated out of view|
area was 0080
|Total spot count:||67||35|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2003.11||140.8||67.3||(56.5 predicted, -1.6)|
|2003.12||114.9||46.5||(53.5 predicted, -3.0)|
|2004.01||114.1||37.2||(49.1 predicted, -4.4)|
|2004.02||107.0||46.0||(44.8 predicted, -4.3)|
|2004.03||112.0||48.9||(42.1 predicted, -2.7)|
|2004.04||101.2||39.3||(40.0 predicted, -2.1)|
|2004.05||96.9 (1)||39.5 (2)||(36.8 predicted, -3.2)|
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.