Solar Terrestrial Activity Report

Last major update issued on January 14, 2004 at 04:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 4, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 4, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 4, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update October 15, 2003)]
[Archived reports (last update January 9, 2004)]

Recent activity

The geomagnetic field was quiet to active on January 13. Solar wind speed ranged between 459 and 594 km/sec. An unexpected disturbance arrived at SOHO between 08 and 09h UTC, solar wind speed increased from 468 km/sec at 08:09 to 594 km/sec at 09:08 UTC. Solar wind density didn't increase until after 11:43 UTC. The source of this disturbance is uncertain. Based on solar wind speed the date of origin at the sun was most likely January 10.

Solar flux measured at 20h UTC on 2.8 GHz was 117.9. The planetary A index was 18 (STAR Ap - based on the mean of three hour interval ap indices: 18.8).
Three hour interval K indices: 33324443 (planetary), 33415443 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight there were 5 spotted regions on the visible disk. Solar flare activity was low. A total of 7 C class events was recorded during the day. A C1.0 flare from a region behind the northeast limb was recorded at 12:28 UTC.

Region 10536 decayed further as it rotated to the southwest limb. Flares: C1.1 at 01:33, C2.0 at 02:46 and C1.7 at 03:29 UTC.
Region 10537 decayed with the large penumbra becoming smaller. There is still a magnetic delta in the southeastern part of this penumbra and an M flare is possible. Flares: C1.5 at 06:09, C1.0 at 07:36 and C1.1 at 13:24 UTC.
Region 10540 rotated fully into view. The region is somewhat complex in magnetograms with a leading negative polarity spot, then a narrow band of positive polarity and a narrow band of negative polarity, then the main positive polarity area and finally a band of negative polarity. At least C class flares are possible.

Spotted regions not numbered by NOAA/SEC:
[S330] This region emerged early on January 13 in the southeast quadrant, then lost all spots before gaining new spots just before midnight. Location at midnight: S07E23.
[S331] A new region emerged near the northwest limb on January 13, just northwest of spotless region 10538. Location at midnight: N10W72.

There is an unusually large and dense filament in the northeast quadrant, it is stretching in a near semicircle from the equator at E50 to N40 at E60 through the westernmost point at N08E25. An eruption of this filament will cause a large CME.

Coronal mass ejections (CMEs)

January 13: No partly or fully earth directed CMEs observed.

January 12: A CME was observed over the northwest limb, the north pole and part of the northeast limb late in the day. This slow CME was probably associated with an erupting filament in the northwest quadrant.

January 11: A CME was observed off of the southeast limb during the evening, it probably had a backsided origin. 

Coronal holes

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 (CH76) will rotate into a geoeffective position on January 13-16, the coronal hole is well defined in the northern and central parts.

Processed SOHO/EIT 284 image at 01:06 UTC on January 14. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 14-15 with unsettled to minor storm conditions possible from noon on January 16 until January 18 because of a high speed stream from coronal hole CH76.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along long distance north-south paths is fair to good. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay on the southwesterly antenna, at times with interference from one or two stations from Brazil. Radio San Carlos (Uruguay) on 1510 kHz was noted as well, and there was a large number of Brazilean stations on other frequencies].

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.

Active solar regions (Recent map)

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.

Monthly solar cycle data

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 sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.