Solar Terrestrial Activity Report

Last major update issued on November 28, 2010 at 05:30 UTC.

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The geomagnetic field was quiet to major storm on November 27. Solar wind speed ranged between 294 and 530 km/s. An unusual and unexpected disturbance was observed beginning at SOHO near 13h UTC with an abrupt increase in solar wind density. No significant changes were observed in solar wind speed until after 17h UTC, then the wind speed increased fairly quickly until 22h UTC. Solar wind density varied significantly over the same time interval and became high again late in the day. Solar wind temperature fluctuated between high (often associated with coronal high speed streams) and normal. Due to the complex and unusual behavior of different solar wind parameters, it is difficult to determine the source of the disturbance. SWPC is claiming this was a recurrent high speed coronal hole stream, however, that is not supported by data one solar rotation ago (no disturbance then). Furthermore SWPC has published conflicting geomagnetic data for the peak of this disturbance. While magnetometer data indicates major storming during the last hour of the 18-21h UTC interval, SWPC is using Kp 4 in their graphs. According to the magnetometer data the disturbance was much stronger at mid latitudes than at high latitudes with several stations reporting severe storming.

Solar flux measured at 20h UTC on 2.8 GHz was 76.5 (down 4.7 over the last solar rotation). The planetary A index  was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.9). Three hour interval K indices: 00001164 (planetary), 00001243 (Boulder).

The background x-ray flux is at the class A5 level.

At midnight UTC the visible solar disk had 3 spotted regions.

Region 11127 decayed further and had only a tiny spot left by the end of the day.

Spotted regions not numbered by NOAA/SWPC:
[S841] This region emerged early in the day on November 27 near the southwest limb. Location at midnight: S25W61
[S842] A new region emerged in the northeast quadrant on November 27. Location at midnight: N14E14

November 25-27: No obviously Earth directed CMEs were observed in LASCO or STEREO images.

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

No significant coronal holes are currently in or near Earth facing positions.

Image courtesy of SDO (NASA) and the AIA consortium. Annotations are my own. The darkest areas on the solar disk are likely coronal holes.

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor Propagation on long distance northeast-southwest paths is poor to fair.

The geomagnetic field is expected to be quiet to unsettled with a chance of active or even minor storm intervals on November 28 and quiet on November 29-30.

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.

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/SWPC. 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 SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.

Active region	Date numbered	Spot count		Location at midnight	Area	Classification		SDO (NASA) / AIA 4500 image		Comment
		SWPC	STAR			SWPC	STAR	Current	Previous
11127	2010.11.15	1	1	N24W71	0030	HSX	AXX			area: 0000
11128	2010.11.25			S14E33						plage
S841	2010.11.27		3	S25W61	0010		BXO
S842	2010.11.27		4	N14E14	0010		BXO
Total spot count:		1	8
Sunspot number:		11	38

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the daily SWPC ap indices. Values in red are based on the official NGDC ap indices.

This report has been prepared by Jan Alvestad. It is based on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.