Solar Terrestrial Activity Report

The geomagnetic field was quiet to unsettled on June 30. Solar wind speed ranged between 285 and 355 km/s. ACE data indicate that the leading part of a high speed stream from CH460 arrived at 16h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 89.2 (decreasing 17.9 over the last solar rotation). The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.3). Three hour interval K indices: 22102232 (planetary), 12101211 (Boulder).

Region 11242 developed early in the day, then began to decay.
Region 11243 developed slowly and was quiet. C flares are possible.

Spotted regions not numbered by NOAA/SWPC:
[S1087] emerged in the northeast quadrant on June 27. The region developed significantly on June 30 and has mixed polarities. Location at midnight: N13E02
[S1088] reemerged with a few tiny spots on June 30. Location at midnight: S27W06
[S1090] emerged at the northeast limb on June 29. Location at midnight: N15E62
[S1092] emerged in the southeast quadrant on June 30. Location at midnight: S23E19

Interesting bipolar regions with no spots emerged at high latitudes (N78 and S60) during the day.

Coronal mass ejections (CMEs)

Coronal holes

A recurrent coronal hole (CH460) in the northern hemisphere was in an Earth facing position on June 27-28. A small coronal hole (CH461) in the northern hemisphere was in an Earth facing position on June 30, however, CH461 has decayed over the last days and closed on June 30. A trans equatorial coronal hole (CH462) could become Earth facing on July 1-2.

The above coronal hole map is based on a new method where coronal holes are detected automatically. The method may need some fine tuning, however, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using the new method, the extent and intensity of both holes are consistent with other data sources.

Propagation

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.

Forecast

The geomagnetic field is expected to be quiet to active on July 1 with a chance of minor storm intervals due to effects from CH460. Quiet to unsettled is likely on July 2-3.

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) 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

When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) is positive.

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 detected	Spot count	Location at midnight	Area	Classification	SDO / HMI 4K continuum image with polarity overlay	Comment
SWPC	STAR SDO	SWPC	STAR	Current	Previous
S1079	2011.06.23			N10W45				plage
S1083	2011.06.24			N25W54				plage
11242	2011.06.26 2011.06.28	8	19	N16W30	0080	DSO	DAO
11243	2011.06.27 2011.06.28	6	22	N16E36	0030	CRO	DRI	northwestern spots could be separate region
S1087	2011.06.27		11	N13E02	0030		CRO	beta-gamma
S1088	2011.06.27		3	S27W06	0000		AXX
S1089	2011.06.28			S23W32				plage
S1090	2011.06.29		2	N15E62	0000		AXX
S1091	2011.06.29			S23E04				plage
S1092	2011.06.30		1	S23E19	0000		AXX
Total spot count:	14	58
Sunspot number:	34	118

Monthly solar cycle data

Month	Average measured solar flux	International sunspot number (SIDC)	Smoothed sunspot number	Average ap (3)
2008.07	65.7 (SF minimum)	0.5	2.8 (-0.4)
2008.12	69.2	0.8	1.7 (-) sunspot minimum	3.25
2010.02	84.7	18.8	10.6 (+1.3)	4.15 / 4.61
2010.03	83.4	15.4	12.3 (+1.7)	4.58 / 4.65
2010.04	75.9	8.0	14.0 (+1.7)	10.22 / 10.24
2010.05	73.8	8.7	15.5 (+1.5)	9.18 / 8.15
2010.06	72.5	13.6	16.4 (+0.9)	8.17 / 6.85
2010.07	79.8	16.1	16.7 (+0.3)	6.31 / 5.15
2010.08	79.2	19.6	17.4 (+0.7)	8.49 / 7.77
2010.09	81.1	25.2	19.6 (+2.2)	5.33 / 5.45
2010.10	81.6	23.5	23.2 (+3.6)	6.07 / 6.27
2010.11	82.5	21.5	26.5 (+3.3)	4.80 / 5.50
2010.12	84.2	14.4	(29.4 predicted, +2.9)	3.41 / 4.35
2011.01	83.6	19.1	(32.6 predicted, +3.2)	4.32 / 5.51
2011.02	94.6	29.4	(35.2 predicted, +2.6)	5.41 / 6.44
2011.03	115.0	56.2	(37.5 predicted, +2.3)	7.79
2011.04	112.6	54.4	(40.4 predicted, +2.9)	9.71
2011.05	95.8	41.6	(43.7 predicted, +3.3)	9.18
2011.06	95.8 (1)	55.6 (2A/2B)	(47.4 predicted, +3.7)	(8.96)

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 SIDC international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the preliminary 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.

Coronal holes (1)	Coronal mass ejections (2)	M and X class flares (3)