Solar Terrestrial Activity Report

The geomagnetic field was quiet to unsettled on June 15. Solar wind speed ranged between 503 and 634 km/s (average speed was 558 km/s, increasing 62 km/s over the previous day) under the influence of a high speed stream from CH272.

Solar flux measured at 20h UTC on 2.8 GHz was 69.1. The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.6). Three hour interval K indices: 23212212 (planetary), 24321222 (Boulder).

At midnight the visible solar disk was spotless. The solar flare activity level was very low. No C class events were recorded during the day.

Coronal mass ejections (CMEs)

June 13-15: No obvious fully or partially Earth directed CMEs were observed in LASCO imagery.

Coronal holes

A recurrent coronal hole (CH273) in the southern hemisphere will likely rotate into an Earth facing position on June 17-19.

Processed SOHO/EIT 195 image at 00:00 UTC on June 16. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on June 16 and quiet on June 17-19. A high speed stream from CH273 could cause unsettled to minor storm conditions on June 20-22.

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.

Propagation

Daily monitoring will not resume until a local noise problem (related to construction work on a neighboring property) has been fixed. Occasional monitoring reports will be submitted when propagation is good.

April 8, 2007: Stations from the Canadian Atlantic provinces had strong signals during the night. Some stations from the northeastern USA and from Florida did well too, in particular 1510 WWZN was impressive.

Active solar regions (Recent map)

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

Month	Average solar flux at Earth	International sunspot number	Smoothed sunspot number
2000.04	184.2	125.5	120.8 cycle 23 sunspot max.
2000.07	202.3	170.1	119.8
2001.12	235.1	132.2	114.6 (-0.9)
2006.04	89.0	30.2	17.1 (-0.3)
2006.05	80.9	22.3	17.3 (+0.2)
2006.06	76.5	13.9	16.3 (-1.0)
2006.07	75.7	12.2	15.3 (-1.0)
2006.08	79.0	12.9	15.6 (+0.3)
2006.09	77.8	14.4	15.6 (+0.0)
2006.10	74.3	10.4	14.2 (-1.4)
2006.11	86.3	21.5	12.7 (-1.5)
2006.12	84.5	13.6	(12.1 predicted, -0.6)
2007.01	83.3	16.9	(11.7 predicted, -0.4)
2007.02	77.7	10.6	(11.1 predicted, -0.6)
2007.03	72.2	4.8	(10.7 predicted, -0.4)
2007.04	72.4	3.7	(10.9 predicted, +0.2)
2007.05	74.4	11.7	(11.0 predicted, +0.1)
2007.06	78.5 (1)	16.4 (2)	(11.3 predicted, +0.3)

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% lower.

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.

Active region	SEC spot count	STAR spot count

Total spot count:	0	0
SSN:	0	0

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