Solar Terrestrial Activity Report

Last major update issued on June 4, 2011 at 06:25 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update June 1, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 1, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update June 1, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update June 1, 2011)]

[POES auroral activity level charts since October 2009 - updated June 1, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2108 [March-April 2011] - 2109 [April-May 2011]
[Solar polar fields vs solar cycles - updated May 26, 2011] NEW

Recent activity

The geomagnetic field was quiet on June 3. Solar wind speed ranged between 375 and 450 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 107.1 (increasing 4.9 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.1). Three hour interval K indices: 21101112 (planetary), 21111111 (Boulder).

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

At midnight UTC the visible solar disk had 10 spotted regions.

Region 11225 was quiet and stable.
Region 11226 developed further in the southern spot section and has polarity intermixing. C flares are likely and there is a chance of a minor M class flare. Flares: C2.5 at 06:17, C1.6 at 22:42 UTC.
Region 11227 was quiet and stable.
Region 11228 was quiet and stable.
Region 11229 decayed slowly and was quiet.
Region 11230 decayed and could soon become spotless.
Region 11231 was quiet and stable.
Region 11232 was quiet and stable.

Spotted regions not numbered by NOAA/SWPC:
[S1044] was split off from region 11227 on June 1. The region is decaying and lost penumbra on the leader spots. Location at midnight: S19W03.
[S1046] emerged in the northeast quadrant on June 3. Location at midnight: N15E35

Coronal mass ejections (CMEs)

June 1: A slow, faint full halo CME was observed after the C4 event at 17:08 UTC in and to the north of region 11226.
June 2: A slow, faint full halo CME was observed in association with the C3 event at 07:46 UTC to the north of region S1044.
June 3: No earth directed CMEs were observed.

Coronal holes

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

A poorly defined weak coronal area or coronal hole (CH453) across the equator between regions S1044 and 11228 will be Earth facing on June 4.

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.

Forecast

The geomagnetic field is expected to be quiet on June 4. If the high speed stream associated with CH452 arrives there's a chance of unsettled and active intervals. The CME observed on June 1 could arrive late on June 4 or on June 5 and cause unsettled to minor storm conditions while the CME observed on June 2 likely will arrive on June 5 and cause unsettled to minor storm conditions until June 6. On June 7 effects from CH453 could arrive and cause some unsettled intervals with a chance of active intervals.

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) 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

(Click on image for higher resolution image) Compare to the previous day's image

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
11225 2011.05.25
2011.05.27
1 5 N17W35 0010 AXX CRO location: N15W31
11226 2011.05.27 21 38 S22W14 0340 DKC DAI beta-gamma
S1033 2011.05.28     S18W43           plage
11228 2011.05.28
2011.05.29
10 21 N18E05 0150 DAO CSO

location: N16E06

11227 2011.05.28
2011.05.29
4 13 S19W00 0120 CSO CSO

location: S22E06

area: 0080

11229 2011.05.29
2011.05.30
1 9 N17W20 0010 AXX BXO location: N16W17
11230 2011.05.30
2011.05.31
2 7 N19E15 0010 AXX BXO

location: N18E18

11232 2011.05.31
2011.06.01
1 2 N10E46 0070 HSX HSX

location: N08E47

11231 2011.06.01
2011.06.02
2 8 N10E33 0010 BXO BXO

location: N08E35

S1044 2011.06.01   3 S19W03 0020   BXO split off from 11227 on June 1
S1045 2011.06.01     S22W39           plage
S1046 2011.06.03   1 N15E35 0000   AXX    
Total spot count: 42 107  
Sunspot number: 122 207  

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
2011.06 110.8 (1) 11.6 (2A) / 115.7 (2B) (47.4 predicted, +3.7) (8.04)

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.

SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.