Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 27, 2013 at 14:00 UTC. Normal updates are now resuming.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update January 1, 2013)] [Cycle 24 progress (last update January 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update January 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update January 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update January 2, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated January 8, 2013]

Recent activity

The geomagnetic field was quiet to active on January 26. Solar wind speed at SOHO ranged between 381 and 522 km/s under the influence of a high speed stream from CH550.

Solar flux measured at 20h UTC on 2.8 GHz was 99.4 (decreasing 7.3 over the last solar rotation). The Potsdam WDC planetary A index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 19.0). Three hour interval K indices: 42333444 (planetary), 41453334 (Boulder).

The background x-ray flux was at the class B1 level.

At midnight UTC the visible solar disk had 11 spotted active regions (in 2K resolution SDO images).

Region 11660 [N13W80] rotated partly out of view.
Region 11661 [N13E08] stretched out longitudinally and decayed quietly.
Region 11662 [N28E27] was quiet and stable.
New region 11663 [S11E47] emerged on January 25 and developed quickly the next day when it was numbered by SWPC.

Spotted regions not numbered by SWPC:
S2191 [N18W07] was quiet and stable.
New region S2196 [S30E49] emerged with tiny spots.
New region S2197 [N07E30] emerged with a few spots.
New region S2198 [N30W38] emerged quickly with many spots.
New region S2199 [N17E47] emerged with a tiny spot.
New region S2200 [S15E11] emerged with tiny spots.
New region S2201 [S13W20] emerged with a tiny spot.

Coronal mass ejections (CMEs)

January 24-26: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

Coronal holes

Coronal hole history (since October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A coronal hole (CH550) in the southern hemisphere was in an Earth facing position on January 21-22, however, CH550 closed on January 22.

Coronal hole map

The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, 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 this method, the extent and intensity of both CHs 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 fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 27 and quiet on January 28-29.

Coronal holes (1) Coronal mass ejection (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 2K resolution) Compare to the previous day's image. 0.5k 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 magnetic polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
2K 1K
11659 2013.01.16
2013.01.17
      N04W76           plage
11660 2013.01.17
2013.01.19
6 1 1 N13W81 0100 DAO HSX

 

S2184 2013.01.18       N18W49           plage
S2185 2013.01.20       S13W52           plage
11661 2013.01.21
2013.01.22
5 10 4 N15E08 0030 CRO BXI location: N13E08
S2187 2013.01.22       S29W19           plage
11662 2013.01.22
2013.01.23
1 3 1 N28E28 0050 HSX CSO  
S2189 2013.01.23       S18W31           plage
S2191 2013.01.24   2 2 N18W07 0010   BXO  
11663 2013.01.25
2013.01.26
3 12 5 S10E46 0010 BXO DSI area: 0090
S2194 2013.01.25       N19E15         plage
S2195 2013.01.25       N18W35         plage
S2196 2013.01.26   2   S30E49 0004   BXO    
S2197 2013.01.26   4 3 N07E30 0010   BXO    
S2198 2013.01.26   9 7 N30W38 0050   DRI    
S2199 2013.01.26   1   N17E47 0002   AXX    
S2200 2013.01.26   2   S15E11 0004   AXX    
S2201 2013.01.26   1   S13W20 0002   AXX    
Total spot count: 15 47 23  
Sunspot number: 55 157 93  (total spot count + 10 * number of spotted regions)
Weighted SN: 28 65 41  (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10)
Relative sunspot number (Wolf number): 33 55 51 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
2011.10 137.3 88.0 59.9 (+0.4) 8.28
2011.11 153.5 (cycle max) 96.7 (cycle max) 61.1 (+1.2) 5.55
2011.12 141.3 73.0 63.4 (+2.3) 3.78
2012.01 132.5 58.3 65.5 (+2.1) 7.15
2012.02 106.5 32.9 66.9 (+1.4)
possible cycle 24 max
8.81
2012.03 114.7 64.3 66.8 (-0.1) 16.08
2012.04 113.0 55.2 64.6 (-2.2) 10.10
2012.05 121.5 69.0 61.7 (-2.9) 7.06
2012.06 119.6 64.5 58.9 (-2.8) 10.08
2012.07 133.9 66.5 (57.4 projected, -1.5) 13.90
2012.08 115.4 63.1 (58.3 projected, +0.9) 7.96
2012.09 122.9 61.5 (58.9 projected, +0.6) 8.07
2012.10 123.3 53.3 (58.3 projected, -0.6) 9.97
2012.11 121.3 61.4 (57.6 projected, -0.7) 7.08
2012.12 108.6 40.8 (56.9 projected, -0.7) 3.44
2013.01 132.7 (1) 90.1 (2A) / 107.4 (2B) / 68.7 (2C) (56.2 projected, -0.7) (4.78)

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) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC 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.