Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 25, 2013 at 03:10 UTC. Note: Updates will be irregular until January 28.

[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 October 7, 2012]
[Solar polar fields vs solar cycles - updated January 8, 2013]

Recent activity

The geomagnetic field was very quiet on January 24. Solar wind speed at SOHO ranged between 274 and 301 km/s. A solar sector change was noted just before 01 UTC on January 25.

Solar flux measured at 20h UTC on 2.8 GHz was 103.4 (decreasing 3.4 over the last solar rotation). The Potsdam WDC planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.0). Three hour interval K indices: 11000000 (planetary), 11010100 (Boulder).

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

At midnight UTC the visible solar disk had 7 spotted active regions (in 2K resolution SDO images).

Region 11658 [S12W86] was quiet and stable.
Region 11660 [N13W57] lost some area in the leader spots while several trailing spots merged into one penumbra.
Region 11661 [N13E33] gained a few spots and was quiet.
Region 11662 [N28E53] was quiet and stable.

Spotted regions not numbered by SWPC:
S2184 [N18W23] reemerged with a tiny spot.
New region S2191 [N14E19] emerged with a tiny spot.
New region S2192 [S28W54] emerged with tiny spots.

Coronal mass ejections (CMEs)

January 22, 24: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
January 23: A partial halo CME was observed after a filament eruption in the northeast quadrant (to the west of AR 11662). This CME could reach Earth on January 26 or 27.

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 fair. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 25 due to weak coronal hole effects. On January 26 or 27 the CME observed on January 23 could reach Earth and cause some unsettled and active intervals.

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
11658 2013.01.12
2013.01.13
1 1   S12W73 0060 HSX HSX location: S12W86
11659 2013.01.16
2013.01.17
      N04W48         plage
11660 2013.01.17
2013.01.19
16 19 9 N10W56 0180 DAO DAO

location: N12W57

S2182 2013.01.17       N17W48         plage
S2184 2013.01.18   1   N18W23 0001   AXX   plage
S2185 2013.01.20       S13W26         plage
11661 2013.01.21
2013.01.22
2 5 4 N17E33 0020 DSO CRO location: N13E33
S2187 2013.01.22       S29E07         plage
11662 2013.01.22
2013.01.23
1 1 1 N33E54 0060 HSX HSX location: N28E53

NOAA location way off

S2189 2013.01.23       S18W05         plage
S2191 2013.01.24   1   N14E19 0002   AXX    
S2192 2013.01.24   3   S28W54 0004   BXO    
Total spot count: 20 31 14  
Sunspot number: 60 101 44  (total spot count + 10 * number of spotted regions)
Weighted SN: 40 49 27  (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): 36 35 24 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
2013.01 135.4 (1) 86.9 (2A) / 112.2 (2B) / 68.6 (2C) (56.2 projected, -0.7) (4.18)

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.