Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 9, 2013 at 05:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update February 1, 2013)] [Cycle 24 progress (last update February 2, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update February 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update February 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update February 3, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated February 3, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet on February 8. Solar wind speed at SOHO ranged between 349 and 441 km/s, gradually increasing all day.

Solar flux measured at 20h UTC on 2.8 GHz was 104.2 (decreasing 64.3 over the last solar rotation). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.5). Three hour interval K indices: 12222211 (planetary), 22323301 (Boulder).

The background x-ray flux was at the class B2 level.

At midnight UTC the visible solar disk had 9 spotted active regions (in 2K resolution SDO images).

Region 11665 [N13W69] was quiet and stable.
Region 11667 [N22W23] decayed slowly and quietly.
Region 11669 [N08E15] gained a few trailing penumbra spots.
Region 11670 [N18E15] developed further adding spots and gaining penumbral area. C flares are possible.

Spotted regions not numbered by SWPC:
S2208 [S20W42] reemerged with a penumbra spot.
S2212 [N18W03] was quiet and stable.
New region S2213 [N22E31] emerged with several penumbra spots in an old plage area.
New region S2214 [S17W62] emerged with a few spots.
New region S2215 [S27W12] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

February 7-8: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
February 6: A partial halo CME was observed after a C8 event in AR 11667 early in the day.

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 small coronal hole (CH553) in the southern hemisphere rotated across the central meridian on February 4-5.

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 poor.

Forecast

The geomagnetic field is expected to be quiet to unsettled on February 9 and quiet on February 10-11.

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
11666 2013.01.28
2013.01.29
      S24W76           plage
11665 2013.01.28
2013.01.29
1 1 1 N13W72 0120 HSX HSX area: 0180

location: N13W69

11667 2013.01.31
2013.02.01
4 6 2 N23W25 0080 CSO CSO

location: N22W23

S2208 2013.02.01   1 1 S20W42 0004   AXX   plage
11668 2013.02.02
2013.02.03
      N12W86           plage
11669 2013.02.04
2013.02.05
2 10 3 N07E11 0014 AXX CRO

area: 0022

11670 2013.02.05
2013.02.07
10 32 15 N19E12 0070 DAO DAI area: 0240
S2212 2013.02.06   7 1 N18W03 0012   BXO  
S2213 2013.02.08   5 1 N22E31 0010   BXO    
S2214 2013.02.08   3 2 S17W62 0016   BXO    
S2215 2013.02.08   1   S27W12 0003   AXX    
Total spot count: 17 66 26  
Sunspot number: 57 156 106  (total spot count + 10 * number of spotted regions)
Weighted SN: 32 84 44  (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): 34 55 58 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 57.7 (-1.2) 13.90
2012.08 115.4 63.0 (58.6 projected, +0.9) 7.96
2012.09 122.9 61.4 (58.7 projected, +0.1) 8.07
2012.10 123.3 53.3 (58.1 projected, -0.6) 9.97
2012.11 121.3 61.4 (57.4 projected, -0.7) 7.08
2012.12 108.6 40.8 (56.7 projected, -0.7) 3.44
2013.01 127.1 62.9 (56.0 projected, -0.7) 4.49
2013.02 106.1 (1) 15.1 (2A) / 52.9 (2B) / 49.7 (2C) (55.0 projected, -1.0) (4.64)

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.