Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 18, 2015 at 07:55 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, 2015)] [Cycle 24 progress (last update February 1, 2015) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update February 1, 2015)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update February 1, 2015)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update February 1, 2015)]

[Noon SDO sunspot count 1K Reference: 4K (large file) (updated daily)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated January 25, 2015]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was quiet to minor storm on February 17. Solar wind speed at SOHO ranged between 338 and 444 km/s.

Solar flux at 20h UTC on 2.8 GHz was 118.5 (decreasing 5.4 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 146.0. The Potsdam WDC planetary A index was 18 (STAR Ap - based on the mean of three hour interval ap indices: 17.8). Three hour interval K indices: 33332245 (planetary), 32343434 (Boulder).

The background x-ray flux is at the class B4 level.

At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 157) and 9 active regions using 1K resolution (SN: 110) SDO images on the visible solar disk.

Region 12282 [N13W52] decayed slowly and quietly.
Region 12284 [N13E06] decayed slowly and quietly.
Region 12285 [S10W39] decayed slowly and quietly.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4211 [S18W37] decayed slowly and quietly.
S4214 [N07W50] decayed slowly and quietly.
S4217 [S08W25] developed slowly and quietly.
New region S4227 [N18E60] emerged near the northeast limb.
New region S4228 [N14E37] emerged with a few spots.
New region S4229 [S08E82] rotated into view.
New region S4230 [S18W53] emerged with penumbra spots.
New region S4231 [N09E56] was observed with penumbra spots.

C2+ flares (GOES):

Magnitude Peak time (UTC) Location AR Comment
         

Coronal mass ejections (CMEs)

February 15-17: No obviously Earth directed CMEs were observed in LASCO 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 northern hemisphere coronal hole (CH654) rotated across the central meridian on February 15-16.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet to active on February 18-19 due to a moderately high speed coronal hole stream and quiet on February 20.

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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% 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 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 Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12282 2015.02.07 7 4 2 N11W51 0170 CAO HAX

location: N13W52

area: 0120

split off from AR S4214

S4206 2015.02.07       S12W52            
S4210 2015.02.10       N09W34            
S4211 2015.02.10   6 1 S18W37 0010   BXO images/AR_S4211_20150217_2345.png images/AR_S4211_20150216_2345.png  
S4214 2015.02.11   3 2 N07W50 0150   HAX  
12283 2015.02.12       N07W81            
S4217 2015.02.12   12 5 S08W25 0025   CRO  
12284 2015.02.12
2015.02.13
1 3 1 N14E04 0000 AXX AXX area: 0010
S4221 2015.02.13       S17E25            
S4222 2015.02.14       S06W09            
12285 2015.02.14
2015.02.15
2 1   S09W29 0010 AXX AXX area: 0002
S4224 2015.02.15       S17E08          
S4226 2015.02.16       N13W09          
S4227 2015.02.17   1 1 N18E60 0005   HRX    
S4228 2015.02.17   5 3 N14E37 0020   CRO    
S4229 2015.02.17   1 1 S08E82 0006   AXX    
S4230 2015.02.17   7 4 S18W43 0020   BXO    
S4231 2015.02.17   4   N09E43 0005   AXX    
Total spot count: 10 47 20  
Sunspot number: 40 157 110  (total spot count + 10 * number of spotted regions)
Weighted SN: 15 66 39  (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): 24 55 61 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO)
Smoothed sunspot number Average ap
(3)
Measured 1 AU
2013.09 102.6 103.7 36.9 73.1 (+4.1) 5.23
2013.10  132.1 131.2 85.6 75.0 (+1.9) 7.71
2013.11  148.3 145.1 77.6 75.4 (+0.4) 5.68
2013.12 147.7 143.1 90.3 76.0 (+0.6) 4.68
2014.01 157.4 152.4 81.8 77.3 (+1.3) 5.44
2014.02 170.3
(cycle peak)
166.3 102.3 (cycle peak) 78.4 (+1.1) 10.70
2014.03 149.9 148.5 91.9 80.8 (+2.4) 4.88
2014.04 143.9 144.8 84.7 81.9 (+1.1)
(likely solar max)
7.88
2014.05 129.7 132.9 75.2 80.5 (-1.4) 5.75
2014.06 122.0 125.8 71.0 79.7 (-0.8) 6.72
2014.07 137.4 141.8 72.5 78.6 (-1.1) 4.50
2014.08 124.7 127.9 74.7 (76.2 projected, -2.4) 7.71
2014.09 146.6 148.1 87.6 (73.0 projected, -3.2) 9.78
2014.10 153.4 152.9 60.6 (70.5 projected, -2.5) 8.96
2014.11 154.8 151.4 70.1 (68.8 projected, -1.7) 9.33
2014.12 158.7 153.8 78.0 (67.7 projected, -1.1) 11.24
2015.01 141.9 137.3 67.0 (66.5 projected, -1.2) 9.46
2015.02 136.0 (1)   50.0 (2A) / 77.2 (2B) / 75.9 (2C) (64.9 projected, -1.6) (9.9)

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 WDC-SILSO 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 GFZ Potsdam WDC ap indices.

This report has been prepared by Jan Alvestad. It is based on the 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.