Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 29, 2015 at 07:35 UT.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update March 1, 2015)] [Cycle 24 progress (last update March 1, 2015) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update March 1, 2015)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update March 1, 2015)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update March 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 March 15, 2015]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was quiet to unsettled on March 28. Solar wind speed at SOHO ranged between 346 and 519 km/s, increasing slowly as a co-rotating interaction region became geoeffective.

Solar flux at 20h UTC on 2.8 GHz was 145.6 (increasing 18.0 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 129.2. The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.6). Three hour interval K indices: 02321223 (planetary), 01422323 (Boulder).

The background x-ray flux is at the class C1 level.

At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 230) and 11 active regions using 1K resolution (SN: 159) SDO images on the visible solar disk.

Region 12303 [N18W75] developed slowly in the trailing spot section.
Region 12305 [S10W23] decayed slowly and was mostly quiet.
Region 12307 [S19W52] was quiet and stable.
Region 12310 [N08E01] decayed slowly and quietly.
Region 12313 [N17E13] decayed slowly and quietly.
Region 12314 [S22E44] was quiet and stable.
New region 12315 [S19W13] emerged on March 23 and was numbered by SWPC 5 days later. The region developed on March 28 as new flux surfaced.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4298 [S11W36] decayed slowly and quietly.
S4311 [S26E11] developed slwoly and quietly.
S4323 [S20E58] developed slowly and quietly.
New region S4324 [N02E52] was observed with penumbra spots.
New region S4325 [S15E18] emerged with a penumbra spot.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
C2.2 05:26   12305 GOES15  
C2.0 08:12   12305 GOES15  
C2.0 12:30 N04W06 12310 GOES15  
C2.4 16:07 N15W69 12303 GOES15  
C2.2 16:48   12310 SDO  
C2.0 18:33   12303 SDO source difficult to determine, simultaneous activity in AR 12307 and 12309

Flare activity according to SDO/EVE/ESP XRS-B proxy

Coronal mass ejections (CMEs)

March 26-28: No obviously Earth directed CMEs were observed.

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]

An extension of the southern polar coronal hole could be associated with a potentially geoeffective co-rotating interaction region. The extension rotated across the central meridian on March 26-28. A recurrent trans equatorial coronal hole (CH661) will rotate into an Earth facing position on March 30-31.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over 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 March 29-30 with a chance of active to minor storm conditions due to a co-rotating interaction region associated with an extension of the southern polar coronal hole. Quiet to unsettled is likely on March 31 - April 1. On April 2-3 a high speed stream associated with CH661 could cause unsettled to active conditions.

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
12303 2015.03.16
2015.03.17
3 10 7 N18W78 0050 DAO DAI area: 0120
12307 2015.03.19
2015.03.22
  3 1 S19W53 0010   AXX  
S4298 2015.03.19   5   S11W36 0006   BXO  
12309 2015.03.20
2015.03.22
4     N15W87 0080 DAO     rotated out of view

actual location: N13W92

12305 2015.03.20
2015.03.21
22 28 12 S08W19 0410 EKI DKO

area: 0570

S4305 2015.03.22       S02W53            
12310 2015.03.22
2015.03.23
  14 5 N04W11 0030   BXO images/AR_12310_20150328_2345.png images/AR_12310_20150327_2345.png

location: N08E01

12312 2015.03.23       N08W02           trailing part of AR 12310
S4308 2015.03.23       N21W54            
12315 2015.03.23
2015.03.28
2 18 11 S19W16 0010 CAO DRI location: S19W13
S4311 2015.03.23   10 2 S26E15 0016   BXO  
12313 2015.03.23
2015.03.24
1 9 4 N17E11 0030 HAX HRX

 

S4313 2015.03.24       S03W39          
S4315 2015.03.24       S10W05            
S4316 2015.03.24       N09W32            
12314 2015.03.25
2015.03.26
  5 2 S21E40 0012   BXO location: S22E44
S4320 2015.03.26       S03E02            
S4321 2015.03.26       S16W12            
S4323 2015.03.27   5 2 S20E58 0023   CRO  
S4324 2015.03.28   2 1 N02E52 0004   AXX    
S4325 2015.03.28   1 1 S15E18 0002   AXX    
Total spot count: 32 110 49  
Sunspot number: 82 230 159  (total spot count + 10 * number of spotted regions)
Weighted SN: 62 134 73  (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): 49 81 87 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
2013.10  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 75.6 (-3.0) 7.71
2014.09 146.6 148.1 87.6 (71.6 projected, -4.0) 9.78
2014.10 153.4 152.9 60.6 (69.2 projected, -2.4) 8.96
2014.11 154.8 151.4 70.1 (67.4 projected, -1.8) 9.33
2014.12 158.7 153.8 78.0 (66.3 projected, -1.1) 11.24
2015.01 141.9 137.3 67.0 (65.1 projected, -1.2) 9.46
2015.02 129.1 126.0 44.8 (63.6 projected, -1.5) 9.92
2015.03 (125.1)   55.9 (2A) / 61.9 (2B) / 60.6 (2C) (61.6 projected, -2.0) (16.5)

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.