Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 29, 2015 at 03:00 UT.

Charts (* = updated daily) Data and archive
  Solar wind (*) Solar and geomagnetic data - last month (*)
  Electron fluence (*) Archived daily reports and monthly data from 2003.01 (May 1, 2015)
Solar cycle Solar cycles 23-24 (May 1, 2015) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (May 1, 2015) Noon SDO sunspot count 1K Reference: 4K (large file) (*)
  Solar cycles 1-20 POES auroral activity level October 2009 - December 2012
  Comparison of cycles 21, 22, 23 and 24 (May 1, 2015) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 10, 12, 13, 14, 16 and 24 (May 1, 2015) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs solar cycles (May 9, 2015)  

Recent activity

The geomagnetic field was quiet on May 28. Solar wind speed at SOHO ranged between 311 and 376 km/s. Solar wind speed increased slowly during the day. Wind temperature indicated the presence of a low speed coronal hole stream, likely from CH670.

Solar flux at 20h UTC on 2.8 GHz was 93.0 (decreasing 6.9 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 126.5. The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.4). Three hour interval K indices: 22122111 (planetary), 32*33312 (Boulder).

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

At the time of counting spots (see image time), spots were observed in 7 active regions using 2K resolution (SN: 94) and 6 active regions using 1K resolution (SN: 70) SDO images on the visible solar disk.

Region 12355 [S10W11] was quiet and stable.
New region 12356 [S17E62] rotated into view on May 27 and was numbered by SWPC the next day.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4502 [S12E50] was quiet and stable.
New region S4510 [S09W68] emerged early in the day with a few pots.
New region S4511 [N08E59] was observed with penumbra spots.
New region S4512 [S17E10] emerged with penumbra spots.
New region S4513 [S09E07] emerged with penumbra spots.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
           

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

Coronal mass ejections (CMEs)

May 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]

A northern hemisphere coronal hole (CH670) rotated across the central meridian on May 24-26.

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 with a chance of unsettled and active intervals on May 29 due to a low speed stream associated with CH670 and quiet on May 30-31.

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 overlays
Comment
SWPC Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12351 2015.05.17
2015.05.19
      N22W79            
12352 2015.05.20
2015.05.22
      N05W78            
S4485 2015.05.20       S08W46            
S4486 2015.05.20       N16W56            
12353 2015.05.21
2015.05.22
      N07W89        

 

S4489 2015.05.21       N19W46            
12354 2015.05.22
2015.05.23
      S19W88          
S4493 2015.05.22       S10W28            
S4494 2015.05.22       N17W55            
12355 2015.05.23
2015.05.24
  3 2 S09W14 0014   BXO location: S10W11
S4498 2015.05.25       N02E11            
S4499 2015.05.25       S19W34            
S4500 2015.05.26       N22W32            
S4501 2015.05.26       N12E40          
S4502 2015.05.26   4 2 S12E50 0008   AXX  
S4505 2015.05.26       N22W02            
S4506 2015.05.26       S23E01            
S4507 2015.05.26       S23W42          
12356 2015.05.27
2015.05.28
1 5 1 S15E61 0060 HAX CAO area: 0090
S4509 2015.05.27       N34W04          
S4510 2015.05.28   3 2 S09W68 0012   CRO    
S4511 2015.05.28   5 2 N08E59 0013   BXO    
S4512 2015.05.28   2 1 S17E10 0006   AXX    
S4513 2015.05.28   2   S09E07 0006   AXX    
Total spot count: 1 24 10  
Sunspot number: 11 94 70  (total spot count + 10 * number of spotted regions)
Weighted SN: 6 32 18  (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): 7 33 39 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
2013.12 147.7 143.1 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) (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 78.5 (-1.2) 4.50
2014.08 124.7 127.9 74.7 75.5 (-3.0) 7.71
2014.09 146.6 148.1 87.6 70.8 (-4.7) 9.78
2014.10 153.4 152.9 60.6 67.3 (-3.5) 8.96
2014.11 154.8 151.4 70.1 (64.9 projected, -2.4) 9.33
2014.12 158.7 153.8 78.0 (62.6 projected, -2.3) 11.24
2015.01 141.9 137.3 67.0 (60.4 projected, -2.2) 9.46
2015.02 129.1 126.0 44.8 (58.7 projected, -1.7) 9.92
2015.03 125.9 124.6 38.4 (56.3 projected, -2.4) 16.14
2015.04 128.8 129.7 54.4 (53.7 projected, -2.6) 10.73
2015.05 (122.8)   80.0 (2A) / 88.6 (2B) / 75.5 (2C) (51.5 projected, -2.2) (8.5)

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.