Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 2, 2012 at 05:05 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-24 (last update June 2, 2012)] [Cycle 24 progress (last update August 2, 2012) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 2, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update June 2, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 1, 2012)]

[POES auroral activity level since October 2009 - updated July 17, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on August 1. Solar wind speed at SOHO ranged between 353 and 404 km/s.

Solar flux measured at 17h UTC on 2.8 GHz was 141.8 (decreasing 7.4 over the last solar rotation, the measurement at 20h UTC was too high compared to other measurements). 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: 11111113 (planetary), 23122212 (Boulder).

The background x-ray flux is at the class B5 level.

At midnight UTC the visible solar disk had 10 spotted active regions (in 2K resolution SDO images).

Region 11528 [N16W55] decayed slowly and quietly.
Region 11529 [S11W48] was quiet and stable.
Region 11530 [S19W38] decayed slowly and was quiet.
Region 11532 [S21W09] decayed slowly and was mostly quiet.
Region 11534 [N18W03] was quiet and stable with only tiny spots.
Region 11535 [N18E37] was mostly unchanged and could produce C flares.
Region 11537 [N12E64] was quiet and stable
Region 11538 [S23E57] developed slowly and was mostly quiet.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
New region S1836 [S23E72] rotated into view with two spots.
New region S1837 [N27E22] emerged with a tiny spot.

Coronal mass ejections (CMEs)

July 30 - August 1: No obviously Earth directed CMEs were observed in LASCO and STEREO 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

No obvious coronal holes are currently in or close to geoeffective positions.

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 August 2. Quiet conditions are likely on August 3-4.

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 higher resolution image) Compare to the previous day's 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
11528 2012.07.22
2012.07.23
1 2 1 N17W56 0010 HRX HRX

 

11527 2012.07.22
2012.07.23
      N27W59           plage
11529 2012.07.22
2012.07.23
1 2 2 S11W50 0040 HSX HSX location: S11W48
11530 2012.07.23
2012.07.24
1 6 1 S18W41 0120 HSX CSO

area: 0200

location: S19W38

11532 2012.07.25
2012.07.26
9 31 16 S19W14 0280 DKO FHO beta-gamma

area: 0400

location: S21W09

11533 2012.07.26
2012.07.27
      S28W49         location: S29W46
11534 2012.07.27
2012.07.28
  14 2 N17W01 0000   BXO location: N18W03
S1827 2012.07.28       N17W40           plage
S1828 2012.07.28       S22W41           merged with AR 11530
11535 2012.07.29
2012.07.30
12 20 11 N18E37 0150 EAI DSI area: 0300
11536 2012.07.30 7     S22W01 0100 EAO       part of AR 11532
S1832 2012.07.30       N21W30         plage
11537 2012.07.31 1 1 1 N12E64 0040 HSX HSX  
11538 2012.07.31 6 9 5 S22E54 0160 DAO DAO area: 0350
S1833 2012.07.31       N15W36         plage
S1834 2012.07.31       N27W48         plage
S1835 2012.07.31       N12E23         plage
S1836 2012.08.01   2 2 S23E72 0020   DRO    
S1837 2012.08.01   1   N27E32 0000   AXX    
Total spot count: 38 88 41  
Sunspot number: 118 188 131  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 81 124 77  (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): 71 66 72 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)
2011.05 95.8 41.6 47.6 (+5.8) 8.94
2011.06 95.8 37.0 53.2 (+5.6) 8.06
2011.07 94.2 43.9 57.2 (+4.0) 8.16
2011.08 101.7 50.6 59.0 (+1.8) 7.26
2011.09 133.8 78.0 59.5 (+0.5) 12.27
2011.10 137.3 88.0 59.9 (+0.4) 8.28
2011.11 153.5 96.7 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 33.1 (67.4 projected, +1.9) 8.81
2012.03 114.7 64.2 (68.1 projected, +0.7) 16.08
2012.04 113.0 55.2 (67.5 projected, -0.6) 10.10
2012.05 121.5 69.0 (65.8 projected, -1.7) 7.06
2012.06 119.6 64.5 (65.0 projected, -0.8) 10.08
2012.07 133.9 66.5 (66.0 projected, +1.0) 14.37
2012.08 141.8 (1) 3.8 (2A) / 118.0 (2B) (68.6 projected, +2.6) (5.38)

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) Month average to date.
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.