Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 2, 2012 at 05:45 UTC.

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

[POES auroral activity level since October 2009 - updated February 27, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2118 [December 2011 - January 2012] - 2119 [January-February 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to active on March 1. Solar wind speed ranged between 399 and 499 km/s. A high speed stream associated with CH503 was observed arriving at SOHO near 02h UTC and caused unsettled to active conditions for the remainder of the day.

Solar flux measured at 20h UTC on 2.8 GHz was 103.4 (decreasing 7.7 over the last solar rotation). The planetary A index was 15 (STAR Ap - based on the mean of three hour interval ap indices: 15.1). Three hour interval K indices: 04343243 (planetary), 04343233 (Boulder).

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

At midnight UTC the visible solar disk had 5 spotted active regions (in 2K resolution SDO images).

Region 11423 [N16W22] was mostly quiet and stable. Flare: C3.3/1F at 15:26 UTC
New region 11427 [N15W02] emerged in the northeast quadrant on February 29 and was numbered the next day by SWPC. The region has polarity intermixing and could become interesting if it develops further. C flares are possible.

Spotted regions not reported by NOAA/SWPC:
[S1502] emerged in the southwest quadrant on February 29. Location at midnight: S27W29
[S1503] emerged in the northeast quadrant on March 1. Location at midnight: N12E20
[S1504] emerged in the northeast quadrant on March 1. Location at midnight: N10E16

Coronal mass ejections (CMEs)

February 28-March 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

A recurrent coronal hole (CH503) in the northern hemisphere was in an Earth facing position on February 26-27. A coronal hole (CH505) in the southern hemisphere was in an Earth facing position on Feb.29-March 1. A recurrent, elongated coronal hole (CH506) in the southern hemisphere willlikely rotate into an Earth facing position on March 3-4.

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 good.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 2 due to effects from CH503, possibly with active intervals. Quiet to unsettled is likely on March 3-4 as CH505 becomes geoeffective.

Coronal holes (1) Coronal mass ejections (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
S1490 2012.02.22       S20W54           plage
11423 2012.02.22
2012.02.23
1 3 1 N17W21 0090 HSX CSO

area: 0160

11425 2012.02.23
2012.02.26
      N22W34         plage
11424 2012.02.24       N07W13           plage
S1494 2012.02.24       N15W08           plage
S1495 2012.02.25       S20W38           plage
11426 2012.02.26       N11W47         plage
S1496 2012.02.27       N10W00         plage
S1497 2012.02.27       N07W22           plage
S1498 2012.02.28       N33E05           plage
S1499 2012.02.28       S18W51           plage
S1500 2012.02.29       N10E51         plage
11427 2012.02.29
2012.03.01
3 10 7 N15W01 0020 CRO DAI beta-gamma

area: 0070

S1502 2012.02.29   2   S27W29 0000   AXX  
S1503 2012.03.01   1   N12E20 0000   AXX    
S1504 2012.03.01   2 1 N10E16 0010   BXO    
Total spot count: 4 18 9  
Sunspot number: 24 68 39  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 12 28 19  (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): 14 24 21 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) 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)
2008.07 65.7 (SF minimum) 0.5 2.8 (-0.4)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
3.25
2010.12 84.2 14.4 28.8 (+2.3) 3.41 / 4.35
2011.01 83.6 19.1 31.0 (+2.2) 4.32 / 5.51
2011.02 94.6 29.4 33.4 (+2.4) 5.41 / 6.44
2011.03 115.0 56.2 36.9 (+3.5) 7.79 / 8.18
2011.04 112.6 54.4 41.8 (+4.9) 9.71 / 8.83
2011.05 95.8 41.6 47.6 (+5.8) 9.18 / 8.94
2011.06 95.8 37.0 53.2 (+5.6) 8.96 / 8.06
2011.07 94.2 43.9 57.2 (+4.0) 9.14 / 8.16
2011.08 101.7 50.6 59.0 (+1.8) 8.16 / 7.26
2011.09 133.8 78.0 (59.2 projected, +0.2) 12.80 / 12.27
2011.10 137.3 88.0 (59.4 projected, +0.2) 7.52 / 8.28
2011.11 153.5 96.7 (60.8 projected, +1.4) 4.58 / 5.55
2011.12 141.3 73.0 (63.6 projected, +2.8) 3.32
2012.01 132.5 58.3 (67.1 projected, +3.5) 6.59
2012.02 106.5 33.1 (71.0 projected, +3.9) 8.09
2012.03 103.4 (1) 0.8 (2A) / 24.0 (2B) (73.2 projected, +2.2) (15.12)

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 preliminary daily SWPC ap indices. Values in red are based on the official NGDC 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.