Last major update issued on May 24, 2014 at 06:30 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update May 1, 2014)] [Cycle 24 progress (last update May 1, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update May 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update May 1, 2014)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update May 1, 2014)]
[POES auroral activity level October
2009 - December 2012]
[Solar polar fields vs solar cycles - updated April 17, 2014]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]
The geomagnetic field was quiet to minor storm on May 23. Solar wind speed at SOHO ranged between 344 and 556 km/s. A disturbance arrived near 05h UTC, however, early on the interplanetary magnetic field was northwards. From 14:30 to 21:30 the IMF was moderately southwards and this caused a significant increase in geomagnetic activity with active and minor storm conditions recorded towards the end of the day. At the onset of the disturbance solar wind speed increased quickly while density decreased.
Solar flux at 20h UTC on 2.8 GHz was 116.3 (decreasing 4.4 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 146.8. The Potsdam WDC planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 16.3). Three hour interval K indices: 32101345 (planetary), 43112434 (Boulder).
The background x-ray flux is at the class B3 level.
At the time of counting spots (see image time), spots were observed in 13 active regions in 2K resolution (SN: 231) and 9 active regions in 1K resolution (SN: 146) SDO images on the visible solar disk.
Region 12061 [S24W86] was quiet and stable.
Region 12065 [S17W45] developed significantly and a small magnetic delta structure has formed in the northernmost penumbra. Further C class flaring is likely and there is a chance of a minor M class event.
Region 12069 [S17W13] reemerged with a penumbra spot.
Region 12071 [S11E23] gained spots and was quiet.
Region 12072 [S18W30] was quiet and stable.
Region 12073 [S10E37] was quiet and stable.
New region 12074 [S13W33] emerged on May 22 and developed further on May 23 when it was numbered by SWPC.
New region 12075 [S10E78] rotated into view.
Spotted regions not numbered (or interpreted differently) by SWPC:
S3444 [S24W06] reemerged with a penumbra spot.
S3446 [N03W37] reemerged with a penumbra spot.
S3460 [S12E43] developed further and could produce C flares.
S3461 [S18W53] decayed slowly and quietly.
New region S3462 [N24W29] emerged with a penumbra spot.
May 21-23: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
Coronal hole history (since October
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A small trans equatorial coronal hole (CH618) was in an Earth facing position on May 21.
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 fair to good.
The geomagnetic field is expected to be quiet to unsettled on May 24 and quiet on May 25-26.
|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
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.
(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
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with magnetic polarity overlay
SWPC has essentially duplicated the location of AR 12074, correct location: S18W30
SWPC incorrectly includes new region S3460 in 12073
|Total spot count:||42||101||56|
|Sunspot number:||112||231||146||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||70||132||87||(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):||67||81||80||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)|
|Month||Average solar flux||International sunspot number
|Smoothed sunspot number||Average ap
|2013.11||148.3||145.1||77.6||(75.6 projected, +0.6)||5.68|
|2013.12||147.7||143.1||90.3||(76.6 projected, +1.0)||4.68|
|2014.01||157.4||152.4||82.0||(77.6 projected, +1.0)||5.44|
|166.3||102.8 (cycle peak)||(77.4 projected, -0.2)||10.70|
|2014.03||149.9||148.5||92.2||(77.9 projected, +0.5)||4.88|
|2014.04||143.9||144.8||84.7||(77.0 projected, -0.9)||7.88|
|2014.05||137.8 (1)||93.8 (2A) / 126.4 (2B) / 95.6 (2C)||(74.4 projected, -2.6)||(6.3)|
1) Running average based on the daily 20:00 UTC observed solar flux value at
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.