Solar Terrestrial Activity Report

Last update issued on July 21, 2003 at 03:50 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update July 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update July 2, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update July 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update April 13, 2003)]
[Archived reports (last update July 21, 2003)]

Recent activity

The geomagnetic field was unsettled to minor storm on July 20. Solar wind speed ranged between 562 and 867.

Solar flux measured at 20h UTC on 2.8 GHz was 157.3. The planetary A index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 20.0).
Three hour interval K indices: 54433333 (planetary), 54433323 (Boulder).

The background x-ray flux is at the class B8 level.

At midnight there were 11 spotted regions on the visible disk. Solar flare activity was low. A total of 23 C class events was recorded during the day.

Region 10405 decayed and could soon become spotless..
Region 10409 decayed slowly and quietly.
Region 10410 developed further and became even more compact. Most of the spots are inside a single extremely large penumbra. There is a magnetic delta structure in the southeastern part of the region. A major flare is possible anytime over the next few days. Flares: C1.8 at 00:30, C2.8 at 01:15, C1.4 at 03:16, C3.9 at 03:56, C1.1 at 04:39, C1.2 at 05:23, C1.4 at 06:25, C2.5 at 08:23, C2.4 at 10:02, C1.7 at 11:55, C2.1 at 12:06, C3.7 at 14:52, C1.8 at 15:54, C5.6 at 16:08, C3.7 at 16:47, C3.9 at 17:26, C3.6 at 17:58, C3.1 at 18:11, C4.4 at 19:11, C2.7 at 21:08 and C1.6 at 23:41 UTC.
Region 10411 was quiet and stable.
Region 10412 decayed but could still produce a minor M class flare.
Region 10413 was quiet and stable but could become spotless today or tomorrow.
Region 10414 was generally unchanged and quiet.
Region 10415 decayed in the leading spot section while some new spots emerged scattered throughout the region.
New region 10416 emerged in the southwest quadrant on July 19 and developed slowly on July 20.
New region 10417 emerged in the southwest quadrant to the southwest of region 10410 on July 19 and developed very quickly on July 20. There may be a magnetic delta structure in the trailing spot section and possibly even in the most northern penumbra. Flare: C2.0 at 08:36 UTC.
New region 10418 emerged on July 18 in the southeast quadrant and was noticed by SEC two days later. The region developed slowly on July 20.

Coronal mass ejections (CMEs)

July 19: A faint partial halo CME was observed in LASCO C3 images early in the day following an event in region 10412. The CME was observed over the west limbs and some of the east limbs.

July 18 and 20: No potentially geoeffective CMEs observed.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A large coronal hole (CH49) in the southern hemisphere will likely be in a geoeffective position on July 24-27, a thin western extension could be in a geoeffective position on July 22.

Processed GOES SXI coronal structure image at 23:54 UTC on July 20. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on July 21-23.

Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay (noted early on, the listening session then had to be aborted because of an approaching thunderstorm)]

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

1) Effects from a coronal hole could reach Earth within the next 5 days.
2) Material from a CME is likely to impact 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 (Recent map)

Compare to the previous day's image.

Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. 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 SEC or where SEC has observed no spots.

Solar region Date numbered SEC
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10405 2003.07.11 1 1 S11W57 0020 HSX  
10407 2003.07.11     N10W88     plage
10408 2003.07.13     N13W71     plage
10409 2003.07.13 15 20 N15W22 0160 DAO  
10410 2003.07.13 44 55 S12W26 0620 EAC beta-gamma-delta
classification was EKC
at midnight, area 1150
10411 2003.07.15 1 1 N17W03 0030 HSX area was 0070
at midnight
location was N14W03
SEC has the same
data for both region
10411 and 10413
10412 2003.07.16 14 17 N16W34 0200 DSI beta-gamma
classification was DAI
at midnight, area 0260
10413 2003.07.16 1 1 N17W03 0040 HSX classification was HRX
at midnight, area 0010
location was N20W06
see comment for
region 10411
10414 2003.07.17 1 1 S02E32 0130 HSX  
10415 2003.07.19 9 16 N13E16 0110 DSO  
10416 2003.07.20 4 6 S09W42 0030 DSO formerly region S212
area was 0060
at midnight
10417 2003.07.20 21 30 S22W36 0110 DSO beta-gamma-delta?
formerly region S213
classification was DAI
at midnight, area 0220
10418 2003.07.20 3 5 S05W08 0020 CSO formerly region S211
classification was CAO
at midnight, area 0040
S208 emerged on
2003.07.15
    N11W81     plage
Total spot count: 114 153
SSN: 224 263

Monthly solar cycle data

Month Average solar
flux at Earth
International sunspot number Smoothed sunspot number
2000.04 184.2 125.5 120.8
cycle 23 sunspot max.
2000.07 202.3 170.1 119.8
2001.12 235.1 132.2 114.6 (-0.9)
2002.06 148.7 88.3 106.2 (-2.6)
2002.07 173.5 99.6 102.7 (-3.5)
2002.08 183.6 116.4 98.7 (-4.0)
2002.09 175.8 109.6 94.6 (-4.1)
2002.10 167.0 97.5 90.5 (-4.1)
2002.11 168.7 95.5 85.2 (-5.3)
2002.12 157.2 80.8 82.0 (-3.2)
2003.01 144.0 79.7 (79.7 predicted, -2.3)
2003.02 124.5 46.0 (74.7 predicted, -5.0)
2003.03 131.4 61.1 (69.0 predicted, -5.7)
2003.04 126.4 60.0 (64.1 predicted, -4.9)
2003.05 115.7 55.2 (59.2 predicted, -4.9)
2003.06 129.3 77.4 (55.2 predicted, -4.0)
2003.07 133.0 (1) 95.1 (2) (51.6 predicted, -3.6)

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically 30-50% less.

This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.


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