Solar Terrestrial Activity Report

Last update issued on July 18, 2003 at 04:10 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 11, 2003)]

Recent activity

The geomagnetic field was unsettled to minor storm on July 17. Solar wind speed ranged between 567 and 771 km/sec, mostly under the influence of a high speed stream from coronal hole CH48.

Solar flux measured at 20h UTC on 2.8 GHz was 138.7. The planetary A index was 22 (STAR Ap - based on the mean of three hour interval ap indices: 22.3).
Three hour interval K indices: 54333344 (planetary), 54344344 (Boulder).

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

At midnight there were 8 spotted regions on the visible disk. Solar flare activity was low. A total of 10 C class events was recorded during the day.

Region 10405 was quiet and stable.
Region 10408 was quiet and stable.
Region 10409 decayed quickly and lost about half of its penumbral area. Flare: C1.1 at 02:46 UTC.
Region 10410 developed quickly and became the largest region on the visible disk. Some polarity intermixing is obvious, and further flux emergence could cause magnetic delta structures to form. An M class flare is possible. Flares: C2.3 at 09:14, C2.6 at 15:29, C1.4 at 16:54, C2.8 at 17:44, C3.8 (associated with a weak to moderate type II radio sweep) at 18:40, C1.3 at 20:13 and C5.1 at 23:56 UTC.
Region 10411 was quiet and stable.
Region 10412 developed further and has a weak magnetic delta structure in the northwestern part. A minor M class flare is possible. Flares: C9.8/1N (M1.0 recorded by GOES10, this event was associated with moderate type II and IV radio sweeps) at 08:23 and C2.2 at 18:22 UTC.
Region 10413 was quiet and stable.
New region 10414 rotated into view at the southeast limb on July 16 and was numbered by SEC the next day.

Coronal mass ejections (CMEs)

July 15-16: No potentially geoeffective CMEs observed.

July 17: There may have been a faint CME associated with the C9 flare in region 10412.

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 recurrent coronal hole (CH48) in the northern hemisphere and with a large trans equatorial extension was in a geoeffective position on July 12-16.

Processed GOES SXI coronal structure image at 22:26 UTC on July 17. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to active on July 18 and quiet to active on July 19 due to a high speed stream from coronal hole CH48. CMEs associated with flares in regions 10410 and 10412 on July 17 could reach Earth on July 20 and cause an increase in geomagnetic activity.

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.]

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
10401 2003.07.06 2   S09W90 0010 AXX rotated out of view
10403 2003.07.07     S16W78     plage
10404 2003.07.07     S11W67     plage
10405 2003.07.11 3 1 S10W16 0020 CSO classification was HSX
at midnight, area 0050
10407 2003.07.11     N10W49     plage
10408 2003.07.13 2 1 N12W31 0020 CSO classification was HRX
at midnight
10409 2003.07.13 45 38 N15E18 0210 EAI beta-gamma
area was 0150
at midnight
10410 2003.07.13 29 43 S12E12 0160 DAC beta-gamma
10411 2003.07.15 1 1 N14E38 0040 HSX area was 0070
at midnight
10412 2003.07.16 15 25 N16E05 0060 DAI beta-gamma-delta
10413 2003.07.16 1 1 N18E35 0020 HSX  
10414 2003.07.17 1 1 S02E71 0090 HAX formerly region S209
S208 emerged on
2003.07.15
    N11W55     plage
Total spot count: 99 111
SSN: 189 191

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)
2003.07 130.5 (1) 75.9 (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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