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91-10-25.DLY
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1991-10-26
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/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
DAILY SUMMARY OF SOLAR GEOPHYSICAL ACTIVITY
25 OCTOBER, 1991
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
(Based In-Part On SESC Observational Data)
SOLAR AND GEOPHYSICAL ACTIVITY INDICES FOR 25 OCTOBER
-----------------------------------------------------
!!BEGIN!! (1.0) S.T.D. Solar Geophysical Data Broadcast for DAY 298, 10/25/91
10.7 FLUX=240 90-AVG=195 SSN=249 BKI=4434 4433 BAI=022
BGND-XRAY=C3.3 FLU1=*.*E*** FLU10=7.4E+03 PKI=4433 4544 PAI=028
BOU-DEV=046,048,029,064,066,058,033,031 DEV-AVG=046 NT SWF=03:118
XRAY-MAX= M1.6 @ 1129UT XRAY-MIN= C2.1 @ 2323UT XRAY-AVG= C5.9
NEUTN-MAX= +003% @ 1825UT NEUTN-MIN= -003% @ 2150UT NEUTN-AVG= +0.2%
PCA-MAX= +0.3DB @ 0135UT PCA-MIN= -0.2DB @ 2355UT PCA-AVG= +0.0DB
BOUTF-MAX=55327NT @ 0440UT BOUTF-MIN=55237NT @ 1842UT BOUTF-AVG=55291NT
GOES7-MAX=E:+142NT@ 0418UT GOES7-MIN=N:-055NT@ 1014UT G7-AVG=+063,+062,+007
GOES6-MAX=P:+118NT@ 2306UT GOES6-MIN=E:-036NT@ 0340UT G6-AVG=+073,-001,+021
FLUXFCST=STD:248,255,260;SESC:250,260,265 BAI/PAI-FCST=010,015,015/020,020,020
KFCST=2234 3222 2234 3444 27DAY-AP=013,023 27DAY-KP=2213 4433 3444 4433
WARNINGS=*MAJFLR;*PROTFLR;*PROTON;*PCA;*AURMIDWCH
ALERTS=**MINFLR:M1.2@0759;**MINFLR:M1.6@1129;**MINFLR:M1.3@1738;
**245STRM:0020-2100UT
!!END-DATA!!
BRIEF SUMMARY OF EVENTS
-----------------------
Solar activity was moderate today. Three M-class flares were observed
from Region 6891 (S11E34). Almost all of them were long-duration events.
Region 6891 is the focal point of attention. It remains very complex with a
large naked-eye spot completely encompassed by penumbra and bright plage. It
is a formidable region which will certainly generate at least minor M-class
flares into the forseeable future. Another major flare (possibly an
additional X-class event) is also likely to be observed from this region over
the next 72 hours.
Region 6891 is now capable of producing moderate to high terrestrial
impacts should a geoeffective flare erupt. There is also a moderate risk for
proton activity associated with possible future major flaring. A Potential
Polar Cap Absorption Event Warning has been issued. If a sufficiently
powerful solar proton flare erupts from this region, proton fluence and
energies could become high enough to produce PCA effects over the polar
and high latitude regions. Polar and high latitude radio communicators are
warned to be alert for the potential development of PCA related signal
anomalies for approximately the next 10 days.
Region 6892 (S20E35), which is positioned just to the south of Region
6891, grew substantially in white-light, H-alpha and magnetic aspects. This
region was responsible for one of todays M-class events (an M1.2/SF at 07:59
UT). This region is also a good candidate for future minor M-class flares.
Also, interaction between Region 6891 and 6892 may become increasingly
important if growth continues.
The geomagnetic field was mostly unsettled to active today. High
latitudes witnessed a brief period of minor storming. The perturbations over
the middle latitudes were less severe. Another small coronal hole could
enhance activity during the 27-28 October time frame. None of the flares
observed to date are expected to have a terrestrial impact. However, a
threat does exist for possible flare-induced terrestrial activity over the
next week as Region 6891 approaches the central meridian and moves into the
western solar hemisphere.
HF propagation conditions have been normal to slightly below normal.
Daytime propagation conditions were degraded quite frequently due to minor
solar flares and sustained high x-ray levels. X-rays have been near or above
the class C6.0 level for much of the day. Daytime propagation conditions are
expected to remain approximately normal to below normal over the next 24
hours. The threat for a moderate to high intensity SID/SWF during the
daylight hours exists should Region 6891 spawn another major solar flare.
** End of Daily Update **