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91-10-31.DLY
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1991-10-31
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/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
DAILY SUMMARY OF SOLAR GEOPHYSICAL ACTIVITY
31 OCTOBER, 1991
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
(Based In-Part On SESC Observational Data)
SOLAR AND GEOPHYSICAL ACTIVITY INDICES FOR 31 OCTOBER
-----------------------------------------------------
!!BEGIN!! (1.0) S.T.D. Solar Geophysical Data Broadcast for DAY 304, 10/31/91
10.7 FLUX=231.5 90-AVG=197 SSN=330 BKI=4345 4546 BAI=037
BGND-XRAY=C1.5 FLU1=*.*E*** FLU10=1.0E+06 PKI=4355 3446 PAI=040
BOU-DEV=044,031,059,091,052,071,053,122 DEV-AVG=065 NT SWF=01:001
XRAY-MAX= M1.0 @ 0912UT XRAY-MIN= C1.2 @ 1700UT XRAY-AVG= C2.4
NEUTN-MAX= +000% @ 2325UT NEUTN-MIN= -007% @ 0640UT NEUTN-AVG= -2.8%
PCA-MAX= +2.7DB @ 1730UT PCA-MIN= -0.1DB @ 2315UT PCA-AVG= +0.6DB
BOUTF-MAX=55334NT @ 2337UT BOUTF-MIN=55269NT @ 1737UT BOUTF-AVG=55303NT
GOES7-MAX=P:+174NT@ 1951UT GOES7-MIN=N:-023NT@ 2331UT G7-AVG=+078,+053,+007
GOES6-MAX=P:+202NT@ 2357UT GOES6-MIN=P:-094NT@ 2336UT G6-AVG=+094,-004,+023
FLUXFCST=STD:220,210,205;SESC:225,215,210 BAI/PAI-FCST=035,025,020/040,030,030
KFCST=4556 6654 3356 5554 27DAY-AP=014,020 27DAY-KP=4333 2222 1123 3545
WARNINGS=*MAJFLR;*PROTFLR;*PROTON;*PCA;*GSTRM;*AURMIDWRN;*AURMIDWCH
ALERTS=**MINFLR:M1.0@0912;**MAGSI:15NT@1655;**PROTNENH;**PCAENH
!!END-DATA!!
PLEASE NOTE: It has been determined that the P1 channel on GOES-7 is causing
the erroneous proton flux values at greater than 1 MeV. This
is the lowest energy channel on GOES-7. Controllers are
continuing to investigate the problem to determine if it is
reparable. Proton fluence at greater than 1 MeV will remain
unavailable until further notice.
BRIEF SUMMARY OF EVENTS
-----------------------
Solar activity was moderate today. Another optically uncorrelated class
M1.0 x-ray event was observed at 09:12 UT. Region 6891 (S12W43), 6892
(S19W44) and 6893 (N17W28) produced numerous mid and high level C-class
flares throughout the period.
Region 6891 showed a fairly significant amount of decay over the last 24
hours, but remains large and complex. Although the flares from this region
are now expected to remain mostly within the minor M-class range, there is a
continuing threat for a possible isolated major event from the region.
Another proton flare is still possible. Region 6891 is now moving out of the
high impact zone and should steadily become less geoeffective. However, it
will remain capable of producing prodigous quantities of protons should a
large energetic proton flare erupt.
Region 6893 has continued to show steady growth. This makes the third
straight day of continued growth within the region. It is now capable of
spawning an isolated M-class flare.
The geomagnetic field ranged from unsettled to major storm levels today.
A period of major to severe geomagnetic storming was observed between 06:00
UT and 12:00 UT. However, this activity was mostly confined to the higher
latitude regions. A sudden magnetic impulse of between approximately 15 and
30 gammas was observed at 16:55 UT. This is thought to be the shock from the
class X2.5/3B tenflare of 30 October. Geomagnetic activity has not been as
stormy as was first anticipated. There is evidence to suggest that we may
have passed into a northwardly directed IMF (interplanetary magnetic field).
This may explain the sudden abrupt stabilization of the field which occurred
during the last major flare impact near 29 October. Although this has not
been confirmed, we expect conditions to remain at mostly minor storm levels
over the next 12 to 24 hours. Conditions should gradually stabilize.
Evidence of magnetospheric compression to the geosynchronous orbit was
briefly observed between 23:33 UT and 23:36 UT. Apparently only GOES-6 was
affected by this brief magnetopause crossing.
The satellite proton event which began at 07:45 UT on 30 October
continued to decay today, but was briefly enhanced at the time of the shock
arrival. Thereafter it rapidly decayed well below the event threshold at
17:15 UT.
These proton enhancements which were observed were associated with weak
PCA events which lasted only a few hours. Complete GIF image plots of the
proton and PCA event, as well as image plots of the IP shock (in addition to
the regular solar GIF images) are available for FTP.
Auroral activity was mostly moderate over the high latitude regions, and
low to moderate over the middle latitude regions. It was significantly
quieter than it has been over the last 48 hours. However, after the arrival
of the interplanetary shock, activity intensified to mostly moderate to high
levels over the high latitude regions. We do not anticipate activity to
become intense enough to be observed over the low latitude regions, although
the Low Latitude Auroral Activity Watch will remain in effect for the next 24
hours. By 02 November, auroral activity should have stabilized to more
dormant levels.
HF propagation conditions were varied today. Prior to the shock
arrival, many middle latitude reports of normal propagation conditions were
received. However, this was confined to the middle and low latitude signal
paths. High and polar latitude signal paths were strongly degraded due to
geomagnetic storming and PCA activity. PCA activity peaked at 17:30 UT
during which time polar path signals were almost completely blacked out.
However, PCA quickly returned to background levels as the proton flux rapidly
declined below the event threshold. Protons are currently enhanced, but are
below the event threshold.
** End of Daily Update **