FROM SPACE ENVIRONMENT SERVICES CENTER, BOULDER, COLORADO
SDF NUMBER 352
JOINT USAF/NOAA REPORT OF SOLAR AND GEOPHYSICAL ACTIVITY.
ISSUED 2200Z 17 DEC 1988
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM 16/2100Z
TO 17/2100Z:  SOLAR ACTIVITY WAS MODERATE. REGION 5278 (N27E18)
CONTINUES TO BE IMPRESSIVE IN STRUCTURE, MAINTAINING A STRONG
DELTA MAGNETIC CONFIGURATION. IT PRODUCED TWO M-CLASS EVENTS
DURING THE PERIOD: THE FIRST WAS AN M3/SF FLARE AT 17/0502Z
ACCOMPANIED BY SIGNIFICANT DISCRETE RADIO BURSTS (INCLUDING A
280 SOLAR FLUX UNIT TENFLARE), A STRONG TYPE II SWEEP BURST, AND
A TYPE IV SWEEP; THE SECOND WAS AN M2/SF FLARE AT 17/0542Z WITH
MINOR RADIO EMISSIONS. REGION 5273 (S31W34) PRODUCED AN M2/SN
FLARE AT 17/0348Z. REGION 5272 (S11W43) PRODUCED AN M1/1B FLARE
AT 17/1750Z. THE SOLAR MAXIMUM MISSION SATELLITE OBSERVED A
LARGE CORONAL MASS EJECTION FROM THE EAST LIMB. THE CME WAS
FIRST OBSERVED AT 16/0830Z, WHICH COINCIDES WITH THE X4 FLARE
THAT OCCURRED NEAR THAT TIME. IT EXCEEDED 100 DEGRESS IN EXTENT
AND HAD A VELOCITY IN EXCESS OF 1500 KM SEC-1. NO NEW REGIONS
WERE ASSIGNED DURING THE PERIOD.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE
MODERATE TO HIGH. REGION 5278 REMAINS THE PRIMARY THREAT FOR
M-CLASS AND GREATER FLARES. REGIONS 5272, 5273, 5279 (N23W14),
AND 5280 (N26E32) ARE ALSO CAPABLE OF MODERATE ACTIVITY.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 16/2100Z TO 17/2100Z:
THE GEOMAGNETIC FIELD HAS BEEN AT QUIET TO MINOR STORM
LEVELS FOR THE PAST 24 HOURS. A SUDDEN IMPULSE OF
15 NANOTESLAS OCCURRED AT 17/1824Z AND IS MOST LIKELY A
MANEFESTATION OF THE X4 FLARE THAT OCCURRED ON 16 DECEMBER.
A GREATER THAN 10 MEV PROTON EVENT BEGAN AT 17/0610Z, REACHED
A MAXIMUM OF 18 PFU AT 17/0855Z, AND ENDED AT 17/1440Z. THE
MAXIMUM POLAR CAP ABSORPTION ASSOCIATED WITH THIS EVENT WAS
0.6 DECIBELS. A SECOND GREATER THAN 10 MEV PROTON EVENT BEGAN
AT 17/2000Z AND IS CURRENTLY IN PROGRESS. INDICATIONS ARE
THAT THE PRESENT EVENT WILL BE SIMILAR IN MAGNITUDE TO THE
PRECEEDING PROTON EVENT.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE AT MINOR STORM LEVELS DURING THE FIRST DAY OF
THE PERIOD DECLINING TO ACTIVE LEVELS DURING THE REMAINDER OF
THE PERIOD. THIS ACTIVITY IS EXPECTED IN RESPONSE TO THE X4
FLARE OF 16 DECEMBER. THE CURRENT GREATER THAN 10 MEV PROTON
EVENT IS EXPECTED TO END SOMETIME DURING THE NEXT 24 HOURS.
III.  EVENT PROBABILITIES 18 DEC-20 DEC
CLASS M    90/90/90
CLASS X    40/40/40
PROTON     40/40/40
PCAF       YELLOW
IV.  OTTAWA 10.7 CM FLUX
OBSERVED           17 DEC  250
PREDICTED   18 DEC-20 DEC  258/262/262
90 DAY MEAN        17 DEC  167
V.  GEOMAGNETIC A INDICES
OBSERVED  AFR/AP 16 DEC  018/021
ESTIMATED AFR/AP 17 DEC  023/028
PREDICTED AFR/AP 18 DEC-20 DEC  035/035-020/020-018/018