:Product: Weekly Highlights and Forecasts
:Issued: 2000 Aug 01 2112 UT
HIGHLIGHTS OF SOLAR AND GEOMAGNETIC ACTIVITY
24 - 30 JULY 2000

SOLAR ACTIVITY WAS AT LOW TO HIGH LEVELS. THE PERIOD BEGAN WITH
ACTIVITY AT LOW LEVELS ON 24 JULY. ACTIVITY INCREASED TO HIGH LEVELS
ON 25 JULY AS REGION 9097 (N08, L = 170, CLASS/AREA EKC/510 ON 25
JULY) PRODUCED AN M8/2B AT 25/0249UT WITH ACCOMPANYING TYPE II AND
IV RADIO SWEEPS. AN ASSOCIATED FAINT HALO CME WAS OBSERVED BY LASCO,
BEGINNING AT 25/0300UT. THIS REGION ALSO PRODUCED AN M1/1B AT
25/1846UT. REGION 9087 (S12, L = 235, CLASS/AREA FAC/380 ON 25
JULY),  PRODUCED AN M3/2N FLARE AT 25/0456UT AS IT APPROACHED THE
WEST LIMB. ACTIVITY DROPPED TO MODERATE LEVELS DURING 26 JULY, DUE
TO A SINGLE OPTICALLY UNCORRELATED M1 EVENT, WITH THE MOST LIKELY
SOURCE BEING REGION 9087 BEHIND THE WEST LIMB (S11W94). ACTIVITY
CONTINUED TO BE MODERATE ON 27 AND 28 JULY DUE TO MINOR M-CLASS
FLARES FROM REGION 9090 (N14, L = 203, CLASS/AREA FAI/380 ON 27
JULY). ACTIVITY DECREASED TO LOW LEVELS FOR THE LAST TWO DAYS OF THE
PERIOD.

REAL-TIME SOLAR WIND VELOCITY AND DENSITY DATA WERE AVAILABLE FROM
THE NASA ADVANCED COMPOSITION EXPLORER (ACE) SPACECRAFT FOR MOST OF
THE PERIOD. SOLAR WIND VELOCITIES WERE 315 - 410 KM/SEC DURING THE
PERIOD OF 24 - 27 JULY. TWO WEAK SHOCKS WERE OBSERVED AT ACE AT
26/0254UT AN 26/1756UT. ON 28 JULY VELOCITY RANGED FROM 330-390
KM/SEC UNTIL 28/0543UT WHEN A SHOCK FROM THE 25 JULY CME WAS
OBSERVED. VELOCITY THEN INCREASED TO 450-490 KM/SEC. DENSITY
INCREASED FROM 1-5 P/CC TO 10-36 P/CC. DENSITY DECREASED TO A RANGE
OF 2-10 P/CC AFTER 28/2037UT. IMF BZ AVERAGED -8 NT AND PROCEEDED TO
DECREASE IN THE SOUTHWARD DIRECTION AFTER SHOCK PASSAGE, RANGING
FROM -12 TO -20 NT. AT 28/1741 THE IMF BZ WENT NORTHWARD AND
AVERAGED AROUND +5 NT FOR THE REST OF THE DAY. BY THE END OF THE
PERIOD VELOCITY WAS RANGING FROM 400-470 KM/SEC, DENSITY FROM 1-6
P/CC, AND IMF BZ FROM -4 NT TO +5 NT. IMF BZ WAS PREDOMINATELY
NORTHWARD DURING 29-30 JULY.

A GREATER THAN 10 MEV PROTON FLUX AT GEOSYNCHRONOUS ORBIT EVENT WAS
OBSERVED ON 28 JULY. PARTICLE FLUXES BEGAN TO RISE SLOWLY AFTER
28/0200UT AND ATTAINED THRESHOLD AT 28/1050UT. THE PEAK OF THE EVENT
WAS 18 PFU AT 28/1130UT AND THE EVENT FELL BELOW THRESHOLD AT
28/1310UT.

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT WAS AT
NORMAL TO MODERATE LEVELS THROUGHOUT THE PERIOD.

GEOMAGNETIC FIELD ACTIVITY WAS AT QUIET TO UNSETTLED LEVELS 24 AND 25
JULY. ACTIVITY INCREASED TO QUIET TO MINOR STORM LEVELS ON 26 JULY.
TWO WEAK SHOCK PASSAGES AT APPROXIMATELY 26/0300UT AND 26/1800UT
CONTRIBUTED TO PERIODS OF ACTIVE AND MINOR STORMING LEVELS IN THE
GEOMAGNETIC FIELD. ACTIVITY DECREASED TO QUIET TO UNSETTLED, WITH
ISOLATED ACTIVE PERIODS AT HIGHER LATITUDES ON 27 JULY.  ACTIVITY
INCREASED TO QUIET TO MINOR STORM LEVELS ON 28 JULY DUE TO THE
ARRIVAL OF TRANSIENT MATERIAL FROM THE CME OF 25 JULY. THE FIRST
INDICATION OF THE TRANSIENT WAS A SHOCK AT ACE AT 28/0543UT, SHORTLY
FOLLOWED BY A SUDDEN IMPULSE AT 28/0635UT (MEASURING 41 NT ON THE
BOULDER MAGNETOMETER. MINOR STORM LEVELS (ESTIMATED KP'S OF 5) WERE
SUSTAINED FOR 12 HOURS FROM 28/0600 - 28/1800UT. EFFECTS FROM THE
CME PASSAGE CONTINUED ON INTO 29 JULY WITH PREDOMINATELY ACTIVE TO
MINOR STORM LEVELS, WITH AN ISOLATED PERIOD OF MAJOR STORMING AT
HIGH LATITUDES. BY THE END OF THE DAY, THE GEOMAGNETIC FIELD WAS
QUIET TO UNSETTLED. ACTIVITY CONTINUED TO BE QUIET TO UNSETTLED ON
30 JULY, WITH ISOLATED ACTIVE PERIODS OF LOCAL SUBSTORMING OBSERVED
IN THE NIGHTTIME SECTOR.

FORECAST OF SOLAR AND GEOMAGNETIC ACTIVITY
02 - 28 AUGUST 2000

SOLAR ACTIVITY IS EXPECTED TO BE AT MODERATE TO HIGH LEVELS. ISOLATED
M-CLASS FLARES ARE EXPECTED. THERE IS ALSO A CHANCE FOR ISOLATED
MAJOR FLARES DURING THE PERIOD.

THERE IS A CHANCE FOR A GREATER THAN 10 MEV SOLAR PROTON EVENT AT
GEOSYNCHRONOUS ORBIT DURING THE PERIOD.

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT IS
EXPECTED TO BE AT NORMAL TO MODERATE LEVELS THROUGH MOST OF THE
PERIOD.

GEOMAGNETIC FIELD ACTIVITY IS EXPECTED TO BE AT QUIET TO UNSETTLED
LEVELS DURING THE REST OF THE PERIOD, BARRING AN EARTH-DIRECTED CME.


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