NOAA/USAF Report of Solar-Geophysical Activity 6 Apr 2000

:Product: Report of Solar-Geophysical Activity

:Issued: 2000 Apr 06 2200 UT

# Prepared jointly by the U.S. Dept. of Commerce, NOAA,

#Space Environment Center and the U.S. Air Force.

#

JOINT USAF/NOAA REPORT OF SOLAR AND GEOPHYSICAL ACTIVITY

SDF NUMBER 097 ISSUED AT 2200Z ON 06 APR 2000

IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  05/2100Z

TO 06/2100Z:  SOLAR ACTIVITY WAS MODERATE.  REGION 8948 (S12E42)

PRODUCED AN M1/2B FLARE AT 06/0229UT.  THIS EVENT WAS ACCOMPANIED BY

A MINOR RADIO BURST AND A TYPE II SWEEP (ESTIMATE SHOCK VELOCITY OF

700KM/S).    REGION 8948 RETAINS SOME MAGNETIC COMPLEXITY, BUT IT

AND MOST OF THE OTHER 11 SPOTTED REGIONS ON THE DISK APPEAR TO BE

SLOWLY DECLINING.   REGION 8933 (N19W96) HAS QUIETLY ROTATED OFF THE

DISK.  THE SMALL FILAMENT NEAR S15 E10 DISAPPEARED EARLY TODAY.

IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW

TO MODERATE.  RETURNING REGION 8910 (N13 L=069), A MAJOR FLARE

PRODUCER LAST ROTATION,  IS DUE BACK ON THE EAST LIMB LATE TOMORROW.

IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 05/2100Z TO 06/2100Z:

THE GEOMAGNETIC FIELD RANGED FROM UNSETTLED TO MAJOR STORM LEVELS.  A

SHOCK WAS OBSERVED BY THE ACE SPACECRAFT AROUND 06/1600UT.  THE

ASSOCIATED SUDDEN IMPULSE WAS OBSERVED AT  1640UT (37NT AS OBSERVED

AT SAN JUAN) AND THE FIELD HAS BEEN AT MAJOR STORM LEVELS SINCE THAT

TIME.  THERE WERE MAGNETOPAUSE CROSSINGS OBSERVED ON BOTH GOES 8 AND

GOES 10 STARTING AROUND 1800UT.  THIS DISTURBANCE IS MOST LIKELY THE

CONSEQUENCE OF THE HALO CME OBSERVED FOLLOWING THE C9/2F FLARE AT

04/1541UT.  THE SATELLITE PROTON EVENT WHICH BEGAN AT 04/2055UT,

ENDED TODAY AT 0155UT.

IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS

EXPECTED TO BE AT STORM LEVELS FOR MUCH OF TOMORROW.  THE FIELD IS

EXPECTED TO RETURN TO UNSETTLED LEVELS BY THE END OF THE PERIOD.

III.  EVENT PROBABILITIES 07 APR-09 APR

CLASS M    50/50/50

CLASS X    05/05/05

PROTON     05/05/05

PCAF       GREEN

IV.  PENTICTON 10.7 CM FLUX

OBSERVED           06 APR 178

PREDICTED   07 APR-09 APR  175/180/180

90 DAY MEAN        06 APR 185

V.  GEOMAGNETIC A INDICES

OBSERVED AFR/AP 05 APR  014/012

ESTIMATED AFR/AP 06 APR  030/033

PREDICTED AFR/AP 07 APR-09 APR  025/030-010/020-008/015

VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 07 APR-09 APR

A.  MIDDLE LATITUDES

ACTIVE                35/15/15

MINOR STORM           35/10/10

MAJOR-SEVERE STORM    11/01/01

B.  HIGH LATITUDES

ACTIVE                30/40/20

MINOR STORM           40/20/10

MAJOR-SEVERE STORM    06/01/01