NOAA?USAF Report of Solar-Geophysical Activity 4 Apr 2000

:Product: Report of Solar-Geophysical Activity

:Issued: 2000 Apr 04 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 095 ISSUED AT 2200Z ON 04 APR 2000

IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  03/2100Z

TO 04/2100Z:  SOLAR ACTIVITY WAS MODERATE.  AN M1 FLARE OCCURRED AT

04/0132UT.  THIS EVENT WAS NOT REPORTED BY GROUND BASED

OBSERVATORIES, BUT IS COINCIDENT WITH ACTIVITY FROM REGION 8948

(S15E70) AS SEEN BY THE SOHO SPACECRAFT.  REGION 8948 CONTAINS A CSO

SPOT GROUP AND IS IN THE AREA OF RETURNING REGION 8906.  REGION 8933

(N17W70) PRODUCED A C9/2F FLARE AT 04/1541UT.  THIS EVENT WAS

ACCOMPANIED BY A DSF AND IS PROBABLY THE SOURCE OF THE INCREASE OF

ENERGETIC PARTICLES SEEN AT THE GOES SPACECRAFT STARTING AROUND

04/1700UT.

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

TO MODERATE.  THERE IS A CHANCE OF M FLARES FROM REGIONS 8933, 8936,

AND 8948.  REGION 8910 (N11 L=069) IS DUE TO RETURN TO THE EAST LIMB

ON 7 APRIL AND COULD INCREASE THE LEVEL OF ACTIVITY.

IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 03/2100Z TO 04/2100Z:

THE GEOMAGNETIC FIELD HAS RANGED FROM QUIET TO MAJOR STORM.  A K=6

WAS OBSERVED AT BOULDER FOR THE 0300UT TIME PERIOD.  THE FIELD

RETURNED TO QUIET LEVELS BY 0900UT ONLY TO BECOME ACTIVE AGAIN BY

1500UT.  SOLAR WIND DATA FROM THE ACE SPACECRAFT INDICATE THAT THIS

ACTIVITY WAS ASSOCIATED WITH CHANGES IN THE INTERPLANETARY MAGNETIC

FIELD.  BZ BEGAN THE DAY AROUND -7NT, TURNED POSITIVE (10NT) AROUND

0200UT AND RETURNED NEGATIVE (-7NT) AFTER 1100UT.  FLUXES  OF >10MEV

PROTONS BEGAN TO INCREASE AFTER 04/1700UT, AND REACH 10PFU AT

04/2030UT.  THIS INCREASE IS PROBABLY RELATED TO THE C9 FLARE FROM

REGION 8933 AS REPORTED IN PART 1A.

IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS

EXPECTED TO BE QUIET TO ACTIVE.

III.  EVENT PROBABILITIES 05 APR-07 APR

CLASS M    50/50/50

CLASS X    05/05/05

PROTON     05/05/05

PCAF       GREEN

IV.  PENTICTON 10.7 CM FLUX

OBSERVED           04 APR 207

PREDICTED   05 APR-07 APR  205/200/200

90 DAY MEAN        04 APR 184

V.  GEOMAGNETIC A INDICES

OBSERVED AFR/AP 03 APR  012/012

ESTIMATED AFR/AP 04 APR  022/020

PREDICTED AFR/AP 05 APR-07 APR  010/015-008/012-008/010

VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 05 APR-07 APR

A.  MIDDLE LATITUDES

ACTIVE                25/10/10

MINOR STORM           10/05/05

MAJOR-SEVERE STORM    01/01/01

B.  HIGH LATITUDES

ACTIVE                30/15/15

MINOR STORM           15/05/05

MAJOR-SEVERE STORM    01/01/01