NOAA/USAF Report of Solar-Geophysical Activity 21 May 2000

Report of Solar-Geophysical Activity

:Issued: 2000 May 21 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 142 ISSUED AT 2200Z ON 21 MAY 2000

IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  20/2100Z

TO 21/2100Z:  SOLAR ACTIVITY REMAINED AT LOW LEVELS. OCCASIONAL

C-CLASS SUBFLARES OCCURRED. REGION 8996 (S21W49) DECREASED IN AREA

BY VIRTUE OF PENUMBRAL DECAY, BUT WAS THE MOST FLARE-PRODUCTIVE OF

THE VISIBLE REGIONS. HOWEVER, REGION 8998 (S12W33) WAS RESPONSIBLE

FOR THE LARGEST FLARE OF THE PERIOD – A C8/SF AT 21/1023Z. THIS

REGION SHOWED NO SIGNIFICANT CHANGE DURING THE PERIOD AND WAS OF

MODERATE SIZE AND MAGNETIC COMPLEXITY. NO SIGNIFICANT CHANGES WERE

REPORTED IN THE REMAINING REGIONS.

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

LOW TO MODERATE LEVELS. OCCASIONAL C-CLASS FLARES ARE EXPECTED.

ISOLATED M-CLASS FLARES ARE POSSIBLE.

IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 20/2100Z TO 21/2100Z:

GEOMAGNETIC FIELD ACTIVITY WAS AT QUIET TO UNSETTLED LEVELS. PROTON

AND ELECTRON FLUXES AT GEOSYNCHRONOUS ORBIT REMAINED AT BACKGROUND

LEVELS.

IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS

EXPECTED TO BE AT QUIET TO UNSETTLED LEVELS DURING MOST OF THE

PERIOD WITH A CHANCE FOR ACTIVE LEVELS ON 23 MAY. PROTON AND

ELECTRON FLUXES AT GEOSYNCHRONOUS ORBIT ARE EXPECTED TO REMAIN AT

BACKGROUND LEVELS.

III.  EVENT PROBABILITIES 22 MAY-24 MAY

CLASS M    60/60/60

CLASS X    10/10/10

PROTON     05/05/05

PCAF       GREEN

IV.  PENTICTON 10.7 CM FLUX

OBSERVED           21 MAY 232

PREDICTED   22 MAY-24 MAY  225/220/215

90 DAY MEAN        21 MAY 196

V.  GEOMAGNETIC A INDICES

OBSERVED AFR/AP 20 MAY  004/006

ESTIMATED AFR/AP 21 MAY  008/008

PREDICTED AFR/AP 22 MAY-24 MAY  008/008-015/010-012/012

VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 22 MAY-24 MAY

A.  MIDDLE LATITUDES

ACTIVE                25/30/25

MINOR STORM           10/15/10

MAJOR-SEVERE STORM    01/01/01

B.  HIGH LATITUDES

ACTIVE                30/35/30

MINOR STORM           15/20/15

MAJOR-SEVERE STORM    01/01/01