NOAA/USAF Report of Solar-Geophysical Activity 18 July 2000
:Product: Report of Solar-Geophysical Activity :Issued: 2000 Jul 19 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 201 ISSUED AT 2200Z ON 19 JUL 2000 IA. ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM 18/2100Z TO 19/2100Z: SOLAR ACTIVITY BECAME HIGH. REGION 9087 (S12W00) PRODUCED A LONG DURATION M6/3N FLARE AT 19/0726Z. MINOR RADIO BURSTS, INCLUDING A WEAK TYPE IV, ACCOMPANIED THIS EVENT. NO CORONAGRAPH DATA WERE AVAILABLE FROM SOHO BUT IT IS ASSUMED THAT THERE WAS A SIGNIFICANT MASS EJECTION WITH THIS EVENT BECAUSE OF SOFT X-RAY DURATION AND INTERPLANETARY PARTICLE FLUXES. REGION 9087 CONTINUED TO EMERGE RAPIDLY IN ITS NEW LEADER AREA AND TO THE SOUTH OF THE PREEXISTING SPOTS. THE DELTA CONFIGURATION REMAINED. REGION 9097 (N05E67) SHOWED ITSELF AS A MODERATELY LARGE CLASS D SUNSPOT REGION AND PRODUCED OCCASIONAL SUBFLARES. REGION 9077 (N19W72) CONTINUED TO DECLINE AND PRODUCED ONLY INFREQUENT SUBFLARES. IB. SOLAR ACTIVITY FORECAST: SOLAR ACTIVITY IS EXPECTED TO BECOME GENERALLY HIGH. THE CONTINUED GROWTH IN AREA AND MAGNETIC COMPLEXITY IN REGION 9087 MAKES IT THE PRIME CANDIDATE FOR A MAJOR EVENT. LESSER FLARES MAY COME FROM REGIONS 9077 AND 9097. IIA. GEOPHYSICAL ACTIVITY SUMMARY 18/2100Z TO 19/2100Z: THE GEOMAGNETIC FIELD WAS QUIET TO UNSETTLED FOR MOST OF THE PERIOD. A SHOCK WAS OBSERVED AT ACE AT 19/1450Z AND A SUDDEN IMPULSE WAS OBSERVED AT THE EARTH AT 19/1526Z. UNSETTLED TO ACTIVE CONDITIONS FOLLOWED THE SHOCK PASSAGE. SOLAR WIND VELOCITY JUMPED FROM APPROXIMATELY 450 KM/S TO OVER 600 KM/S. THE LIKELY SOURCE OF THIS DISTURBANCE WAS A MASS EJECTION ON 17 JULY THAT APPEARED TO BE DIRECTED OFF THE EAST LIMB OF THE SUN. THE GREATER THAN 10 MEV FLUX BEGAN THE PERIOD NEAR 20 PFU AND DECAYED TO NEAR 10 PFU AT THE END OF THE PERIOD. A SLIGHT INCREASE IN FLUX WAS OBSERVED AROUND 19/1500Z WHICH MAY HAVE BEEN RELATED TO THE M6 FLARE MENTIONED ABOVE. IIB. GEOPHYSICAL ACTIVITY FORECAST: THE GEOMAGNETIC FIELD SHOULD RANGE BETWEEN QUIET AND ACTIVE LEVELS FOR 20 JULY. ACTIVE TO MAJOR STORM LEVELS ARE EXPECTED ON 21 JULY IN RESPONSE TO TODAY'S SUSPECTED MASS EJECTION. UNSETTLED TO ACTIVE LEVELS SHOULD RETURN ON 22 JULY. THE CURRENT SOLAR PROTON EVENT COULD END ON 20 JULY. HOWEVER, THE LARGE FLARES EXPECTED FROM REGION 9087 WILL LIKELY CAUSE NEW INJECTIONS OF ENERGETIC PROTONS DURING THE PERIOD. III. EVENT PROBABILITIES 20 JUL-22 JUL CLASS M 90/90/90 CLASS X 50/50/50 PROTON 50/50/50 PCAF YELLOW IV. PENTICTON 10.7 CM FLUX OBSERVED 19 JUL 250 PREDICTED 20 JUL-22 JUL 252/245/235 90 DAY MEAN 19 JUL 188 V. GEOMAGNETIC A INDICES OBSERVED AFR/AP 18 JUL 008/013 ESTIMATED AFR/AP 19 JUL 012/014 PREDICTED AFR/AP 20 JUL-22 JUL 020/015-050/040-020/015 VI. GEOMAGNETIC ACTIVITY PROBABILITIES 20 JUL-22 JUL A. MIDDLE LATITUDES ACTIVE 40/25/40 MINOR STORM 15/25/15 MAJOR-SEVERE STORM 10/30/10 B. HIGH LATITUDES ACTIVE 40/25/40 MINOR STORM 15/25/15 MAJOR-SEVERE STORM 10/30/10
