rjr@mgweed.UUCP (Bob Roehrig) (03/06/84)
PROPAGATION BULLETIN NR 10 FROM ARRL HEADQUARTERS NEWINGTON CT MARCH 5 1984 TO ALL RADIO AMATEURS THE SOLAR FLUX DROPPED FROM 174 ON FEB 25 TO 120 ON MARCH 4, AS SEVERAL LARGE SUNSPOT GROUPS MOVED OUT OF SIGHT AROUND THE SUN'S WEST LIMB ON THE 4TH. LEAD SPOTS OF THE ACTIVE AREAS RESPONSIBLE FOR THE FLUX RISE OF FEB 7 THROUGH 10 CAME AROUND THE EAST LIMB AND THE RATE OF FLUX DECLINE SLOWED. VALUES ARE EXPECTED TO TURN UPWARD IN THE NEXT FEW DAYS, BUT READINGS ABOVE 140 SEEM UNLIKELY, AND ANOTHER DIP IS DUE AT THE MIDDLE OF THE MONTH. LOW GEOMAGNETIC ACTIVITY AND GENERALLY GOOD PROPAGATION ON ALL DX BANDS ARE EXPECTED BETWEEN MAR 5 AND 9, ALTHOUGH LOWER SOLAR FLUX VALUES WILL REDUCE DX ACTIVITY ON 28 MHZ TO SOME EXTENT. THE IMPROVING POSITION OF THE SUN WILL MINIMIZE THE EFFECT OF LOWER SOLAR FLUX, AND THE /MUF/ WILL BE MOSTLY HIGHER THAN PREDICTED IN THE PROPAGATION CHARTS IN QST FOR FEBRUARY. THE SAME SHOULD APPLY FOR MOST OF THE LATTER HALF OF MARCH, THOUGH MORE DETAILED INFORMATION FOR THAT PERIOD WILL BE GIVEN IN LATER BULLETINS. INCREASED GEOMAGNETIC ACTIVITY AND DEGRADED PROPAGATION IN THE HIGHER LATITUDES ARE EXPECTED AROUND MARCH 10 AND 13 TO 15. RELATIVELY CALM MAGNETIC FIELD CONDITIONS AND GENERALLY GOOD PROPAGATION ARE DUE MAR 169 THROUGH 25 AND 27 TO 29, THOUGH CONDITIONS IN THE NORTHERN HEMISPHERE WILL BEGIN TO SHOW A SEASONAL DECLINE IN LATE MARCH. AMERICAN SUNSPOT NUMBERS FOR FEBRUARY 23 THROUGH 29 WERE BETWEEN 57 AND 124 WITH A MEAN OF 87.9.