ARRL

ARRL Propagation Bulletin ARLP005 (1996)

SB PROP @ ARL $ARLP005
ARLP005 Propagation de KT7H

ZCZC AP26
QST de W1AW
Propagation Forecast Bulletin 5  ARLP005
From Tad Cook, KT7H
Seattle, WA  February 3, 1996
To all radio amateurs

SB PROP ARL ARLP005
ARLP005 Propagation de KT7H

This bulletin was delayed by one day due to a delay in getting
solar data.

Solar activity is still very low.  We are very close to the solar
minimum.  The latest projections show the 10.7 cm solar flux
reaching minimum around a year from now, during January and
February 1997.  But similar projections show the sunspot number
reaching minimum during April through June of this year, and a big
increase starting late in 1997.  The sunspot number is derived by
counting visible dark spots on the Sun and factoring in their area.
Solar flux is derived by measuring 10.7 cm radiation from the Sun,
and this seems to correlate with density of ionization in the
ionosphere.

The most disturbed day over the past week was January 29, when the
A index reached 18, and the K index was as high as five.  Otherwise
geomagnetic conditions were quiet over this period.  Solar flux
should head down toward 70 by a week from now and then back above
the mid-seventies late in the month.

Chuck Sherman writes that he found a good source of historical
solar data on the internet via ftp at ftp://ftp.ngdc.noaa.gov/STP/.

Some versions of last week's bulletin ARLP004 had a wrong email
address for the author of this bulletin.  The correct address is
tad@ssc.com.

Sunspot Numbers for January 25 through 31 were 11, 11, 11, 11, 12,
26 and 14, with a mean of 13.7.  10.7 cm flux was 73.9, 73.8, 73.8,
73.6, 74, 74.7 and 76.7, with a mean of 74.4.
NNNN
/EX