QST de W1AW
Propagation Forecast Bulletin 12 ARLP012
From Tad Cook, KT7H
Seattle, WA March 21, 1997
To all radio amateurs
SB PROP ARL ARLP012
ARLP012 Propagation de KT7H
The biggest news this week was that we are at the equinox, and hours of daylight are about equal between the northern and southern hemispheres. Look for improved worldwide conditions on HF bands as we head into spring. Otherwise, there has been no improvement in solar activity, with conditions last week showing no significant change over the previous week. Solar flux and sunspot numbers were only slightly higher, and on four days the solar flux was just slightly above the average of 75 for the previous 90 days.
The outlook for the next few weeks has solar flux remaining in the mid 70s, with a rise in geomagnetic disturbances centered around March 26 and 27. The March 1997 issue of the magazine Scientific American has a remarkable article about the Solar and Heliospheric Observatory (SOHO), which is held in the point where the Earth's and Sun's gravitational pulls are equal, some 1 million miles toward the Sun from Earth. There is an extensive gallery of images from the data transmitted from the satellite on the Web at http://sohowww.nascom.nasa.gov.
Sunspot numbers for March 13 through 19 were 18, 43, 42, 25, 15, 24 and 0, respectively, with a mean of 23.9. The 10.7 cm flux was 74.1, 75.5, 75.8, 75.7, 75.1, 74.3 and 73.7, respectively, with a mean of 74.9. Estimated planetary A indices for the same period were 7, 4, 6, 8, 5, 6, and 4, respectively, with a mean of 5.7.