Welcome de KL7J, Soldotna - Alaska.
Data has been updated as of .
With an Alaskan northern propagation emphasis in Northern Prop Section.
1). What is happening now, the indexes.
From Space WX : "When Bz is south (Bz -), that is, opposite Earth's magnetic field, the two fields link up," explains Christopher Russell, a Professor of Geophysics and Space Physics at UCLA. "You can then follow a field line from Earth directly into the solar wind" -- or from the solar wind to Earth. South-pointing Bz's open a door through which energy from the solar wind can reach Earth's atmosphere!
Southward Bz's often herald widespread auroras, triggered by solar wind gusts or coronal mass ejections that are able to inject energy into our planet's magnetosphere." [-Bz]. The HF propagation is usually negatively impacted during these events.
2). What might occur or recent history.
Possible storm Pre and Post Enhancements
(Auroral Zone in the center row of chart represents South Central AK)
DX openings at higher MUF's during the increasing ionization before the upset magnetic field impacts the bands, or catch it on the down side with the magnetic field back normal before ionization decreases substantially. This is usually called pre-enhancement or post-enhancement and is somewhat intuitive. There are also paths associated by which month of the year.
Propagation characteristics in the north.
The farther North or South of the equator is significant.
* Central and South-Central Alaska do not get the
higher band openings (MUF) as often or as long *
The daytime F region frequencies peak not at the magnetic equator, but around 15 to 20 degrees north and south of it. This is called the equatorial anomaly. At night, frequencies reach a minimum around 60 degrees latitude north and south of the geomagnetic equator. This is called the mid-latitude trough. Large tilts can occur in the vicinity of these phenomena which may lead to variations in the range of sky waves that have reflection points nearby. Link
Note from The high-latitude ionosphere and its effects on radio propagation by: R.D.Hunsucker, J.K. Hargreaves, 2003.
The low-latitude zone, spanning 20 or 30 deg either side of the magnetic equator, is strongly influenced by electromagnet forces that arise because the geomagnetic field runs horizontally over the magnetic equator. The primary consequence is that the electrical conductivity is abnormally large over the equator…
At high latitudes we find the opposite situation. Here the geomagnetic field runs nearly vertical, and this simple fact of nature leads to the existence of an ionosphere that is considerably more complex than that in either the middle or the low-latitude zones. "This happens because the magnetic field-lines connect the high latitudes to the outer part of the magnetosphere which is driven by the solar wind, whereas the ionosphere at middle latitude is connected to the inner magnetosphere which essentially rotates with the Earth and so is less sensitive to external influence."
The Magnetic North Pole is close to Alaska compared to most.
This geatly impacts propagation on the high and low bands MUF and absorption.
Near polar paths are very impacted.
The MUF for any 1800 mile path can be determined by finding the midpoint (or half-way point) of the path and examining the MUF at that midpoint on the map by finding the labelled MUF contour value. All contours are given in MHz.
For 2400 mile paths, multiply the given contoured MUF values by 1.1. The MUF for the given 4,000 km path is then determined at the midpoint of the desired path.
For longer path lengths, divide the path into equal 1800 mile or 2400 mile segments and compute the MUFs corresponding to the two midpoints that are 900 miles or 1200 miles from each end of the path. Then select the lower of these two MUFs.
This is a K=4 index level according to Univ of Alaska, Geophysical Institute.
Link to other K levels
KL7J - Soldotna, Alaska
kl7j at acsalaska.net