March 31, 2001 geomagnetic storm
Notes to readers not yet familiar with ham radio
by Volker Grassmann, DF5AI, May 14, 2005
Cooperation between research and ham radio
Amateur radio stations are designed for communication purposes rather than scientific measurements. There is however a long history of scientific analyses using amateur radio observations on very high frequencies (see, e.g., , -, ). In fact, amateur radio frequencies are monitored almost permanently by ham operators searching for unusual examples of radiowave propagation (the so-called dx openings). Implicitly, they search for unusual atmospheric phenomena because any dx opening is associated with special geophysical phenomena in the Earth atmosphere. Thus, radio amateurs can provide information on date, time, frequency and the position of many events in the lower, middle (partially) and upper atmosphere. To reveal the nature of Auroral backscatter in the E region of the ionosphere, scientists have therefore cooperated with radio amateurs, in particular between the 1960s and 1980s (note, for example, the scientific origin of the 144 MHz amateur radio beacon OZ7IGY, International Geophysical Year, and SK4MPI, Max Planck Institute which are, by the way, still operational). When satellites and ionospheric radar systems became availabe to the scientists, this cooperation came to an end, more or less.
Since then, amateur radio stations have also increased their technical capabilities considerably. Achievements in antenna, transmitter and receiver design result in higher effective transmitter power and improved system sensitivities, and personal computers support digital processing of radiosignals at low fieldstrengths as well as numerical radio propagation analyses and simulations (see, e.g., , , , ). Various beacon networks, Aurora alert services, email forums and other type of services distribute actual 'radio weather' information around the world by using amateur radio 'infrastructure' or, alternatively, by using the internet, mobile phones and pagers (e.g., , , , ). In Aurora research, ham operators have implemented automatic devices monitoring radio beacon signal variations , have introduced a magnetometer construction kit resulting in a growing number of amateur magnetometer stations (see, e.g., , ) and have realized even their own ionospheric radar system .
The sum of all amateur radio stations may be considered a global observation network which monitors the radio frequency spectrum more or less permanently. Because of the high geographical density of amateur radio stations (in Germany, for example, the density is one station per 10 square kilometers), this observation network covers large geographical areas exceeding the range of ionospheric radar systems considerably. In consequence, European and North American radio amateurs can hardly fail to discover any event of Auroral backscatter occuring south of, say 70 degree northern latitude.
All this achievements and developments result from personal initiatives by many radio amateurs. However, the above mentioned observation network is not identical to scientific, commercial or other types of professional networks, of course. Radio amateurs haven't implemented organizational structures equivalent to weather bureaus and geophysical data centers, we do not analyse the huge amount of observation material on a regular and systematical basis.
On the other hand, calling for data in the internet and in the packet-radio networks reveals a wealth of information contributed by radio amateurs willing to support data analysis projects. This is actually the concept of this project, i.e. studying the signature of the March 31, 2001 geomagnetic storm in VHF long-distance communication by using observation material from the world-wide community of radio amateurs.