Space Weather Page

Posted by James Watson on 29 Aug, 2016

A 'space weather' page has been added to the proppy site to display the content NOAA's wwv.txt reports in a graphical format. The page also includes a few links to external resources describing space weather and the indices by which it's characterised in a little more detail. Ian Poole's article is highly recommend as a quick introduction to the subject. Those wishing to pursue the topic further couldn't do any better than the Solar Terrestrial Dispatch course offered by (Disclaimer: I have paid for and studied this course in the past and make this recommendation based solely on the material received and my own experience of the course. I have no affiliation with nor do I benefit in any way from sales of the course.)

NOAA wwv.txt reports are issued at approximately 3 hour intervals and contain the following information;

Solar Flux: A fundamental indicator of solar activity representing the amount of radio noise at 2.8GHz which correlates to the level of ionisation in the ionosphere and the F2 critical frequencies in particular. Generally speaking, the high the Solar Flux, the better the HF communications.
Kp-Index: A measure of magnetic activity. The 'p' denotes a planetary value, i.e. one that is an average of a number of observations recorded around the globe.
Ap-Index: A measure of geomagnetic activity and related to kp. Again, the 'p' denotes a planetary value, i.e. an average of a number of observations recorded around the globe.

Whereas the solar flux value follows the 11-solar cycle (that's not strictly correct, it's one of the parameters used to define the cycle) and is associated with the benign ionosphere, the Ap and Kp parameters are indicators of abrupt, usually short lived, changes of varying severity that result in a disturbed ionosphere (in terms of both plasma density and spatial distribution). Such abrupt changes typically result in depressed MUF values. As a rule of thumb, high Flux and Low Ka and Ap values lead to good HF communications, Low Flux values and high Ap and Kp values lead to poor HF communications.

Storm Warnings: The last two lines of the report contain details of storms observed or predicted over the previous and following 24 hour period. This section of the report is probably of greatest interest to the casual reader wishing to gain a quick understanding of the current state of the ionosphere. The storms are graded in level from 0-5, a '0' value indicating no storms and a '5' representing a Severe Storm, something only seen for around 4 days during a complete 11-year solar cycle. Graphical gauges are only displayed in this section if a storm warning is present. A handy pdf describing the space weather scales and the impacts associated with each level is available from NOAA

The space weather data is included within the proppy site for the benefit of users performing short term predictions and is not used by the ITURHFProp application (which powers Proppy) in any way. P.1239 defines how the values used to predict ionospheric characteristics are derived from historical datasets which have been smoothed to eliminate excursions due to unusual solar activity ITU-R P.1239-2. Smoothed input data (R12) is expected. Furthermore, the predictions provide a median value for a month, not an absolute value for a single point in time. An awareness of unusual solar activity is however useful to users performing a prediction for immediate short term use.


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