Riometer-based optimization of a simple shortwave fadeout absorption model

Abstract:

Electromagnetic radiation emitted during a solar X-ray flare increases ionization in the dayside ionosphere impact high frequency radio wave propagation, a phenomenon commonly referred to as shortwave fadeout. Shortwave fadeout is an important topic of research due to its clear impacts on the high frequency radio communication user community. This paper presents improvements to current modelling techniques by constraining the data with absorption measurements from a 30 MHz relative ionospheric opacity meter (riometer) located at Ottawa, Canada (45.4° geographic latitude). Model improvements are demonstrated based on a single-event study, and for a statistical data set comprised of C, M, and X-class solar X-ray flare observed between 2006 and 2017 when the Ottawa riometer station was operational and on the dayside. Data-based optimization is shown to corrects underestimation frequently observed by other models.