High‐Frequency Communications Response to Solar Activity in September 2017 as Observed by Amateur Radio Networks
by Nathaniel A. Frissell

2019-05-07 287 views

Long before satellite communications, high frequency (HF, 3–30 MHz) radio was the primary method for long distance, over-the-horizon wireless communications. HF signals are able to travel long distances by refracting off of the ionosphere in what is known as “skip” or “skywave” propagation. Aside from a transmitter and receiver, no additional technological infrastructure is needed. Because of this, even in the modern age of space‐borne relays and widely distributed Internet availability, […]

Statistical Analysis of Solar Events Associated with storm sudden commencements in the magnetosphere
by K. Bocchialini et al.*

2018-07-10 432 views

We developed an innovative approach by studying each Earth-directed event leading to a storm sudden commencement (SSC) in the magnetosphere during 2002 (maximum activity of Cycle 23). This unprecedented, comprehensive study consists of: i) starting from the list of 32 SSCs listed by the International Service of Geomagnetic Indices (ISGI) of the Observatory de l’Ebre, ii) linking each SSC to a CME, iii) filling in the observational gaps along the […]

The 30 cm solar radio flux: a new proxy for upper atmosphere specification
by Thierry Dudok de Wit and Sean Bruinsma

2017-06-27 1,271 views

The 10.7 cm solar radio flux is a widely (if not the most widely) used proxy for solar activity. However, other centimetric wavelengths have also been monitored, some routinely and for several decades. Such observations provide unique records of long-term solar variability. We find that the radio flux at 30 cm receives relatively stronger contributions from Bremsstrahlung vs gyro-resonance emissions (as compared to the 10.7 cm flux); as a consequence, […]

Microwave emission as a proxy of CME speed in ICME forecasting
by Carolina Salas Matamoros, Ludwig Klein and Gerard Trottet

2017-05-09 680 views

Coronal Mass Ejections (CMEs) are one type of interplanetary structure that mostly affect the geomagnetic field (e.g. Gonzalez and Tsurutani, 1987; Zhang et al, 2007). These structures are observed and studied through coronagraphic images. The basic limitation of the coronagraph is that it shows the corona only in the plane of the sky, and blocks by necessity the view on the solar disk. Thus, the projection effect in the kinematic […]