equatorial spread F

Equatorial spread F (ESF) was discovered almost a century ago using the first radio wave instrument designed to study the upper atmosphere: the ionosonde. The name came from the appearance of reflections from the normally smooth ionosphere, which were spread over the altitude frequency coordinates used by the instrument. Attempts to understand this phenomenon in any depth activated such tools as radars and in situ probes such as rockets and satellites in the 1960s. Over the next 15 years, these tools expanded our experimental understanding enormously, and new nonlinear theoretical methods developed in the late 1970s, which led to proposing a name revision from ESF to convective ionospheric storms. Interest in these phenomena continues, but a new, practical aspect has developed from the associated turbulence effects on communications (transionosphere) and navigation (GPS). The first satellite to specifically investigate this problem and the associated goal of predicting occurrences is under the umbrella of the Communications/Navigation Outage Forecast System (C/NOFS). In contemplating the successful first years of the C/NOFS program, reviewing the state of the art in our knowledge of convective ionospheric storms seems appropriate. We also present some initial results of this satellite program. A major goal of the National Space Weather Program, and of C/NOFS, is predicting these storms, analogous to thunderstorms in the lower atmosphere due to their adverse effects on communication and navigation signals. Although ambitious, predictive capability is a noble and important goal in the current technological age and is potentially within our reach during the coming decade.

“GNU Radio Beacon Receiver (GRBR) is a new digital receiver based on GNU Radio and USRP (Universal Software Radio Peripheral) [Yamamoto, 2008]. In this paper, the GRBR observations of large-scale wave structure (LSWS) and the subsequent development of equatorial spread F (ESF) using total electron content (TEC) derived from the ground based reception of signals from the radio beacon on board C/NOFS (Communications/Navigation Outage Forecasting System) satellite are presented. The other evidences of LSWS include the `satellite traces' observed in ionograms. These observations show that LSWS appears to play an important role in the development of ESF.

A Conjugate Point Equatorial Experiment (COPEX) campaign was conducted during the October–December 2002 period in Brazil, with the objective to investigate the equatorial spread F/plasma bubble irregularity (ESF) development conditions in terms of the electrodynamical state of the ionosphere along the magnetic flux tubes in which they occur. A network of instruments, including Digisondes, optical imagers, and GPS receivers, was

We performed an extensive experimental campaign (the spread F Experiment, or SpreadFEx) from September to November 2005 to attempt to define the role of neutral atmosphere dynamics, specifically wave motions propagating upward from the lower atmosphere, in seeding equatorial spread F and plasma bubbles extending to higher altitudes. Campaign measurements focused on the Brazilian sector and included ground-based optical, radar, digisonde, and GPS measurements at a number of fixed and temporary sites. Related data on convection and plasma bubble structures were also collected by GOES 12 and the GUVI instrument aboard the TIMED satellite. Initial results of our analyses of SpreadFEx and related data indicate 1) extensive gravity wave (GW) activity apparently linked to deep convection predominantly to the west of our measurement sites, 2) the presence of small-scale GW activity confined to lower altitudes, 3) larger-scale GW activity apparently penetrating to much higher altitudes sugge...

RH-560 rockets instrumented with Langmuir probes were launched from SHAR, India (dip 11 deg N) for in situ studies of electron density irregularities associated with equatorial spread-F (ESF) when the F-region plasma was drifting down and strong range spread-F was observed with an ionosonde at SHAR. A high variability was observed in the steepness of the base of the F-region. The bases were found to be steeper during the periods when the F-region plasma was drifting down. On one of the flights irregularities were observed in the region around 280 km where the gradients in electron density were downwards, indicating that the gradient drift instability is the main mechanism for their generation.

This paper presents the role of planetary waves in modulating the occurrence time of Equatorial Spread F (ESF). The investigation has been carried out using the data from the digital Ionosonde and Proton Precession Magnetometer located over Trivandrum, India (8.5° E; 77° N; 0.5° N dip lat.). The analysis shows that the start-time of the ESF during the winter months is modulated significantly by a planetary wave of quasi-16-day periodicity. It is suggested that these waves are propagated to ionospheric altitudes from lower atmosphere through modified electrodynamics since the equatorial electrojet and pre-reversal enhancement were also showed the same oscillations.

... WE Swartz. School of Electrical Engineering, Cornell University, Ithaca, New York. DT Farley. School of Electrical Engineering, Cornell University, Ithaca, New York. JW Meriwether Jr. Space Physics Research Laboratory, University of Michigan, Ann Arbor. ...

Upward transport of wave energy and momentum due to gravity, tidal and planetary waves from below and extra-tropics controls the phenomenology of the equatorial atmosphere–ionosphere system. An important aspect of this phenomenology is the development of ...

Mary Hudson is being honored as one of the 1984 James B. Macelwane award winners because her theoretical research on the microphysics of magnetospheric plasmas has been at the forefront of the field, has inspired many experimental and theoretical studies, and has stimulated her colleagues and students.From her earliest work as a graduate student, Mary has displayed a pronounced talent