High‐Resolution Observation of Heater‐Induced Daytime Plasma Fluctuations at Arecibo

Abstract

Numerous experiments have observed the formation of field-aligned irregularities (FAI) during ionospheric heating by high frequency (HF) waves (Carlson & Duncan, 1977;Duncan & Behnke, 1978;Gordon & Carlson, 1974;Utlaut & Violette, 1974). For spatial scales (perpendicular to the field lines) on the order of several kilometers, the formation of these irregularities is frequently attributed to a combination of several plasma instabilities near the altitude where the ordinary mode of the HF heater wave is reflected (Gondarenko et al., 2005). In particular, the resonance instability gives rise to the formation of striations in the plasma on smaller scales (several meters) aligned to the geomagnetic field corresponding to strongly localized enhancements of the electron temperature and depletions of several percent in the electron density (Gurevich et al., 1995(Gurevich et al., , 1998. These irregularities then give rise to additional non-linear effects such as bunching of striations on the kilometer-scale due to self-focusing effects, Langmuir turbulence, etc.

Science goals for a high-frequency radar and radio imaging array

“…To obtain the true directions, HF wave propagation must be taken into account. HF propagation codes, also known as ray tracing codes, along with observations and models of the profile and structure of the ionosphere, may be used as needed to correct images and arrival angles for distortions caused by the ionosphere (Henderson et al, 2022). Density profile information for ray tracing calculations may be obtained from the instrument cluster operating on Culebra Island, Puerto Rico (PI Dr. Pedrina Terra), from the Digisonde and VIPIR HF radars operating in Cayey, Puerto Rico (PI Dr. Terence Direction angles of artificially-stimulated "downshifted peak" (DP) radio emissions computed from raw voltage interferometer data taken on 6 October 2004 near Tromsø, Norway (Tereshchenko et al, 2006).…”