Velocity of E-region HF echoes under strongly-driven electrojet conditions

Electric Field and Plasma Density Measurements in the Strongly Driven Daytime Equatorial Electrojet

Type-1 echoes from the mid-latitude E-Region ionosphere

This paper presents more data on the properties of type-1 irregularities in the nighttime midlatitude E-region ionosphere. The measurements were made with a 50-MHz Doppler radar system operating in Crete, Greece. The type-1 echoes last from several seconds to a few minutes and are characterized by narrow Doppler spectra with peaks corresponding to wave phase velocities of 250–350 m/s. The avera...

Multi-frequency observations of E-region HF radar aurora

Multi-frequency observations of E-region coherent backscatter from decametre waves reveal that auroral echoes tend to comprise two spectral components superimposed, one at low Doppler shifts, below 250 m s−1, and the other Doppler shifted to near the ion-acoustic speed or above, up to 800 m s−1. The low Doppler shift component occurs at all look directions; Doppler shifts near the ion acoustic ...

D region HF radar echoes associated with energetic particle precipitation and pulsating aurora

Milan et al. (2001) identified a class of narrow, slow-moving HF radar backscatter echoes which originate between altitudes of 80 and 100 km, the ionospheric Dand lower E-regions. These echoes appeared to be associated with the occurrence of pulsating aurora, which are known to be created by energetic electrons capable of penetrating to D region altitudes. In this study we show that these echoe...

Velocity reassignment echoes in proteins

A new echo phenomenon in proteins, a generalization of so-called temperature quench echoes, is introduced and shown to reveal, through molecular dynamics simulations, periodic motions ~normal modes! in proteins with phase coherence times of about one picosecond. The echoes are induced through reassignments of Cartesian velocities to protein atoms at times t50 and t5t ~0,t<1 ps! and appear as tw...