Angular dependence of pump-induced bottomside and topside ionospheric plasma turbulence at EISCAT

Kosch, M. J.; Mjølhus, E.; Ashrafi, M.; Rietveld, M. T.; Yeoman, T. K.; Nozawa, Satonori

doi:10.1029/2010ja016014

Cited by 7 publications

(15 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Observations of bottom and topside enhancements in the ionospheric F region were reported for the first time by Isham et al (1990). The radio window associated with the conversion from O mode to Z mode lies around the Spitze or critical angle (Ginzburg, 1970) and for a horizontally stratified ionosphere; it is of the order of 1 • , as recently reported by Kosch et al (2011) for the Tromsø F region. However, for an ionosphere containing significant electron density perturbations, the conversion to Z mode is possible also at other angles than the critical angle, Mishin et al (2001).…”

Section: Discussionsupporting

confidence: 49%

Observations of HF-induced instability in the auroral E region

et al. 2013

View full text Add to dashboard Cite

Abstract. Enhancements were observed in backscattered radar power during an ionospheric heating experiment from two distinct altitude regions in the auroral E region above Tromsø. For the experiment the EISCAT Tromsø heater was operated with O mode and X mode alternated at 4.04 MHz, close to the 3rd electron gyroharmonic. Ion-line data recorded with the EISCAT UHF radar reveal different temporal evolutions as well as different ion-line characteristics for the enhancements from the two altitude regions. The upper layer is dominated by a strong central feature, whereas the lower layer has three peaks corresponding to the central feature and the two ion lines. The altitude region of the two closely spaced (altitude separation ~ 5 km) but distinct enhancements is close to the critical altitude for the heater wave.

show abstract

Section: Discussionsupporting

confidence: 49%

Observations of HF-induced instability in the auroral E region

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Previous analyses of OZ conversion near the X = 1 condition have assumed straight isocontours of f pe , with the option of investigating how conversion depends on the angles separating the isocontour direction, the incident O-mode propagation direction, and the B 0 axis [Mjolhus, 1984;Budden, 1985;Muldrew, 1993;Nordblad and Leyser, 2010;Kosch et al, 2011;Cannon et al, 2016]. The significance of Figures 3, 6, and 7 is that radiation from an ionospheric heater can encounter a variety of isocontour directions near X = 1, necessitating a variety of conversion geometries over the latitude range where OZ conversion may occur.…”

Section: 1002/2016rs006190mentioning

confidence: 99%

“…The concept of “radio window” whereby electromagnetic radiation converts from one cold‐plasma mode to another has aroused interest in various areas of research in ionospheric radio science [ Budden , ; Mjolhus , ]. Ionospheric modification following conversion from O mode to Z mode has been of particular interest [see Muldrew , ; Nordblad and Leyser , ; Kosch et al , ; Cannon et al , , and references therein]. A nexus in plots of cold‐magnetoplasma refractive index of the O and Z propagation modes has been identified as a critical concept in the sequence of processes occurring as O‐mode radiation makes its way from powerful high frequency (HF) ground transmitters to the ionospheric F 2 layer where the Z‐mode wave packets either undergo absorption at the upper oblique resonance or suffer total reflection, depending on the F 2 layer density.…”

Section: Introductionmentioning

confidence: 99%

Sura heating facility transmissions to the CASSIOPE/e‐POP satellite

et al. 2017

View full text Add to dashboard Cite

Throughout a nighttime pass of the CASSIOPE satellite at an altitude of about 1300 km above the Sura heating facility, transmission of O‐mode radiation from Sura to the enhanced Polar Outflow Probe (e‐POP) Radio Receiver Instrument on CASSIOPE was maintained. Also, during this pass, continuous VHF/UHF transmission from the e‐POP Coherent Electromagnetic Radio Tomography radio beacon to three coordinated ground receivers in the Sura vicinity was achieved. Tomography of the VHF/UHF received wave data based on total electron content permitted the two‐dimensional distribution of ionospheric ambient electron plasma frequency fpe to be determined in the latitude‐altitude space between Sura and CASSIOPE. The foF2 values about 0.1 MHz above the Sura pump frequency of 4.3 MHz were measured by the tomography. We examine the question of whether the observations can be explained on the basis of classic propagation in a smooth ionosphere. Tracing of rays from Sura toward CASSIOPE orbital locations finds most rays reflected away from the topside by the patchy ionospheric structure in bottomside fpe. It is concluded that O‐mode ducting in underdense field‐aligned irregularities is responsible for maintaining the transionospheric transmission across the 2 min pass. O‐ to Z‐mode “radio‐window” conversion in the F region bottomside is not required to explain these data.

show abstract

“…Enhancements of the backscattered power in the ion and plasma lines of ISR measurements in the ionosphere, due to high‐power HF wave pumping, have been observed many times (e.g., Ganguly & Gordon, ; Isham et al, ; Isham, Rietveld, et al ; Isham, Hagfors, et al ; Kosch et al, ; Rietveld et al, ). Isham et al () reported ion‐line enhancements at the topside and bottomside of the F‐region observable during the first 10‐s period after heating on in magnetic zenith.…”

Section: Introductionmentioning

confidence: 99%

“…Nordblad and Leyser () also suggest that L‐mode propagation through heater induced radio windows can not be ruled out as an explanation for the Isham, Rietveld, et al () observations. In an experiment studying the angular extent of the radio window in 2004, Kosch et al () observed clear topside enhancements during a low duty cycle (3.3%), heating experiment pointed in a direction 9 ∘ south of zenith. They present observations indicating the location of the bottomside radio window to be around 7 ∘ –8 ∘ south of zenith, arguing that this can be explained by a tilt in the ionosphere, that was observed in the Dynasonde data during the experiment.…”

Section: Introductionmentioning

confidence: 99%

First Observations of Recurring HF‐Enhanced Topside Ion Line Spectra Near the Fourth Gyroharmonic

et al. 2018

View full text Add to dashboard Cite

We present first incoherent scatter radar observations of systematically recurring, high-frequency (HF)-enhanced ion line spectra at the topside F-region ionosphere, during magnetic field aligned HF pumping in an O-mode polarization. The European Incoherent Scatter UHF radar was directed in magnetic zenith on 9-11 March 2016 while stepping the pump frequency across the double resonance of the fourth harmonic of the electron gyrofrequency and the local upper hybrid frequency, in a 3-min-on, 3-min-off pump cycle. Topside and bottomside enhancements occur at the respective plasma resonance altitude and seem to be asymmetrically conditioned by the relative proximity of the pump frequency to the double resonance frequency. Further, the topside HF-induced ion line enhancements predominantly appear while the pump frequency is just below the double resonance frequency and only simultaneous to strong bottomside enhancements. A powerful, HF radio wave in O-mode, transmitted in the direction of magnetic zenith is reflected a few kilometers below the plasma resonance altitude, where the pump frequency is equal to the local plasma frequency, on the bottomside F-region in the ionosphere. Transionospheric propagation of the pump wave outside the radio window can be facilitated by density striations in the plasma, and we consider, in detail, the possible mechanisms proposed for propagation outside the standard radio window.

show abstract

Angular dependence of pump-induced bottomside and topside ionospheric plasma turbulence at EISCAT

Cited by 7 publications

References 39 publications

Observations of HF-induced instability in the auroral E region

Observations of HF-induced instability in the auroral E region

Sura heating facility transmissions to the CASSIOPE/e‐POP satellite

First Observations of Recurring HF‐Enhanced Topside Ion Line Spectra Near the Fourth Gyroharmonic

Contact Info

Product

Resources

About