On the diurnal variation of the E-region coherent HF echo occurrence

Carter, Brett; Makarevich, R. A.

doi:10.1016/j.jastp.2010.02.004

Cited by 6 publications

(10 citation statements)

References 42 publications

(72 reference statements)

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“…These features are fully consistent with previous studies of auroral E region echoes, particularly those that utilized multiple radars in different MLT sectors [ Makarevich , ; Carter and Makarevich , ]. However, these previous studies did not consider how a spatial pattern gradually changes from one MLT sector to another.…”

Section: Diurnal Variations Of E Region Echo Occurrence and Populationssupporting

confidence: 89%

Electric field control of E region coherent echoes: Evidence from radar observations at the South Pole

2015

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Characteristics and formation mechanisms of E region plasma irregularities at high latitudes are investigated using observations with the newly deployed Super Dual Auroral Radar Network (SuperDARN) radar at the South Pole Antarctic station (SPS) near a magnetic latitude (MLAT) of 75°S. It is shown that E region echo occurrence at SPS exhibits a diurnal variation that is significantly different from those at auroral and polar cap latitudes. Moreover, analysis of major spectral populations also showed a distinct and previously unreported diurnal pattern. The plasma drift velocity estimates are derived at E region ranges of SPS, leveraging the SPS radar's position well within the MLAT region where SuperDARN convection estimates are well constrained by the data. It is shown that E region irregularity occurrence increases when the convection direction is within the SPS field of view and/or when the plasma drift component is comparable with the nominal ion‐acoustic speed Cs of 350 m/s. This is the expected behavior for irregularities generated directly by the modified two‐stream plasma instability (MTSI). On the other hand, irregularity velocity dependence on convection velocity showed an unexpected saturation at velocity values smaller than nominal Cs. It is demonstrated that the convection velocity at which irregularity velocity starts to differ from the convection component and to approach a maximum value is dependent on the magnetic aspect angle. Moreover, the maximum velocity value itself also depends on the aspect angle. The observed behavior is discussed in context of recent models that involve evolving aspect angles as a key characteristic of MTSI saturation.

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Section: Diurnal Variations Of E Region Echo Occurrence and Populationssupporting

confidence: 89%

Electric field control of E region coherent echoes: Evidence from radar observations at the South Pole

2015

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“…The difference in backscatter properties is almost certainly due to the appearance of auroral irregularities within the designated range interval as the oval expands. Carter and Makarevich (2010) extended the study of E region backscatter to cover a total of 15 radars over the same 3-year period. As the bulk of the radars operate at high latitudes, the contrasts with TIG were illuminating.…”

Section: Auroral Irregularitiesmentioning

confidence: 99%

Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars

Watanabe

Ruohoniemi

Lester

et al. 2019

Prog Earth Planet Sci

172

166

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The Super Dual Auroral Radar Network (SuperDARN) is a network of high-frequency (HF) radars located in the high-and mid-latitude regions of both hemispheres that is operated under international cooperation. The network was originally designed for monitoring the dynamics of the ionosphere and upper atmosphere in the high-latitude regions. However, over the last approximately 15 years, SuperDARN has expanded into the mid-latitude regions. With radar coverage that now extends continuously from auroral to sub-auroral and mid-latitudes, a wide variety of new scientific findings have been obtained. In this paper, the background of mid-latitude SuperDARN is presented at first. Then, the accomplishments made with mid-latitude SuperDARN radars are reviewed in five specified scientific and technical areas: convection, ionospheric irregularities, HF propagation analysis, ion-neutral interactions, and magnetohydrodynamic (MHD) waves. Finally, the present status of mid-latitude SuperDARN is updated and directions for future research are discussed.

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“…However, both Figures and show an increase in backscatter occurrence at close range. During less disturbed conditions, close range returns are often attributed to E region scatter [ Makarevitch et al , ; Makarevich et al , ; Carter and Makarevich , ]. Ray tracing suggests that the close range backscatter during more disturbed storm conditions also originates from the E region.…”

Section: Discussionmentioning

confidence: 99%

SuperDARN backscatter during intense geomagnetic storms

et al. 2016

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It is often stated that high‐frequency radars experience a loss of backscatter during geomagnetic storm events. The occurrence of backscatter during 25 intense geomagnetic storms was examined using data from the Bruny Island and Kodiak radars and a superposed epoch analysis. It was found that while a reduction of backscatter occurred in the middle to far ranges, there was an increase in the amount of backscatter from close range following storm onset. Ray tracing showed that an enhanced charge density in the E region can reduce the chance of F region and increase the chance of E region backscatter. It was also shown that reduction in backscatter cannot be explained by D region absorption. Using a normalized SYM‐H value, percentage time through recovery phase can be estimated during storm progression which allows a prediction of backscatter return in real time that accounts for varying storm recovery phase duration.

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On the diurnal variation of the E-region coherent HF echo occurrence

Cited by 6 publications

References 42 publications

Electric field control of E region coherent echoes: Evidence from radar observations at the South Pole

Electric field control of E region coherent echoes: Evidence from radar observations at the South Pole

Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars

SuperDARN backscatter during intense geomagnetic storms

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