Relative O- and X-mode transmitted power from SuperDARN as it relates to the RRI instrument on ePOP

Gillies, R. G.; Hussey, G. C.; Sofko, G. J.; James, H. G.

doi:10.5194/angeo-28-861-2010

Cited by 13 publications

(31 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Near the end of the passes, the orientation angle ψ was varying rapidly and the ellipticity angle χ was varying between circular and linear, consistent with estimates from Gillies et al (). The ellipticity angle χ was observed to be nearly circular when the aspect angle θ was between 80° and 100° where the condition for QT propagation was more dominant near the end of the passes.…”

Section: Discussionsupporting

confidence: 87%

Polarization Characteristics Inferred From the Radio Receiver Instrument on the Enhanced Polar Outflow Probe

et al. 2018

View full text Add to dashboard Cite

The Radio Receiver Instrument (RRI) on the CAScade, Smallsat, and Ionospheric Polar Explorer/enhanced Polar Outflow Probe (CASSIOPE/e‐POP) satellite was used to receive continuous wave and binary phase shift keyed transmissions from a high‐frequency transmitter located in Ottawa, ON, Canada during April 2016 to investigate how the ionosphere affects the polarization characteristics of transionospheric high‐frequency radio waves. The spacecraft orientation was continuously slewed to maintain the dipole orientation in a plane perpendicular to the direction toward the transmitter, enabling the first in situ planar polarization determination for continuous wave and binary phase shift keyed modulated radio waves from space at times when the wave frequency is at least 1.58 times the plasma frequency. The Stokes parameters and polarization characteristics were derived from the measured data and interpreted using an existing ray tracing model. For the southern part of the passes, the power was observed to oscillate between the two dipoles of RRI, which was attributed to Faraday rotation of the radio waves. For the first time, a reversal in the rate of change of orientation angle was observed where the minimum in modeled Faraday rotation occurred. The reversal point was poleward of the point of closest approach between the satellite and transmitter; this was explained by the variations of total electron content and component of magnetic field along the direction of propagation. The received signals show both quasi‐longitudinal (QL) and quasi‐transverse characteristics. South of the transmitter the QL regime is dominant. Around the reversal point, a combination of QL and quasi‐transverse nature was observed.

show abstract

Section: Discussionsupporting

confidence: 87%

Polarization Characteristics Inferred From the Radio Receiver Instrument on the Enhanced Polar Outflow Probe

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Depending on propagation direction and frequency, the two modes may have quite different amplitudes. Although not presented explicitly in this study, the distribution of power between the O and X modes and the effect of this distribution on the polarization results has been calculated based on equations derived by Gillies et al [2010b].…”

Section: Hf Propagation Modelingmentioning

confidence: 99%

“…These studies compared features observed at the ISIS II satellite to the same parameters determined using computational models. Finally, the expected distribution of power between the two modes of propagation, which will be detectable by the RRI, was calculated for various horizontally stratified ionospheric profiles by Gillies et al [2010b]. The current analysis deals with calculations of radio wave raypaths using two‐dimensional electron density profiles to model the effects of ionospheric enhancements and depletions on the polarization state of the signal received at the RRI.…”

Section: Introductionmentioning

confidence: 99%

Modeling measurements of ionospheric density structures using the polarization of high‐frequency waves detected by the Radio Receiver Instrument on the enhanced Polar Outflow Probe

et al. 2012

Self Cite

View full text Add to dashboard Cite

The Cascade SmallSat and Ionospheric Polar Explorer (CASSIOPE) satellite is to be launched in late 2012. On board this satellite will be a suite of eight scientific instruments composing the enhanced Polar Outflow Probe (ePOP). The Radio Receiver Instrument (RRI) on ePOP will be used to receive high‐frequency (HF) (10–18 MHz) transmissions from ground transmitters such as the Super Dual Auroral Radar Network (SuperDARN) array. Modeling of the characteristics of the HF signal received at ePOP for various ionospheric conditions has been undertaken in preparation for this RRI‐SuperDARN experiment. The effect of ionospheric electron density enhancements and depletions on signal parameters such as polarization and mode delay difference has been modeled. It has been found that at HF the polarization state of the received signal is highly sensitive to regions of locally enhanced or depleted electron density in the ionosphere. In particular, analysis of the orientation angle of the received signal, which changes because of Faraday rotation as the spacecraft passes over a ground transmitter, will allow detection of small‐scale electron density structures (on the order of tens of kilometers) with electron densities as little as 10% different from background values. Because of the sensitivity of the polarization of HF transionospheric waves, the signatures of these small‐scale and relatively weak ionospheric density structures will be apparent. Larger and denser structures will also be detectable from both the polarization state and other signal parameters, such as signal delay. The modeling demonstrates that detailed analysis of the signal parameters received at the ePOP satellite will allow determination of the location, size, and density of structures in the ionosphere.

show abstract

“…Inspection of equation (2) Gillies et al [2010b] predicted that it is the X-mode which primarily participates in SuperDARN scatter).…”

Section: Scattering Volume Plasma Frequency From Frequency Shiftsmentioning

confidence: 99%

Improvement of HF coherent radar line-of-sight velocities by estimating the refractive index in the scattering volume using radar frequency shifting

et al. 2011

Self Cite

View full text Add to dashboard Cite

[1] Measurements of ionospheric drift velocities using HF coherent scatter radars, such as SuperDARN, are generally underestimated because the refractive index in the scattering volume has not been taken into account. Refractive index values evaluated from electron density measurements, international reference ionosphere predictions, or elevation angle measurements have been applied to SuperDARN velocities in past studies. However, the SuperDARN velocities so obtained were, on average, statistically lower than velocities measured by other instruments. One possible explanation for this underestimation is that HF coherent scatter preferentially occurs in regions of the ionosphere where the scattering cross section is largest, and such regions are characterized by small-scale structures which have higher-than-average electron densities. This was not accounted for in past studies because the refractive index estimates used were from large scale and therefore smoothed estimates of electron density. In this paper, a new method of estimating the actual electron density (or plasma frequency) at the location of SuperDARN scatter (instead of the larger-scale background electron density) is presented. This method takes advantage of the frequency shifts which occur in normal SuperDARN operations. If it is assumed that, on average, the actual ionospheric drift velocity and plasma frequency are roughly constant before and after a shift in frequency, any change in measured velocity as SuperDARN changes frequency is due to a change in refractive index. An analysis of the change in the measured velocity resulting from each shift in frequency gives an experimentally based estimate of the electron density in the scattering volume. A statistical analysis of essentially all frequency shifts by SuperDARN and the estimated electron densities in the scattering volume has been performed. The resulting electron densities are appreciably higher than previous methods to estimate electron density predict. Application of this new method to velocity comparisons between SuperDARN and other instruments results in agreement between the HF radar and non-HF radar velocities for the first time. This new method allows for the first direct measurements of electron densities in the exact locations where the cross section for SuperDARN scatter maximizes.

show abstract

Relative O- and X-mode transmitted power from SuperDARN as it relates to the RRI instrument on ePOP

Cited by 13 publications

References 17 publications

Polarization Characteristics Inferred From the Radio Receiver Instrument on the Enhanced Polar Outflow Probe

Polarization Characteristics Inferred From the Radio Receiver Instrument on the Enhanced Polar Outflow Probe

Modeling measurements of ionospheric density structures using the polarization of high‐frequency waves detected by the Radio Receiver Instrument on the enhanced Polar Outflow Probe

Improvement of HF coherent radar line-of-sight velocities by estimating the refractive index in the scattering volume using radar frequency shifting

Contact Info

Product

Resources

About