Assessing the contamination of SuperDARN global convection maps by non-F-region backscatter

Chisham, G.; Pinnock, M.

doi:10.5194/angeo-20-13-2002

Cited by 41 publications

(47 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It clarifies the latitudinal extent of the high-speed flow around 70 • MLAT. While the total cross-cap potential remains virtually unchanged, the new procedure results in substantially higher local fitted velocities and a noticeable change in the configuration of equipotential lines at the mesoscale level, in agreement with Chisham and Pinnock (2002).…”

Section: Fitting Experimental Datasupporting

confidence: 72%

“…Application of the conventional FITACF procedures in this case leads to incorrect estimates of V , W and other parameters producing large fitting errors. Chisham and Pinnock (2002) showed that contamination from SS can considerably alter mesoscale features of the fitted convection pattern and developed a technique for eliminating SS and MS from range-velocity distribution of echoes based on empirical identification of HF propagation modes. A similar approach was applied by Ponomarenko et al (2007), who successfully removed most MS from the data by applying the Blanchard-Baker algorithm with extended empirical thresholds for W and |V |.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of mixed scatter on SuperDARN convection maps

2008

View full text Add to dashboard Cite

Abstract. The SuperDARN radars map high-latitude ionospheric plasma drift velocities by measuring the Doppler frequency shift of HF signals scattered by decameter electron density irregularities. In many cases the ionospheric returns are contaminated by strong scatter from the ground or sea surface. In this paper we develop and test a two-component fitting algorithm to separate ionospheric and surface scatter components. Application of the technique to sample data reveals that mixed scatter may considerably distort ionospheric convection patterns derived from the radar data and can cause underestimation of the plasma drift velocity.

show abstract

Section: Fitting Experimental Datasupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Effects of mixed scatter on SuperDARN convection maps

2008

View full text Add to dashboard Cite

show abstract

“…However, it is inevitable that some ground scatter has been included in this survey. A more complete removal of ground scatter from the data set could be achieved [Chisham and Pinnock, 2002] by increasing the limits set for the identification of ground scatter from those used; however this would also lead to the unwanted removal of real ionospheric scatter. This would lead to fewer time series available for use (in fact considerably so) with a consequent increase in spectral uncertainty.…”

Section: Methodsmentioning

confidence: 99%

A statistical analysis of ionospheric velocity and magnetic field power spectra at the time of pulsed ionospheric flows

Abel

Freeman

2002

J. Geophys. Res.

View full text Add to dashboard Cite

[1] We analyze the power spectrum of the line-of-sight ionospheric velocity measured by the SuperDARN CUTLASS Finland radar and of contemporaneous magnetic field perturbations measured by nearby IMAGE magnetometers. The measurements come from 69-87°AACGM latitude and 0415-2230 MLT during 58 intervals of pulsed ionospheric flow between March 1995 and September 1996. The median power spectrum of both the velocity and magnetic field is of power law form with a best fit exponent of À0.5 and À1.3, respectively. By simulating the effect of the finite sample window on the measured spectral exponent and on the structure seen in the power spectral density of individual spectra, we show that the measured spectral exponent actually corresponds to a true exponent of À0.95 for the velocity and À1.8 for the magnetic field. Furthermore, it is shown that the difference in the exponents of the velocity and magnetic field spectra is at least in part due to a spatial smoothing effect that causes the spectral exponent of the ground magnetic spectrum to be less than that of the ionospheric current spectrum producing it. The power law power spectrum implies that there is no preferred timescale for ionospheric velocity and current fluctuations in the observed frequency range. It is proposed that this scale-free nature may arise from the intermittent, turbulent nature of the interplanetary magnetic field causing magnetic reconnection to occur at the magnetopause on a wide range of spatial and temporal scales.

show abstract

“…occasion, E region backscatter may also contaminate F region data sets which can lead to much smaller Doppler velocities observed by SuperDARN (Chisham and Pinnock, 2002;Makarevich, 2008Makarevich, , 2010Bahcivan et al, 2013).…”

Section: R a Makarevich And W A Bristow: Superdarn And Pfisr F Rementioning

confidence: 99%

“…In large part because of this expectation, various restrictions are often employed in CSR/ISR and CSR/LEO comparative studies such as velocity filtering and selection of uniform-flow events (e.g., Davies et al, 1999;Drayton et al, 2005;Gillies et al, 2009). The other related aspect is possible effects of ground and E region scatter, both of which can effectively suppress HF radar velocity significantly below the convection component (Davies et al, 1999;Chisham and Pinnock, 2002;Makarevitch et al, 2004). While standard criteria on coherent echo velocity, width, and range eliminate most of ground and E region echoes, additional restrictions have been shown to improve correlations with ISR measurements even further, from ∼ 0.7 linear correlations to ∼ 0.9 (Gillies et al, 2009).…”

Section: Irregularity and Convection Velocitiesmentioning

confidence: 99%

Coordinated radar observations of plasma wave characteristics in the auroral F region

Makarevich

Bristow

2014

Ann. Geophys.

View full text Add to dashboard Cite

Abstract. Properties of decameter-scale plasma waves in the auroral F region are investigated using coordinated observations of plasma wave characteristics with the Kodiak HF coherent radar (KOD) and Poker Flat Incoherent Scatter Radar (PFISR) systems in the Alaskan sector. We analyze one event on 14 November 2012 that occurred during the first PFISR Ion-Neutral Observations in the Thermosphere (PINOT) campaign when exceptionally good F region backscatter data at 1 s resolution were collected by KOD over the wide range of locations also monitored by PFISR. In particular, both radar systems were observing continuously along the same magnetic meridian, which allowed for a detailed comparison between the line-of-sight (l-o-s) velocity data sets. It is shown that l-o-s velocity correlation for data points strictly matched in time (within 1 s) depends strongly on the number of ionospheric echoes detected by KOD in a given post-integration interval or, equivalently, on the KOD echo occurrence in that interval. The l-o-s velocity correlations reach 0.7-0.9 for echo occurrences exceeding 70 %, while also showing considerable correlations of 0.5-0.6 for occurrences as low as 10 %. Using the same approach of strictly matching the KOD and PFISR data points, factors controlling coherent echo power are investigated, focusing on the electric field and electron density dependencies. It is demonstrated that the signal-to-noise ratio (SNR) of F region echoes increases nearly monotonically with an increasing electric field strength as well as with an increasing electron density, except at large density values, where SNR drops significantly. The electric field control can be understood in terms of the growth rate of the gradient-drift waves being proportional to the convection drift speed under conditions of fast-changing convection flows, while the density effect may involve over-refraction at large density values and radar backscatter power proportionality to the perturbation density.

show abstract

Assessing the contamination of SuperDARN global convection maps by non-F-region backscatter

Cited by 41 publications

References 37 publications

Effects of mixed scatter on SuperDARN convection maps

Effects of mixed scatter on SuperDARN convection maps

A statistical analysis of ionospheric velocity and magnetic field power spectra at the time of pulsed ionospheric flows

Coordinated radar observations of plasma wave characteristics in the auroral F region

Contact Info

Product

Resources

About