A New Technique for Spectral Analysis of Ionospheric TEC Fluctuations Observed with the Very Large Array VHF System: From QP Echoes to MSTIDs

Abstract

We have used a relatively long, contiguous VHF observation of a bright cosmic radio source (Cygnus A) with the Very Large Array (VLA) through the nighttime, midlatitude ionosphere to demonstrate the phenomena observable with this instrument. In a companion paper, we showed that the VLA can detect fluctuations in total electron content (TEC) with amplitudes of <0.001 TECU and can measure TEC gradients with a precision of about 0.0002 TECU/km. We detail two complementary techniques for producing spectral analysis of these TEC gradient measurements. The first is able to track individual waves with wavelengths of about half the size of the array (~20 km) or more. This technique was successful in detecting and characterizing many medium-scale traveling ionospheric disturbances (MSTIDs) seen intermittently throughout the night and has been partially validated using concurrent GPS measurements. Smaller waves are also seen with this technique at nearly all times, many of which move in similar directions as the detected MSTIDs. The second technique allows for the detection and statistical description of the properties of groups of waves moving in similar directions with wavelengths as small as 5 km. Combining the results of both spectral techniques, we found a class of intermediate and small scale waves which are likely the quasi-periodic (QP) echoes that have been observed to occur within sporadic-E (Es) layers. We find two distinct populations of these waves. The members of one population are coincident in time with MSTIDs and are consistent with being generated within Es layers by the E-F coupling instability. The other population seems more influenced by the neutral wind, similar to the predominant types of QP echoes found by the Sporadic-E Experiments over Kyushu (Fukao et al. 1998; Yamamoto et al. 2005).

Accepted for publication in Radio Science

References in corpus (3)

• The VLA Low-frequency Sky Survey
• Probing Fine-Scale Ionospheric Structure with the Very Large Array Radio Telescope
• High-precision Measurements of Ionospheric TEC Gradients with the Very Large Array VHF System

Cited by in corpus (14)

• Probing Ionospheric Structures using the LOFAR radio telescope
• Power spectrum analysis of ionospheric fluctuations with the Murchison Widefield Array
• High-precision Measurements of Ionospheric TEC Gradients with the Very Large Array VHF System
• Very Large Array Observations of Disturbed Ion Flow from the Plasmasphere to the Nighttime Ionosphere
• Climatology of Mid-latitude Ionospheric Disturbances from the Very Large Array Low-frequency Sky Survey
• Density duct formation in the wake of a travelling ionospheric disturbance: Murchison Widefield Array observations
• Insights into the nature of northwest-to-southeast aligned ionospheric wavefronts from contemporaneous Very Large Array and ionosondes observations
• Study of the equatorial ionosphere using the Giant Metrewave Radio Telescope (GMRT) at sub-GHz frequencies
• Spectral Analysis of ionospheric density variations measured with the large radio telescope in the Low-Latitude region
• Advanced spectral analysis of ionospheric waves observed with sparse arrays
• Ionospheric observations of Underground Nuclear Explosions (UNE) using GPS and the Very Large Array
• Probing the ionosphere by the pulsar B0950+08 with help of RadioAstron ground-space baselines
• A new angle for probing field-aligned irregularities with the Murchison Widefield Array
• Probing Equatorial Ionospheric TEC at Sub-GHz Frequencies with Wide-Band (B4) uGMRT Interferometric Data