Climatology of Mid-latitude Ionospheric Disturbances from the Very Large Array Low-frequency Sky Survey

Abstract

The results of a climatological study of ionospheric disturbances derived from observations of cosmic sources from the Very Large Array (VLA) Low-frequency Sky Survey (VLSS) are presented. We have used the ionospheric corrections applied to the 74 MHz interferometric data within the VLSS imaging process to obtain fluctuation spectra for the total electron content (TEC) gradient on spatial scales from a few to hundreds of kilometers and temporal scales from less than one minute to nearly an hour. The observations sample nearly all times of day and all seasons. They also span latitudes and longitudes from 28 deg. N to 40 deg. N and 95 deg. W to 114 deg. W, respectively. We have binned and averaged the fluctuation spectra according to time of day, season, and geomagnetic (Kp index) and solar (F10.7) activity. These spectra provide a detailed, multi-scale account of seasonal and intraday variations in ionospheric activity with wavelike structures detected at wavelengths between about 35 and 250 km. In some cases, trends between spectral power and Kp index and/or F10.7 are also apparent. In addition, the VLSS observations allow for measurements of the turbulent power spectrum down to periods of 40 seconds (scales of ~0.4 km at the height of the E-region). While the level of turbulent activity does not appear to have a strong dependence on either Kp index or F10.7, it does appear to be more pronounced during the winter daytime, summer nighttime, and near dusk during the spring.

accepted for publication in Radio Science

References in corpus (7)

• The VLA Low-frequency Sky Survey
• The 74MHz System on the Very Large Array
• VLSS Redux: Software Improvements applied to the Very Large Array 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
• A New Technique for Spectral Analysis of Ionospheric TEC Fluctuations Observed with the Very Large Array VHF System: From QP Echoes to MSTIDs
• Very Large Array Observations of Disturbed Ion Flow from the Plasmasphere to the Nighttime Ionosphere

Cited by in corpus (9)

• Science with the Murchison Widefield Array
• Power spectrum analysis of ionospheric fluctuations with the Murchison Widefield Array
• Density duct formation in the wake of a travelling ionospheric disturbance: Murchison Widefield Array observations
• Study of the equatorial ionosphere using the Giant Metrewave Radio Telescope (GMRT) at sub-GHz frequencies
• Exploring Earth's Ionosphere and its effect on low radio frequency observation with the uGMRT and the SKA
• Advanced spectral analysis of ionospheric waves observed with sparse arrays
• Spectral Analysis of ionospheric density variations measured with the large radio telescope in the Low-Latitude region
• 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